Conservapedia - User contributions [en]

Global warming

2008-10-22T22:43:59Z

ReaganFan0101:

{{featured article}}
{{pp-semi-vandalism|small=yes}}
{{dablink|This article is about the current period of increasing global temperature. For other periods of warming in Earth's history, see [[Paleoclimatology]] and [[Geologic temperature record]].}}



{{Double image stack|right|Instrumental Temperature Record.png|Global Warming Map.jpg|280|Global mean surface temperature anomaly relative to 1961–1990|Mean surface temperature anomalies during the period 1995 to 2004 with respect to the average temperatures from 1940 to 1980}}

'''Global warming''' is the increase in the [[Instrumental temperature record|average measured temperature]] of the [[Earth]]'s near-surface air and [[ocean]]s since the mid-20th century, and its projected continuation.

Global surface temperature increased 0.74 [[Plus-minus sign|±]] 0.18 °[[Celsius|C]] (1.33 ± 0.32 °[[Fahrenheit|F]]) during the 100 years ending in 2005.<ref name="grida7a">{{cite web | url= http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf | format=[[Portable Document Format|PDF]] | title=Summary for Policymakers | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2007-02-02 | date=[[2007-02-05]] | publisher=[[Intergovernmental Panel on Climate Change]]|quote=The updated hundred-year linear trend (1906 to 2005) of 0.74 °C [0.56 °C to 0.92 °C] is therefore larger than the corresponding trend for 1901 to 2000 given in the TAR of 0.6 °C [0.4 °C to 0.8 °C].}}</ref><ref>Global surface temperature is defined in the [[AR4|IPCC Fourth Assessment Report]] as the average of near-surface air temperature over land and sea surface temperature.</ref> The [[Intergovernmental Panel on Climate Change]] (IPCC) concludes "most of the observed increase in globally averaged temperatures since the mid-twentieth century is very likely [[Attribution of recent climate change|due to]] the observed increase in [[anthropogenic]] [[greenhouse gas]] concentrations"<ref name="grida7">{{cite web | url= http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf | format=[[Portable Document Format|PDF]] | title=Summary for Policymakers | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2007-02-02 | date=[[2007-02-05]] | publisher=[[Intergovernmental Panel on Climate Change]]|quote=}}</ref><ref>Global surface temperature is defined in the [[AR4|IPCC Fourth Assessment Report]] as the average of near-surface air temperature over land and sea surface temperature.</ref> via an enhanced [[greenhouse effect]]. Natural phenomena such as [[solar variation]] combined with [[volcano]]es probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward.<ref>
{{cite web | url= http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch09.pdf | format=[[Portable Document Format|PDF]] | title=Understanding and Attributing Climate Change | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2007-05-20 | date=[[2007-05-07]] | publisher=[[Intergovernmental Panel on Climate Change]] | last=Hegerl | first=Gabriele C. | coauthors=''et al.'' | pages=690 | quote=Recent estimates (Figure 9.9) indicate a relatively small combined effect of natural forcings on the global mean temperature evolution of the seconds half of the twentieth century, with a small net cooling from the combined effects of solar and volcanic forcings}}</ref><ref>{{cite journal | last=Ammann | first = Caspar | coauthors =''et al.'' | date=[[2007-04-06]] | title=Solar influence on climate during the past millennium: Results from ransient simulations with the NCAR Climate Simulation Model | journal=Proceedings of the National Academy of Sciences of the United States of America | volume=104 | issue=10 | pages=3713–3718 | url=http://www.pnas.org/cgi/reprint/104/10/3713.pdf | format=[[Portable Document Format|PDF]] | quote=However, because of a lack of interactive [[ozone]], the model cannot fully simulate features discussed in (44)." "While the NH temperatures of the high-scaled experiment are often colder than the lower bound from proxy data, the modeled decadal-scale NH surface temperature for the medium-scaled case falls within the uncertainty range of the available temperature reconstructions. The medium-scaled simulation also broadly reproduces the main features seen in the proxy records." "Without anthropogenic forcing, the 20th century warming is small. The simulations with only natural forcing components included yield an early 20th century peak warming of ≈0.2 °C (≈1950 AD), which is reduced to about half by the end of the century because of increased volcanism. | doi=10.1073/pnas.0605064103 | pmid=17360418}}</ref> These basic conclusions have been endorsed by at least 30 [[Scientific opinion on climate change|scientific societies and academies of science]],<ref>The 2001 joint statement was signed by the scientific academies of [[Australia]], [[Belgium]], [[Brazil]], [[Canada]], [[the Caribbean]], [[China]], [[France]], [[Germany]], [[India]], [[Indonesia]], [[Ireland]], [[Italy]], [[Malaysia]], [[New Zealand]], [[Sweden]], and the [[UK]]. The 2005 statement added [[Japan]], [[Russia]], and the [[U.S.]] The 2007 statement added [[Mexico]] and [[South Africa]]. Professional societies include American Meteorological Society, American Geophysical Union, American Institute of Physics, American Astronomical Society, American Association for the Advancement of Science, Stratigraphy Commission of the Geological Society of London, Geological Society of America, American Chemical Society, and Engineers Australia.</ref> including all of the national academies of science of the [[G8|major industrialized countries]].<ref>{{cite web | title = The Science Of Climate Change | publisher = [[Royal Society]] | url = http://royalsociety.org/displaypagedoc.asp?id=13619 | accessdate = 2008-01-04 |month=May | year=2001}}</ref><ref>{{cite web | title = Joint science academies' statement: Global response to climate change | publisher = [[Royal Society]] | url = http://royalsociety.org/displaypagedoc.asp?id=20742 | accessdate = 2008-01-04 |month=June | year=2005}}</ref><ref>{{cite web | title = Joint science academies' statement on growth and responsibility: sustainability, energy efficiency and climate protection | publisher = [http://www.pik-potsdam.de/index_html Potsdam Institute for Climate Impact Research] | url = http://www.pik-potsdam.de/aktuelles/archiv/aktuelle/dateien/G8_Academies%20Declaration.pdf | accessdate = 2008-01-04 |month=May | year=2007|format=PDF}}</ref> While [[List of scientists opposing the mainstream scientific assessment of global warming|individual scientists]] have voiced disagreement with these findings,<ref>
{{cite web | title = Don't fight, adapt | publisher = [[National Post]] | url = http://www.nationalpost.com/news/story.html?id=164002 | accessdate = 2007-11-18 |month=December | year=2007}}
</ref> the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions.<ref>{{cite web | title = A guide to facts and fictions about climate change | publisher = [[Royal Society]] | url = http://www.royalsoc.ac.uk/downloaddoc.asp?id=1630 | accessdate = 2007-11-18 | month = March | year = 2005 | quote = "However, the overwhelming majority of scientists who work on climate change agree on the main points"}}</ref><ref>{{cite web | title = Beyond the Ivory Tower: The Scientific Consensus on Climate Change | publisher = [[Science Magazine]] | url = http://www.sciencemag.org/cgi/content/full/306/5702/1686 | accessdate = 2008-01-04 |month=December | year=2004}}</ref>

[[Climate model]] projections summarized by the IPCC indicate that average global surface temperature will likely rise a further {{nowrap|1.1 to 6.4 °C}} {{nowrap|(2.0 to 11.5 °F)}} during the twenty-first century.<ref name="grida7" /> This range of values results from the use of differing [[Special Report on Emissions Scenarios|scenarios]] of future [[greenhouse gas]] emissions as well as models with differing [[climate sensitivity]]. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a thousand years even if greenhouse gas levels are stabilized. The delay in reaching equilibrium is a result of the large heat capacity of the oceans.<ref name="grida7" />

Increasing global temperature is expected to cause [[sea level rise|sea levels to rise]], an increase in the intensity of [[extreme weather]] events, and significant changes to the amount and pattern of [[precipitation (meteorology)|precipitation]], likely leading to an expanse of tropical areas and increased pace of [[desertification]]. Other expected [[effects of global warming]] include changes in [[agricultural yield]]s, modifications of trade routes, [[retreat of glaciers since 1850|glacier retreat]], mass species [[extinction risk from climate change|extinctions]] and increases in the ranges of [[Vector (biology)|disease vectors]].

Remaining scientific [[uncertainty|uncertainties]] include the amount of warming expected in the future, and how warming and related changes will vary from region to region around the globe. [[List of Kyoto Protocol signatories|Most national governments]] have signed and ratified the [[Kyoto Protocol]] aimed at reducing greenhouse gas emissions, but there is ongoing [[Politics of global warming|political]] and [[global warming controversy|public debate]] worldwide regarding what, if any, action should be taken to [[Mitigation of global warming|reduce or reverse]] future warming or to [[Adaptation to global warming|adapt]] to its expected consequences.

==Greenhouse effect==
{{main|Greenhouse gas|Greenhouse effect}}

The detailed [[attribution of recent climate change|causes of the recent warming]] remain an active field of research, but the [[scientific opinion on climate change|scientific consensus]]<ref>
{{cite web |title=Joint science academies' statement: The science of climate change | url=http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13619 | format=[[Active Server Pages|ASP]] | quote=The work of the Intergovernmental Panel on Climate Change (IPCC) represents the consensus of the international scientific community on climate change science| publisher = [[Royal Society]] | date =[[2001-05-17]] |accessdate=2007-04-01}}
</ref><ref>{{cite journal | date=[[2007-10-18]] | title=Rising to the climate challenge | journal=[[Nature (journal)|Nature]] | volume=449 | issue=7164 | url=http://www.nature.com/nature/journal/v449/n7164/full/449755a.html | accessdate=2007-11-06 | pages=755 | doi=10.1038/449755a}}</ref>
is that the increase in atmospheric greenhouse gases due to human activity caused most of the warming observed since the start of the [[Industrial Revolution|industrial era]]. This attribution is clearest for the most recent 50 years, for which the most detailed data are available.

The greenhouse effect was theorized by [[Joseph Fourier]] in 1824<ref>Cowie, J. (2007). ''Climate Change: Biological and Human Aspects''. Cambridge University Press. ISBN 978-0521696197. p. 3</ref><ref>{{cite web | title=The Discovery of Global Warming | url=http://www.aip.org/history/climate/co2.htm | format=[[HTML]] | accessdate=2008-10-14 | year=2008 | publisher=[[AIP]]}}</ref><ref>{{cite journal | first=Jean-Baptiste Joseph | last=Fourier | year=1827 | title=M´emoire sur les Temp´eratures du Globe Terrestre et des Espaces Plan´etaires | journal=M´emoires d l’Acad´emie Royale des Sciences de l’Institute de France | volume=VII | url=http://geosci.uchicago.edu/~rtp1/papers/Fourier1827Trans.pdf | accessdate=2008-10-16 | pages=570-604 }} Translated by R. T. Pierrehumbert</ref> and was first investigated quantitatively by [[Svante Arrhenius]] in 1896. It is the process by which [[Absorption (electromagnetic radiation)|absorption]] and emission of [[infrared]] radiation by [[Atmosphere|atmospheric gases]] warm a [[planet]]'s lower atmosphere and surface.

[[Image:Mauna Loa Carbon Dioxide-en.svg|thumb|280px|right|Recent increases in atmospheric carbon dioxide (CO2). The monthly CO2 measurements display small seasonal oscillations in an overall yearly uptrend; each year's maximum is reached during the [[Northern Hemisphere]]'s late spring, and declines during the Northern Hemisphere growing season as plants remove some CO2 from the atmosphere.]]

Existence of the greenhouse effect as such is not disputed. Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F), without which Earth would be uninhabitable.<ref name="IPCC_WG1_AR4_Ch1">{{cite web | title=IPCC WG1 AR4 Report — Chapter 1: Historical Overview of Climate Change Science | url=http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch01.pdf | format=[[Portable Document Format|PDF]] | accessdate=2007-10-07 | year=2007 | publisher=[[IPCC]]| quote=To emit 240 W m–2, a surface would have to have a temperature
of around –19 °C. This is much colder than the conditions
that actually exist at the Earth’s surface (the global mean surface
temperature is about 14 °C). Instead, the necessary –19 °C is found
at an altitude about 5 km above the surface.
| pages = p97 (pdf page 5 of 36)
| work=IPCC WG1 AR4 Report
}}</ref><ref>Note that the Greenhouse Effect produces a temperature increase of about
33 °C (59 °F) with respect to black body predictions and not a surface temperature of 33 °C (91 °F) which is {{convert|32|°F|°C|abbr=on}} higher. The average surface temperature is about 14 °C (57 °F).
Also note that both the
Celsius and Fahrenheit temperatures are expressed to 2 significant figures even though the conversion formula produces 3.
</ref> On Earth, the major greenhouse gases are [[water vapor]], which causes about 36–70 percent of the greenhouse effect ([[Cloud forcing|not including clouds]]); [[carbon dioxide]] (CO2), which causes 9–26 percent; [[methane]] (CH4), which causes 4–9 percent; and [[ozone]], which causes 3–7 percent.<ref>{{cite journal| url=http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf| title=Earth’s Annual Global Mean Energy Budget| first=J. T.| last=Kiehl| coauthors= Kevin E. Trenberth| format=PDF | journal=Bulletin of the American Meteorological Society| pages=197–208| volume=78| issue=2| month=February| year=1997| accessdate=2006-05-01| doi=10.1175/1520-0477(1997)078<0197:EAGMEB>2.0.CO;2}}</ref><ref>{{cite web| url=http://www.realclimate.org/index.php?p=142| year=6 Apr 2005| title=Water vapour: feedback or forcing?| publisher=[[RealClimate]]| accessdate=2006-05-01}}</ref>
The issue is how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of some greenhouse gases.

Human activity since the industrial revolution has increased the concentration of various greenhouse gases, leading to increased [[radiative forcing]] from CO2, [[methane]], tropospheric [[ozone]], [[CFC]]s and [[nitrous oxide]]. [[Molecule]] for molecule, methane is a more effective greenhouse gas than [[carbon dioxide]], but its concentration is much smaller so that its total [[radiative forcing]] is only about a fourth of that from carbon dioxide. Some other naturally occurring gases contribute small fractions of the greenhouse effect; one of these, [[nitrous oxide]] (N2O), is increasing in concentration owing to human activity such as agriculture. The [[Greenhouse gas#Increase of greenhouse gases|atmospheric concentrations]] of CO2 and CH4 have increased by 31% and 149% respectively since the beginning of the [[industrial revolution]] in the mid-1700s. These levels are considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from [[ice core]]s.<ref>Neftel, A., E. Moor, H. Oeschger, and B. Stauffer. (1985). [http://www.nature.com/nature/journal/v315/n6014/abs/315045a0.html "Evidence from polar ice cores for the increase in atmospheric CO2 in the past two centuries"]. ''Nature'' 315:45-47.</ref> From less direct geological evidence it is believed that CO2 values this high were last attained 20 million years ago.<ref>
{{cite journal| first=Paul N.| last=Pearson| coauthors=Palmer, Martin R.| journal=[[Nature (journal)|Nature]]| title= Atmospheric carbon dioxide concentrations over the past 60 million years| date=[[2000-08-17]]| volume=406| issue=6797| pages=695–699| url=http://www.nature.com/nature/journal/v406/n6797/abs/406695a0.html| doi=10.1038/35021000| format= abstract}}
</ref>
[[Fossil fuel]] burning has produced approximately three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, in particular [[deforestation]].<ref>
{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/006.htm |title=Summary for Policymakers |work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2007-01-18 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}
</ref>

The present atmospheric concentration of CO2 is about 385 parts per million ([[parts-per notation|ppm]]) by volume.<ref>
{{cite web | title = Trends in Atmospheric Carbon Dioxide – Mauna Loa | last = Tans | first = Pieter | url = http://www.esrl.noaa.gov/gmd/ccgg/trends/ | publisher = [[National Oceanic and Atmospheric Administration]] | accessdate = 2008-02-15}}
</ref> Human activities have caused the atmospheric concentrations of carbon dioxide and methane to be higher today than at any point during the last 650,000 years<ref name="CCinfo">{{cite web | title = Climate Change: Basic Information | publisher = [[United States Environmental Protection Agency]] | url = http://epa.gov/climatechange/basicinfo.html | accessdate = 2007-02-09 | date = [[2006-12-14]] | quote = In common usage, 'global warming' often refers to the warming that can occur as a result of increased emissions of greenhouse gases from human activities.}}</ref> .
Future CO2 levels are expected to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, [[sociology|sociological]], [[technology|technological]], and natural developments, but may be ultimately limited by the availability of fossil fuels. The IPCC [[Special Report on Emissions Scenarios]] gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.<ref>
{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/123.htm |last = Prentice |first = I. Colin |coauthors = ''et al.'' |title = 3.7.3.3 SRES scenarios and their implications for future CO2 concentration |work = Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2007-04-28 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}
</ref>
Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if [[coal]], [[tar sands]] or [[methane clathrate]]s are extensively used.<ref>
{{cite web |url=http://www.grida.no/climate/ipcc/emission/104.htm |title=4.4.6. Resource Availability |work=IPCC Special Report on Emissions Scenarios |accessdate=2007-04-28 |publisher=[[Intergovernmental Panel on Climate Change]]}}
</ref>

Inasmuch as the greenhouse effect is due to human activity, it is a [[forcing]] effect that is separate from forcing due to climate variability.

===Stored methane releases===
====Thawing permafrost====
{{main|Arctic methane release}}
Recent research carried out in 2008 in the Siberian Arctic has shown millions of tons of the greenhouse gas methane being released, apparently through perforations in the [[Arctic Ocean]]'s seabed permafrost,<ref>Compare: [http://www.mbari.org/news/news_releases/2007/paull-plfs.html Methane bubbling through seafloor creates undersea hills], [[Monterey Bay Aquarium Research Institute]], 5 February 2007</ref> with concentrations in some regions reaching up to 100 times above normal.<ref>{{cite web|url=http://www.independent.co.uk/environment/climate-change/exclusive-the-methane-time-bomb-938932.html|title=Exclusive: The methane time bomb|last=Connor|first=Steve|date=September 23, 2008|publisher=[[The Independant]]|accessdate=2008-10-03}}</ref><ref>{{cite web|url=http://www.independent.co.uk/news/science/hundreds-of-methane-plumes-discovered-941456.html|title=Hundreds of methane 'plumes' discovered|last=Connor|first=Steve|date=September 25, 2008|publisher=[[The Independant]]|accessdate=2008-10-03}}</ref> Current methane release has previously been estimated at 0.5 [[megatonne]]s (Mt) per year.<ref>N. Shakhova, I. Semiletov, A. Salyuk, D. Kosmach, and N. Bel’cheva (2007), [http://www.cosis.net/abstracts/EGU2007/01071/EGU2007-J-01071.pdf?PHPSESSID=e Methane release on the Arctic East Siberian shelf], ''Geophysical Research Abstracts'', '''9''', 01071</ref> Shakhova et al (2008) estimate that not less than 1,400 [[gigatonne]]s (Gt) of Carbon is presently locked up as methane and methane hydrates under the Arctic submarine permafrost, and 5-10% of that area is subject to puncturing by open [[talik]]s. They conclude that "release of up to 50 [[gigatonne]]s (Gt) of predicted amount of hydrate storage [is] highly possible for abrupt release at any time". That would increase the methane content of the planet's atmosphere by a factor of twelve,<ref>N. Shakhova, I. Semiletov, A. Salyuk, D. Kosmach (2008), [http://www.cosis.net/abstracts/EGU2008/01526/EGU2008-A-01526.pdf Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates?], [[European Geophysical Union|EGU]] General Assembly 2008, ''Geophysical Research Abstracts'', '''10''', EGU2008-A-01526</ref><ref>Volker Mrasek, [http://www.spiegel.de/international/world/0,1518,547976,00.html A Storehouse of Greenhouse Gases Is Opening in Siberia], ''[[Der Spiegel|Spiegel International Online]]'', 17 April 2008</ref> equivalent in greenhouse effect to a doubling in the current level of CO2. Land-based [[permafrost]] in the Siberian Arctic was also recently observed to be releasing large amounts of methane, estimated at over 4 million tons.<ref>{{cite web|url=http://www.mywire.com/a/EnvironmentNewsService/Melting-Russian-Permafrost-Could-Accelerate/1800717?ba=a&bi=17&bp=13|title=Melting Russian Permafrost Could Accelerate Global Warming|date=2006-9-7|publisher=MyWire: Environmental News Service|accessdate=2008-10-18}}</ref>

====Clathrate gun hypothesis====
{{main|Clathrate gun hypothesis}}
[[Methane clathrate]], also known as [[methane hydrate]], was once believed to only exist in space, as extremes of cold are required for its formation. Around 6.4 trillion tonnes (6.4 [[teratonne]]s/Tt) of methane<ref>Jaschek, C. & Jaschek, M. (1992) Astron. Astrophys., 95, p. 535</ref> is trapped in deposits of methane clathrate on the deep ocean floor<ref>Buffett, B.. "Global inventory of methane clathrate: sensitivity to changes in the deep ocean.". 185-199 Earth Planet. Sci. Lett. 227 (2004)</ref>. The [[Clathrate gun hypothesis]] states that warmer deep ocean temperatures can release the methane (CH4) from the deep ocean deposits of methane clathrate<ref name="CH4GX">James P. Kennett, Kevin G. Cannariato, Ingrid L. Hendy, and Richard J. Behl, (2003) ''Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis'', Washington, DC: [[American Geophysical Union]]. ISBN 0875902960</ref>. It is theorized that this was responsible for two extinction events in earth's history; the Permian-Triassic extinction event<ref name="CH4GX" /><ref>[http://www.bbc.co.uk/science/horizon/2002/dayearthdied.shtml The Day The Earth Nearly Died], ''BBC [[Horizon (TV series)|Horizon]]'', 2002</ref> and the [[Paleocene-Eocene Thermal Maximum]]. A concentration of 5-15% methane in the atmosphere, which would occur at and around the area of a CH4 release, is explosive<ref>[http://pangea.stanford.edu/Oceans/GES205/methaneGeology.pdf Methane Geology] Stanford.edu</ref>; the products of such an explosion would be 2 parts H2O to one of CO2. CH4 dissipates faster than carbon dioxide (CO2), but even after 20 years has a 62 times greater [[Global warming potential]] index.

==Solar variation==
{{main|Solar variation}}
[[Image:Solar-cycle-data.png|thumb|280px|right|Solar variation over the last thirty years.]]
Some other [[hypotheses]] departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity.<ref name="Svensmark2007">{{cite journal | first=Henrik | last=Svensmark | authorlink=Henrik Svensmark | year = 2007 | month = February | title = Cosmoclimatology: a new theory emerges | journal = Astronomy & Geophysics | volume = 48 | issue = 1 | pages = 18–24 | doi = 10.1111/j.1468-4004.2007.48118.x | url=http://www.spacecenter.dk/research/sun-climate/Scientific%20work%20and%20publications/svensmark_2007cosmoClimatology.pdf}}</ref><ref>{{cite web | url=http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch02.pdf | last=Forster | first=Piers | coauthors=''et al.'' | format=[[Portable Document Format|PDF]] | title=Changes in Atmospheric Constituents and in Radiative Forcing | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | pages=188-193 | accessdate=2007-09-17 | date=[[2007-02-05]] | publisher=[[Intergovernmental Panel on Climate Change]]}}</ref><ref>
{{cite journal |last=Bard |first=Edouard |coauthors=Frank, Martin |date=[[2006-06-09]] |title=Climate change and solar variability: What's new under the sun? |journal=Earth and Planetary Science Letters |volume=248 |issue=1-2 |pages=1–14 |url=http://www.ifm-geomar.de/fileadmin/personal/fb1/p-oz/mfrank/Bard_and_Frank_2006.pdf |accessdate= 2007-09-17 |doi=10.1016/j.epsl.2006.06.016) |doi_brokendate=2008-06-25|format=PDF}}</ref>

A paper by Peter Stott and other researchers suggests that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated.<ref>{{Cite journal | first=Peter A. | last=Stott | coauthors=''et al.'' | title=Do Models Underestimate the Solar Contribution to Recent Climate Change? | date=[[2003-12-03]] | journal=[[Journal of Climate]] | volume=16 | issue=24 | pages=4079–4093 | doi=10.1175/1520-0442(2003)016<4079:DMUTSC>2.0.CO;2 | accessdate=2007-04-16 | url=http://climate.envsci.rutgers.edu/pdf/StottEtAl.pdf | year=2003}}</ref>
They nevertheless conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming since the mid-20th century is likely attributable to the increases in greenhouse gases.

Two researchers at [[Duke University]], Bruce West and Nicola Scafetta, have estimated that the Sun may have contributed about 45–50 percent of the increase in the average global surface temperature over the period 1900–2000, and about 25–35 percent between 1980 and 2000.<ref>
{{cite journal | first=Nicola | last=Scafetta | coauthors=West, Bruce J. | title=Phenomenological solar contribution to the 1900–2000 global surface warming | url = http://www.fel.duke.edu/~scafetta/pdf/2005GL025539.pdf | format = [[Portable Document Format|PDF]] | date=[[2006-03-09]] | journal=[[Geophysical Research Letters]] | volume=33 | issue=5 | id=L05708 | doi=10.1029/2005GL025539 | accessdate=2007-05-08 | pages=L05708}}
</ref>

A different hypothesis is that variations in [[solar variation|solar output]], possibly amplified by cloud seeding via [[galactic cosmic ray]]s, may have contributed to recent warming.<ref>{{cite journal | first=Nigel | last=Marsh | coauthors=Henrik, Svensmark | title=Cosmic Rays, Clouds, and Climate | journal=Space Science Reviews | volume=94 | number=1–2 | pages=215–230 | year=2000 | month=November | url=http://www.dsri.dk/~hsv/SSR_Paper.pdf | format=[[Portable Document Format|PDF]] | doi=10.1023/A:1026723423896 | accessdate=2007-04-17}}
</ref> It suggests magnetic activity of the sun is a crucial factor which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.<ref>{{cite journal |last=Svensmark |first=Henrik |authorlink=Henrik Svensmark |year=2000 | month=July |format=[[Portable Document Format|PDF]] |title=Cosmic Rays and Earth's Climate |journal=Space Science Reviews |volume=93 |issue=1-2 |pages=175–185 |url=http://winnetou.lcd.lu/physique/OSCIE2003/global_warming/Cosmic_rays_and_Earth_Climate_new_sven0606.pdf |accessdate= 2007-09-17 |doi=10.1023/A:1026592411634}}</ref>

One predicted effect of an increase in solar activity would be a warming of most of the [[stratosphere]], whereas an increase in greenhouse gases should produce cooling there.<ref>{{cite web | url= http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter9.pdf | format=[[Portable Document Format|PDF]] | title=Understanding and Attributing Climate Change | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2008-02-01 | publisher=[[Intergovernmental Panel on Climate Change]] | last=Hegerl | first=Gabriele C. | coauthors=''et al.'' | pages=675}}
</ref> The observed trend since at least 1960 has been a cooling of the lower stratosphere.<ref>{{cite web|title=Climate Change 2001:Working Group I: The Scientific Basis (Fig. 2.12)|url=http://www.grida.no/climate/ipcc_tar/wg1/fig2-12.htm|year=2001|accessdate=2007-05-08}}
</ref> [[Ozone depletion|Reduction of stratospheric ozone]] also has a cooling influence, but substantial ozone depletion did not occur until the late 1970s.<ref>[http://www.nas.nasa.gov/About/Education/Ozone/history.html Ozone History]</ref> Solar variation combined with changes in [[volcano|volcanic activity]] probably did have a warming effect from pre-industrial times to 1950, but a cooling effect since.<ref name="grida7" /> In 2006, Peter Foukal and other researchers from the United States, [[Germany]], and [[Switzerland]] found no net increase of solar brightness over the last 1,000 years. [[Solar cycle]]s led to a small increase of 0.07 percent in brightness over the last 30 years. This effect is too small to contribute significantly to global warming.<ref>
{{cite journal | first=Peter | last=Foukal | coauthors=''et al.'' | title=Variations in solar luminosity and their effect on the Earth's climate. | date=[[2006-09-14]] | journal=[[Nature]] | accessdate=2007-04-16 | url=http://www.nature.com/nature/journal/v443/n7108/abs/nature05072.html | doi=10.1038/nature05072 | format=abstract | volume=443 | pages=161}}</ref><ref>{{cite pressrelease | title=Changes in Solar Brightness Too Weak to Explain Global Warming | url=http://www.ucar.edu/news/releases/2006/brightness.shtml#| publisher=[[National Center for Atmospheric Research]] | date=[[2006-09-14]] | accessdate=2007-07-13 }}</ref> One paper by Mike Lockwood and Claus Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in [[cosmic ray]]s.<ref>{{cite journal | last = Lockwood | first = Mike
| authorlink = | coauthors = Claus Fröhlich | title = Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature | journal = Proceedings of the Royal Society A | volume =463 | issue = | pages =2447 | date = | quote = Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified. | url = http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf | doi = 10.1098/rspa.2007.1880 | id = | accessdate = 2007-07-21 |format=PDF}}</ref> [[Henrik Svensmark]] and [[Eigil Friis-Christensen]], the main proponents of [[cloud seeding]] by galactic cosmic rays, disputed this criticism of their hypothesis.<ref>[http://www.spacecenter.dk/publications/scientific-report-series/Scient_No._3.pdf/view Reply to Lockwood and Fröhlich - The persistent role of the Sun in climate forcing — Spacecenter]</ref> A 2007 paper found that in the last 20 years there has been no significant link between changes in cosmic rays coming to Earth and cloudiness and temperature.<ref>{{cite news | publisher=[[BBC News Online]] | title='No Sun link' to climate change | url=http://news.bbc.co.uk/2/hi/science/nature/7327393.stm | author=Richard Black | date=April 3, 2008}}</ref><ref>{{cite journal | doi=10.1088/1748-9326/3/2/024001 | title=Testing the proposed causal link between cosmic rays and cloud cover | author=T Sloan and A W Wolfendale | journal=Environ. Res. Lett. | volume=3 | page=024001 | year=2008 | pages=024001}}</ref><ref>[http://arxiv.org/abs/0803.2298 preprint of this paper can be found here]</ref>

==Forcing and feedback==
[[Image:Radiative-forcings.svg|thumb|280px|right| Components of the current [[radiative forcing]] as estimated by the [[IPCC Fourth Assessment Report]].]]
The forces that drive climate change are said to be operating in a system called forcing. None of the effects of forcing are instantaneous. The [[Volumetric heat capacity|thermal inertia]] of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. [[Climate commitment]] studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about {{nowrap|0.5 °C}} {{nowrap|(0.9 °F)}} would still occur.<ref>
{{cite journal |last=Meehl |first=Gerald A. |coauthors=''et al.'' |date=[[2005-03-18]] |title=How Much More Global Warming and Sea Level Rise |journal=[[Science (journal)|Science]] |volume=307 |issue=5716 |pages=1769–1772 |doi=10.1126/science.1106663 |url=http://www.sciencemag.org/cgi/reprint/307/5716/1769.pdf | format=[[Portable Document Format|PDF]] | accessdate=2007-02-11 |pmid=15774757}}
</ref>

===Climate variability===
The Earth's climate changes in response to external forcing, including [[greenhouse gases]], variations in its orbit around the [[Sun]] ([[orbital forcing]]),<ref>{{cite journal |last=Berger |first=A. |coauthors=''et al.'' |date=[[2005-12-10]] |title=On the origin of the 100-kyr cycles in the astronomical forcing |journal=Paleoceanography |volume=20 |issue=4 |pages= |id=PA4019 |url=http://www.agu.org/pubs/crossref/2005/2005PA001173.shtml |accessdate= 2007-11-05 |doi=10.1029/2005PA001173, |doi_brokendate=2008-06-25}}</ref><ref>{{cite journal |last=Genthon |first=C. |coauthors=''et al.'' |date=[[1987-10-01]] |title=Vostok Ice Core - Climatic response to CO2 and orbital forcing changes over the last climatic cycle |journal=[[Nature (journal)|Nature]] |volume=329 |issue=6138 |pages=414–418 |url=http://www.nature.com/nature/journal/v329/n6138/abs/329414a0.html |accessdate= 2007-11-05 |doi=10.1038/329414a0 |format=abstract}}</ref><ref>{{cite journal |last=Alley |first=Richard B. |coauthors=''et al.'' |year=2002 |month=January |title=A northern lead in the orbital band: north-south phasing of Ice-Age events |journal=Quaternary Science Reviews |volume=21 |issue=1-3 |pages=431–441 |url=http://www.ingentaconnect.com/content/els/02773791/2002/00000021/00000001/art00072 |accessdate= 2007-11-05 |doi=10.1016/S0277-3791(01)00072-5}}</ref> changes in [[solar luminosity]], and [[volcano|volcanic]] eruptions;<ref>Robock, Alan, and Clive Oppenheimer, Eds., 2003: Volcanism and the Earth’s Atmosphere, Geophysical Monograph 139, American Geophysical Union, Washington, DC, 360 pp.</ref> all examples of the earth's own variation in temperatures, for which the [[UNFCCC]] uses the term climate variability.

===Feedback===
{{main|Effects of global warming}}
When a warming trend results in effects that induce further warming, it is known as a positive feedback; when the effects induce cooling, the process is referred to as a negative feedback. The primary positive feedback involves water vapor. The primary negative feedback is temperature-radiation: as the temperature of a body increases, the emitted radiation increases with the fourth power of its [[absolute temperature]].<ref>[http://www.britannica.com/EBchecked/topic/564843/Stefan-Boltzmann-law "Stefan-Boltzmann Law", Britannica Online]</ref> This provides a powerful negative feedback which stabilizes the climate system over time.

One of the most pronounced positive feedback effects relates to the evaporation of water. If the atmosphere is warmed, the [[saturation vapour pressure]] increases, and the quantity of water vapor in the atmosphere will tend to increase. Since water vapor is a greenhouse gas, the increase in water vapor content makes the atmosphere warm further; this warming causes the atmosphere to hold still more water vapor (a [[positive feedback]]), and so on until other processes stop the feedback loop. The result is a much larger greenhouse effect than that due to CO2 alone. Although this feedback process causes an increase in the absolute moisture content of the air, the [[relative humidity]] stays nearly constant or even decreases slightly because the air is warmer.<ref name="soden1">{{cite journal| first= Brian J. | last= Soden | coauthors= Held, Isacc M. | journal= [[Journal of Climate]] | title= An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models | date= [[2005-11-01]] | volume= 19 | issue= 14 | url= http://www.gfdl.noaa.gov/reference/bibliography/2006/bjs0601.pdf | format= [[Portable Document Format|PDF]] | accessdate= 2007-04-21 | quote=Interestingly, the true feedback is consistently weaker than the constant relative humidity value, implying a small but robust reduction in relative humidity in all models on average" "clouds appear to provide a positive feedback in all models | pages= 3354–3360 | doi= 10.1175/JCLI3799.1}}</ref> This feedback effect can only be reversed slowly as CO2 has a long average [[Greenhouse gas#Removal from the atmosphere and global warming potential|atmospheric lifetime]].

Feedback effects due to clouds are an area of ongoing research. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect. Whether the net effect is warming or cooling depends on details such as the [[list of cloud types|type]] and altitude of the cloud. These details are difficult to represent in climate models, in part because clouds are much smaller than the spacing between points on the computational grids of climate models.<ref name="soden1" />

{{Double image stack|right|Northern Hemisphere Sea Ice Extent Anomalies.png|Southern Hemisphere Sea Ice Extent Anomalies.png|280|Northern Hemisphere ice trends|Southern Hemisphere ice trends.}}

A subtler feedback process relates to changes in the [[lapse rate]] as the atmosphere warms. The atmosphere's temperature decreases with height in the [[troposphere]]. Since emission of infrared radiation varies with the fourth power of temperature, [[longwave radiation]] emitted from the upper atmosphere is less than that emitted from the lower atmosphere. Most of the radiation emitted from the upper atmosphere escapes to space, while most of the radiation emitted from the lower atmosphere is re-absorbed by the surface or the atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere's rate of temperature decrease with height: if the rate of temperature decrease is greater the greenhouse effect will be stronger, and if the rate of temperature decrease is smaller then the greenhouse effect will be weaker. Both theory and climate models indicate that with increased greenhouse gas content the rate of temperature decrease with height will be reduced, producing a negative ''lapse rate feedback'' that weakens the greenhouse effect. Measurements of the rate of temperature change with height are very sensitive to small errors in observations, making it difficult to establish whether the models agree with observations.<ref>[http://www.nap.edu/catalog.php?record_id=10850 Panel on Climate Change Feedbacks, Climate Research Committee, National Research Council, 2004: Understanding Climate Change Feedbacks.]</ref>

Another important feedback process is ice-[[albedo]] feedback.<ref>{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/295.htm |last = Stocker |first = Thomas F. |coauthors = ''et al.'' |title = 7.5.2 Sea Ice |work = Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2007-02-11 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}</ref> When global temperatures increase, ice near the poles melts at an increasing rate. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues.

Warming is also the triggering variable for the release of methane from sources both on land and on the deep ocean floor, making both of these possible feedback effects. Thawing [[permafrost]], such as the frozen [[peat]] [[bog]]s in [[Siberia]], creates a [[positive feedback]] due to release of CO2 and CH4.<ref>{{cite news | first=Ian | last=Sample | title=Warming Hits 'Tipping Point' | date=[[2005-08-11]] | url=http://www.guardian.co.uk/climatechange/story/0,12374,1546824,00.html | publisher=[[The Guardian]] | accessdate=2007-01-18}}</ref> Methane discharge from permafrost is presently under intensive study. Warmer deep ocean temperatures, likewise, could release the greenhouse gas [[methane]] from the 'frozen' state of the vast deep ocean deposits of [[methane clathrate]]/[[methane hydrate]], according to the [[Clathrate Gun Hypothesis]],

Ocean ecosystems' ability to sequester carbon are expected to decline as it warms. This is because the resulting low nutrient levels of the [[mesopelagic zone]] (about 200 to 1000 m depth) limits the growth of [[diatom]]s in favor of smaller [[phytoplankton]] that are poorer [[biological pump]]s of carbon.<ref>{{cite journal |last=Buesseler |first=Ken O. |coauthors=''et al.'' |date=[[2007-04-27]] |title=Revisiting Carbon Flux Through the Ocean's Twilight Zone |journal=[[Science (journal)|Science]] |volume=316 |issue=5824 |pages=567–570 |url=http://www.sciencemag.org/cgi/content/abstract/316/5824/567 |accessdate= 2007-11-16 |format=abstract |doi=10.1126/science.1137959 |pmid=17463282}}</ref>

==Temperature changes==
{{main|Temperature record}}
===Recent===
[[Image:2000 Year Temperature Comparison.png|thumb|280px|right|Two millennia of mean surface temperatures according to different reconstructions, each smoothed on a decadal scale. The unsmoothed, annual value for 2004 is also plotted for reference.]]
Global temperatures have increased by {{nowrap|0.75 °C (1.35 °F)}} relative to the period 1860–1900, according to the [[instrumental temperature record]]. This measured temperature increase is not significantly affected by the [[urban heat island]] effect.<ref>[http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf Working group I, section 3.2.2.2 of the 2007 IPPC page 243]</ref> Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade).<ref>{{cite journal| last = Smith | first = Thomas M. | coauthors= Reynolds, Richard W. | title = A Global Merged Land–Air–Sea Surface Temperature Reconstruction Based on Historical Observations (1880–1997) | journal = [[Journal of Climate]] |volume = 18 |issue = 12 | issn = 0894-8755 | pages = 2021–2036 | url = http://www.ncdc.noaa.gov/oa/climate/research/Smith-Reynolds-dataset-2005.pdf | format = [[Portable Document Format|PDF]] | date = [[2005-05-15]] | accessdate = 2007-03-14 | doi = 10.1175/JCLI3362.1}}</ref> Temperatures in the lower [[troposphere]] have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to [[satellite temperature measurements]]. Temperature is believed to have been relatively stable over the [[Temperature record of the past 1000 years|one or two thousand years]] before 1850, with possibly regional fluctuations such as the [[Medieval Warm Period]] or the [[Little Ice Age]].{{Fact|date=June 2008}}

Sea temperatures increase more slowly than those on land both because of the larger effective heat capacity of the oceans and because the ocean can lose heat by evaporation more readily than the land.<ref>{{cite journal|title=Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations|author = Rowan T. Sutton, Buwen Dong, Jonathan M. Gregory|journal=[[Geophysical Research Letters]]|volume=34|url=http://www.agu.org/pubs/crossref/2007/2006GL028164.shtml|doi=10.1029/2006GL028164|year=2007|accessdate=2007-09-19|pages=L02701}}</ref> The [[Northern Hemisphere]] has more land than the [[Southern Hemisphere]], so it warms faster. The Northern Hemisphere also has extensive areas of seasonal snow and sea-ice cover subject to the ice-albedo feedback. More greenhouse gases are emitted in the Northern than Southern Hemisphere, but this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix between hemispheres.<ref>[http://www.grida.no/CLIMATE/IPCC_TAR/WG1/pdf/TAR-04.PDF]</ref>

Based on estimates by [[NASA]]'s [[Goddard Institute for Space Studies]], 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree.<ref>{{cite web |url= http://data.giss.nasa.gov/gistemp/2005/ |last= Hansen | first = James E. |authorlink= James Hansen |coauthors= ''et al.'' |title= Goddard Institute for Space Studies, GISS Surface Temperature Analysis |accessdate=2007-01-17 |date= [[2006-01-12]] |publisher= NASA [[Goddard Institute for Space Studies]]}}</ref> Estimates prepared by the [[World Meteorological Organization]] and the [[Climatic Research Unit]] concluded that 2005 was the second warmest year, behind 1998.<ref>
{{cite web |url= http://www.cru.uea.ac.uk/cru/press/2005-12-WMO.pdf |title= Global Temperature for 2005: second warmest year on record |accessdate=2007-04-13 |date= [[2005-12-15]] |publisher= [[Climatic Research Unit]], School of Environmental Sciences, University of East Anglia |format = [[Portable Document Format|PDF]]}}</ref><ref>{{cite web |url=http://grdc.bafg.de/servlet/is/4226/Pressemitteilung-WMO-23-Dez-05-743_E1.pdf |format=[[Portable Document Format|PDF]] |title=WMO STATEMENT ON THE STATUS OF THE GLOBAL CLIMATE IN 2005 |accessdate=2007-04-13 |date=[[2005-12-15]] |publisher=[[World Meteorological Organization]]}}</ref> Temperatures in 1998 were unusually warm because the strongest [[El Niño-Southern Oscillation]] in the past century occurred during that year.<ref name="Changnon2000">{{cite book |title=El Niño, 1997-1998: The Climate Event of the Century |last=Changnon |first=Stanley A. |authorlink= |coauthors=Bell, Gerald D. |year=2000 |publisher=Oxford University Press |location=London |isbn=0195135520 |pages= }}</ref>

Anthropogenic emissions of other [[pollutant]]s—notably sulfate [[aerosol]]s—can exert a cooling effect by increasing the reflection of incoming sunlight. This partially accounts for the cooling seen in the temperature record in the middle of the twentieth century,<ref>{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/462.htm |last = Mitchell |first = J. F. B. |coauthors = ''et al.'' |title = 12.4.3.3 Space-time studies |work = Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2007-01-04 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}</ref> though the cooling may also be due in part to natural variability. [[James Hansen]] and colleagues have proposed that the effects of the products of fossil fuel combustion—CO2 and aerosols—have largely offset one another, so that warming in recent decades has been driven mainly by non-CO2 greenhouse gases.<ref name="pmid10944197">{{cite journal |author=Hansen J, Sato M, Ruedy R, Lacis A, Oinas V |title=Global warming in the twenty-first century: an alternative scenario |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=97 |issue=18 |pages=9875–80 |year=2000 |month=August |pmid=10944197 |doi=10.1073/pnas.170278997}}</ref>

Paleoclimatologist [[William Ruddiman]] has argued that human influence on the global climate began around 8,000 years ago with the start of forest clearing to provide land for agriculture and 5,000 years ago with the start of Asian rice irrigation.<ref>{{cite journal |last=Ruddiman |first=William F. |authorlink=William Ruddiman |title=How Did Humans First Alter Global Climate? |volume=292 |issue=3 |journal=[[Scientific American]] |month=March | year=2005 |pages=46–53 |url=http://ccr.aos.wisc.edu/news/0305046.pdf |format=[[Portable Document Format|PDF]] |accessdate=2007-03-05}}</ref>Ruddiman's interpretation of the historical record, with respect to the methane data, has been disputed.<ref>{{cite journal |last=Schmidt |first=Gavin |authorlink=Gavin Schmidt |coauthors=''et al.'' |date=[[2004-12-10]] |title=A note on the relationship between ice core methane concentrations and insolation |journal=[[Geophysical Research Letters]] |volume=31 |issue=23 |id=L23206 |doi=10.1029/2004GL021083 |url=http://pubs.giss.nasa.gov/abstracts/2004/Schmidt_etal_2.html |accessdate=2007-03-05 |pages=L23206 |format=abstract}}</ref>

===Pre-human climate variations===
{{See|Paleoclimatology}}
{{See also|Snowball Earth}}
[[Image:Ice Age Temperature.png|thumb|250px|right|Curves of reconstructed temperature at two locations in Antarctica and a global record of variations in glacial ice volume. Today's date is on the left side of the graph.]]
Earth has experienced warming and cooling many times in the past. The recent Antarctic [[European Project for Ice Coring in Antarctica|EPICA]] ice core spans 800,000 years, including eight glacial cycles timed by [[Milankovitch cycles|orbital variations]] with [[interglacial]] warm periods comparable to present temperatures.<ref>{{cite journal | first=James | last=Hansen | coauthors=''et al.'' | url=http://www.pnas.org/cgi/reprint/103/39/14288.pdf | title=Global temperature change | journal=[[Proceedings of the National Academy of Sciences|PNAS]] | volume=103 | number=39 | pages=14288–14293 | date=[[2006-09-26]] | format=[[Portable Document Format|PDF]] | accessdate=2007-04-20 | doi=10.1073/pnas.0606291103 | pmid=17001018}}</ref>

A rapid buildup of greenhouse gases amplified warming in the early [[Jurassic]] period (about 180 million years ago), with average temperatures rising by 5 °C (9 °F). Research by the [[Open University]] indicates that the warming caused the rate of rock [[weathering]] to increase by 400%. As such weathering locks away carbon in [[calcite]] and [[dolomite]], CO2 levels dropped back to normal over roughly the next 150,000 years.<ref>{{cite journal | last = Cohen | first = Anthony S. | coauthors = ''et al.'' | year = 2004 | month = February | title = Osmium isotope evidence for the regulation of atmospheric CO2 by continental weathering | journal = [[Geology (journal)|Geology]] | volume = 32 | issue = 2 | pages = 157–160 | doi = 10.1130/G20158.1 | url = http://sheba.geo.vu.nl/~vonh/imagesanddata/data/Cohenetal2004.pdf | format = [[Portable Document Format|PDF]] | accessdate = 2007-03-04}}</ref>

Sudden releases of methane from [[clathrate compound]]s (the [[clathrate gun hypothesis]]) have been hypothesized as both a cause for and an effect of other warming events in the distant past, including the [[Permian–Triassic extinction event]] (about 251 million years ago) and the [[Paleocene–Eocene Thermal Maximum]] (about 55 million years ago).

==Climate models==
{{main|Global climate model}}
{{Double image stack|right|Global Warming Predictions.png|Global Warming Predictions Map.jpg|250|Calculations of global warming prepared in or before 2001 from a range of [[climate model]]s under the [[Special Report on Emissions Scenarios|SRES]] A2 emissions scenario, which assumes no action is taken to reduce emissions.|The geographic distribution of surface warming during the 21st century calculated by the [[HadCM3]] climate model if a business as usual scenario is assumed for economic growth and greenhouse gas emissions. In this figure, the globally averaged warming corresponds to 3.0 °C (5.4 °F).}}

Scientists have studied global warming with [[computer models]] of the climate. These models are based on physical principles of fluid dynamics, [[radiative transfer]], and other processes, with simplifications being necessary because of limitations in computer power and the [[complex system|complexity]] of the climate system. All modern climate models include an atmospheric model that is coupled to an ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes.<ref>{{cite web | url= http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter7.pdf | format=[[Portable Document Format|PDF]] | title=Chapter 7, "Couplings Between Changes in the Climate System and Biogeochemistry" | work=Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2008-02-21 | date=[[2007-02-05]] | publisher=[[Intergovernmental Panel on Climate Change]]}}</ref> These models predict that the effect of adding greenhouse gases is to produce a warmer climate.<ref>{{cite web |url=http://books.google.com/books?id=sx6DFr8rbpIC&dq=robert+lanza&printsec=frontcover&source=web&ots=S7MXYzoDqR&sig=jfUo33FtVZ3PSUS2fcc_EtawEnQ |last = Hansen |first = James |title = Climatic Change: Understanding Global Warming |work = One World: The Health & Survival of the Human Species in the 21st century |accessdate=2007-08-18 | year = 2000 |publisher= Health Press}}</ref> However, even when the same assumptions of future greenhouse gas levels are used, there still remains a considerable range of [[climate sensitivity]].

Including uncertainties in future greenhouse gas concentrations and climate modeling, the IPCC anticipates a warming of {{nowrap|1.1 °C to 6.4 °C}} {{nowrap|(2.0 °F to 11.5 °F)}} by the end of the 21st century, relative to 1980–1999.<ref name="grida7" /> Models have also been used to help investigate the [[Attribution of recent climate change|causes of recent climate change]] by comparing the observed changes to those that the models project from various natural and human-derived causes.

Current climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate.<ref>{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/007.htm |title=Summary for Policymakers |work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2007-04-28 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}</ref> These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made [[greenhouse gas]] emissions.

Global climate model projections of future climate are forced by imposed greenhouse gas emission scenarios, most often from the IPCC [[Special Report on Emissions Scenarios]] (SRES). Less commonly, models may also include a simulation of the [[carbon cycle]]; this generally shows a positive feedback, though this response is uncertain (under the A2 SRES scenario, responses vary between an extra 20 and 200 ppm of CO2). Some observational studies also show a positive feedback.<ref>{{cite journal |last=Torn |first=Margaret |coauthors=Harte, John |date=[[2006-05-26]] |title=Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming |journal=[[Geophysical Research Letters]] |volume=33 |issue=10 |id=L10703 |url=http://www.agu.org/pubs/crossref/2006/2005GL025540.shtml |accessdate=2007-03-04 |doi=10.1029/2005GL025540, |doi_brokendate=2008-06-25}}</ref><ref>{{cite journal |last=Harte |first=John |coauthors=''et al.'' |date=[[2006-10-30]] |title=Shifts in plant dominance control carbon-cycle responses to experimental warming and widespread drought |journal=Environmental Research Letters |volume=1 |issue=1 |id=014001 |url=http://www.iop.org/EJ/article/1748-9326/1/1/014001/erl6_1_014001.html |accessdate=2007-05-02 |doi=10.1088/1748-9326/1/1/014001 |pages=014001}}</ref><ref>{{cite journal |last = Scheffer |first = Marten |coauthors = ''et al.'' |title = Positive feedback between global warming and atmospheric CO2 concentration inferred from past climate change. |journal = [[Geophysical Research Letters]] |volume = 33 |url = http://www.pik-potsdam.de/~victor/recent/scheffer_etal_T_CO2_GRL_in_press.pdf |doi = 10.1029/2005gl025044 |date = [[2006-05-26]] |accessdate = 2007-05-04 |pages = L10702|format=PDF}}</ref>

In May 2008, it was predicted that "global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming", based on the inclusion of ocean temperature observations.<ref>{{cite journal|url=http://www.nature.com/nature/journal/v453/n7191/abs/nature06921.html|title=Advancing decadal-scale climate prediction in the North Atlantic sector|author=N. S. Keenlyside, M. Latif, J. Jungclaus, L. Kornblueh2, E. Roeckner|date=May 1, 2008|pages=84-88|journal=[[Nature (journal)|Nature]]|issue=453|accessdate=2008-07-06|doi=10.1038/nature06921}}</ref>

The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.<ref>{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/271.htm |last = Stocker |first = Thomas F. |coauthors = ''et al.'' |title = 7.2.2 Cloud Processes and Feedbacks |work = Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2007-03-04 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}</ref>

A minor issue in climate modeling is the perceived mismatch between actual conditions and those predicted by the models. A 2007 study by [[David Douglass]], [[John Christy]], Benjamin Pearson and [[Fred Singer]] comparing the composite output of 22 leading global climate models with actual climate data found that the models do not accurately predict observed changes to the temperature profile in the tropical troposphere. The authors note that their conclusions contrast strongly with those of recent publications based on essentially the same data.<ref>{{cite journal| last=Douglass | first=David H. | authorlink = David Douglass | coauthors=''et al.'' | date=[[2007-12-05]] | title=A comparison of tropical temperature trends with model predictions | journal=International Journal of Climatology | volume=9999 | issue=9999 | doi=10.1002/joc.1651 | url=http://icecap.us/images/uploads/DOUGLASPAPER.pdf | format=[[Portable Document Format|PDF]] | accessdate=2008-05-12}}</ref> However, a 2008 paper, published by a 17-member team led by [[Ben Santer]] of [[Lawrence Livermore National Laboratory]], found serious flaws in the previous study, instead finding that any deviations were statistically insignificant.<ref>{{cite journal|last=Santer|first=B.D.|authorlink=Benjamin D. Santer|coauthors=''et al.''|date=2008-10-10|title=Consistency of modelled and observed temperature trends in the tropical troposphere|journal=International Journal of Climatology|volume=28|issue=13|doi=10.1002/joc.1756|url=https://publicaffairs.llnl.gov/news/news_releases/2008/NR-08-10-05-article.pdf|format=[[Portable Document Format|PDF]]|accessdate=2008-10-22}}</ref>

==Attributed and expected effects==
===Environmental===
{{main|Effects of global warming}}
[[Image:Glacier Mass Balance.png|right|thumb|280px|Sparse records indicate that glaciers have been retreating since the early 1800s. In the 1950s measurements began that allow the monitoring of glacial mass balance, reported to the [[World Glacier Monitoring Service|WGMS]] and the [[National Snow and Ice Data Center|NSIDC]].]]
Although it is difficult to connect specific weather events to global warming, an increase in global temperatures may in turn cause broader [[effects of global warming|changes]], including [[Glacier mass balance|glacial retreat]], [[Arctic shrinkage]], and worldwide [[sea level rise]]. Changes in the amount and pattern of [[precipitation (meteorology)|precipitation]] may result in [[flood]]ing and [[drought]]. There may also be changes in the frequency and intensity of [[extreme weather]] events. Other effects may include changes in agricultural yields, addition of new trade routes,<ref>{{cite news |first=Jennifer |last=Macey |title=Global warming opens up Northwest Passage |url=http://www.abc.net.au/news/stories/2007/09/19/2037198.htm?section=business |publisher=ABC News |date=September 19, 2007 |accessdate=2007-12-11}}</ref> reduced summer [[streamflow]]s, species [[extinction risk from climate change|extinctions]], and increases in the range of [[Vector (biology)|disease vectors]].

Some effects on both the [[natural environment]] and [[civilization|human life]] are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that [[Retreat of glaciers since 1850|glacier retreat]], [[Ice shelf#Ice shelf disruption|ice shelf disruption]] such as that of the [[Larsen Ice Shelf]], [[sea level rise]], changes in rainfall patterns, and increased intensity and frequency of [[Effects of global warming#More extreme weather|extreme weather events]], are being attributed in part to global warming.<ref name="tar_wg2">{{cite web |title = Climate Change 2001: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change |url = http://www.grida.no/climate/ipcc_tar/wg2/index.htm |publisher = [[Intergovernmental Panel on Climate Change]] |date = [[2001-02-16]] |accessdate = 2007-03-14}}</ref> While changes are expected for overall patterns, intensity, and frequencies, it is difficult to attribute specific events to global warming. Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and adverse health effects from warmer temperatures.<ref>{{cite journal |author=McMichael AJ, Woodruff RE, Hales S |title=Climate change and human health: present and future risks |journal=Lancet |volume=367 |issue=9513 |pages=859–69 |year=2006 |pmid=16530580 |doi=10.1016/S0140-6736(06)68079-3}}</ref>

Increasing deaths, displacements, and economic losses projected due to [[extreme weather]] attributed to global warming may be exacerbated by [[Population growth|growing population]] densities in affected areas, although temperate regions are projected to experience some benefits, such as fewer deaths due to cold exposure.<ref name="WGII SPM AR4">{{cite web |title = Summary for Policymakers |work = Climate Change 2007: Impacts, Adaptation and Vulnerability. Working Group II Contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report |url =http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-spm.pdf |format = [[Portable Document Format|PDF]] |publisher = [[Intergovernmental Panel on Climate Change]] |date = [[2007-04-13]] |accessdate = 2007-04-28}}</ref> A summary of probable effects and recent understanding can be found in the report made for the [[IPCC Third Assessment Report]] by Working Group II.<ref name="tar_wg2" /> The newer [[IPCC Fourth Assessment Report]] summary reports that there is observational evidence for an increase in intense [[tropical cyclone]] activity in the North [[Atlantic Ocean]] since about 1970, in correlation with the increase in sea surface temperature (see [[Atlantic Multidecadal Oscillation]]), but that the detection of long-term trends is complicated by the quality of records prior to routine [[satellite]] observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones.<ref name="grida7" />

Additional anticipated effects include sea level rise of {{nowrap|180 to 590 millimeters}} {{nowrap|(0.59 to 1.9 ft)}} in 2090-2100 relative to 1980-1999, <ref name="grida7" /> [[Climate change and agriculture|repercussions to agriculture]], [[Shutdown of thermohaline circulation|possible slowing of the thermohaline circulation]], reductions in the [[ozone layer]], increased intensity (but less frequent)<ref>{{cite journal|doi = 10.1038/ngeo202|title = Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions|year = 2008|author = Knutson, Thomas R.|journal = Nature Geoscience|volume = 1|pages = 359}}</ref> of [[Effects of global warming#More extreme weather|hurricanes and extreme weather events]], [[Ocean acidification|lowering]] of ocean [[pH]], and the spread of diseases such as [[malaria]] and [[dengue fever]]. One study predicts 18% to 35% of a sample of 1,103 animal and plant species would be [[extinction risk from climate change|extinct]] by 2050, based on future climate projections.<ref>{{cite journal |last= Thomas |first= Chris D. |coauthors= ''et al.'' |date= [[2004-01-08]] |title= Extinction risk from climate change |journal= [[Nature (journal)|''Nature'']] |volume= 427 |issue= 6970 |pages= 145–138 |doi= 10.1038/nature02121 |url= http://www.geog.umd.edu/resac/outgoing/GEOG442%20Fall%202005/Lecture%20materials/extinctions%20and%20climate%20change.pdf |format= [[Portable Document Format|PDF]] |accessdate= 2007-03-18}}</ref> However, few mechanistic studies have documented extinctions due to recent climate change<ref>{{cite journal |last= McLaughlin |first= John F. |coauthors= ''et al.'' |date= [[2002-04-30]] |title= Climate change hastens population extinctions |journal= [[Proceedings of the National Academy of Sciences|PNAS]] |volume= 99 |issue= 9 |pages= 6070–6074 |doi= 10.1073/pnas.052131199 |url= http://www.nd.edu/~hellmann/pnas.pdf |format= [[Portable Document Format|PDF]] |accessdate= 2007-03-29 |pmid= 11972020}}</ref> and one study suggests that projected rates of extinction are uncertain.<ref>{{cite journal |last=Botkin |first=Daniel B. |authorlink= |coauthors=''et al.'' |year=2007 |month=March |title=Forecasting the Effects of Global Warming on Biodiversity |journal=[[BioScience]] |volume=57 |issue=3 |pages=227–236 |doi=10.1641/B570306 |url=http://www.imv.dk/Admin/Public/DWSDownload.aspx?File=%2FFiles%2FFiler%2FIMV%2FPublikationer%2FFagartikler%2F2007%2F050307_Botkin_et_al.pdf |accessdate= 2007-11-30|format=PDF}}</ref>

Global warming is expected to increase the potential geographic range and virulence
of [[tropical disease]]s.<ref>[http://www.cbsnews.com/stories/2002/06/20/tech/main512920.shtml Global Warming May Spread Diseases, Study: Pathogens Invade New Areas As Temperatures Rise], CBS News</ref> Climate change could cause a major increase in insect-borne [[Infectious diseases|diseases]] such as [[malaria]] throughout [[Europe]], [[North America]] and North [[Asia]].<ref>[http://world.merinews.com/catFull.jsp;jsessionid=EAA582BA3E049534BABAA98C515DEF1F?articleID=137538 Global warming breeds malaria]</ref>

===Economic===
{{main|Economics of global warming|Low-carbon economy}}
[[Image:IPCC AR4 WGIII GHG concentration stabilization levels.png|thumb|right|280px|The projected temperature increase for a range of stabilization scenarios (the colored bands). The black line in middle of the shaded area indicates 'best estimates'; the red and the blue lines the likely limits. From the work of [[IPCC Fourth Assessment Report|IPCC AR4]].]]
Some economists have tried to estimate the aggregate net economic costs of damages from climate change across the globe. Such estimates have so far yielded no conclusive findings; in a survey of 100 estimates, the values ran from [[United States dollar|US$]]-10 per tonne of carbon (tC) (US$-3 per tonne of carbon dioxide) up to [[US$]]350/tC (US$95 per tonne of carbon dioxide), with a mean of US$43 per tonne of carbon (US$12 per tonne of carbon dioxide).<ref name="WGII SPM AR4" />

One widely publicized report on potential economic impact is the [[Stern Review]]; it suggests that extreme weather might reduce global [[gross domestic product]] by up to one percent, and that in a worst-case scenario global [[per capita]] consumption could fall 20 percent.<ref>{{cite web | url= http://news.bbc.co.uk/2/hi/business/6098362.stm | title = At-a-glance: The Stern Review | publisher = [[BBC]] |accessdate=2007-04-29 |date = [[2006-10-30]]}}</ref> The report's methodology, advocacy and conclusions have been criticized by many economists, primarily around the Review's assumptions of [[discounting]] and its choices of scenarios,<ref>Tol and Yohe (2006) "A Review of the Stern Review" ''World Economics'' '''7'''(4): 233-50. See also other critiques in ''World Economics'' '''7'''(4).</ref> while others have supported the general attempt to quantify economic risk, even if not the specific numbers.<ref>{{web cite|url=http://delong.typepad.com/sdj/2006/12/do_unto_others.html|title= Do unto others...|author=[[J. Bradford DeLong]]}}</ref><ref>{{web cite|url=http://johnquiggin.com/wp-content/uploads/2006/12/sternreviewed06121.pdf|title=Stern and the critics on discounting|author=[[John Quiggin]]}}</ref>

Preliminary studies suggest that costs and benefits of mitigating global warming are broadly comparable in magnitude.<ref>{{web cite | url=http://www.ft.com/cms/s/0/38c1bfa0-09bd-11dd-81bf-0000779fd2ac.html | title= Full quote from IPCC on costs of climate change| author=Terry Barker|date=April 14, 2008|accessdate=2008-04-14|publisher=FT.com}}</ref>

According to [[United Nations Environment Programme]] (UNEP), economic sectors likely to face difficulties related to climate change include [[bank]]s, [[Climate change and agriculture|agriculture]], transport and others.<ref>{{cite web | url=http://www.unepfi.org/fileadmin/documents/CEO_briefing_climate_change_2002_en.pdf | format= [[Portable Document Format|PDF]] | title = Climate Risk to Global Economy |last = Dlugolecki |first= Andrew |coauthors= ''et al.'' |work = CEO Briefing: UNEP FI Climate Change Working Group | publisher = [[United Nations Environment Programme]] |accessdate=2007-04-29 |year=2002}}</ref> Developing countries dependent upon agriculture will be particularly harmed by global warming.<ref>{{cite web | url= http://www.rff.org/Publications/Resources/Documents/164/RFF-Resources-164_Thomas%20Schelling.pdf | title = Thomas Schelling: Developing Countries Will Suffer Most from Global Warming| accessdate=2008-03-01 | work = Resources 164 |format=PDF}} </ref>

==Adaptation and mitigation==
{{main|Adaptation to global warming|Mitigation of global warming|Kyoto Protocol}}
The [[Scientific opinion on climate change|broad agreement]] among climate scientists that global temperatures will continue to increase has led some [[nation]]s, [[state]]s, [[corporation]]s and individuals to implement actions to try to curtail global warming or adjust to it. Many environmental groups encourage [[Individual and political action on climate change|individual action]] against global warming, often by the consumer, but also by community and regional organizations. Others have suggested a [[quota]] on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO2 emissions.<ref>{{cite web| title = Climate Control: a proposal for controlling global greenhouse gas emissions | publisher = Sustento Institute | url = http://sustento.org.nz/wp-content/uploads/2007/06/climate-control.pdf | format = [[Portable Document Format|PDF]] | accessdate = 2007-12-10}}</ref><ref>{{cite web | title = Rigged - The climate talks are a stitch-up, as no one is talking about supply. | first = George | last = Monbiot | url = http://www.monbiot.com/archives/2007/12/11/rigged/ | format = HTML | accessdate = 2007-12-22}}</ref>

There has also been [[business action on climate change]], including efforts at increased energy efficiency and limited moves towards use of [[alternative fuels]]. One recently developed concept is that of greenhouse gas [[emissions trading]] through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances.

The world's primary international agreement on combating global warming is the [[Kyoto Protocol]], an amendment to the [[United Nations Framework Convention on Climate Change|UNFCCC]] negotiated in 1997. The Protocol now covers more than 160 countries globally and over 55 percent of global greenhouse gas emissions.<ref>{{cite web | url=http://unfccc.int/files/essential_background/kyoto_protocol/application/pdf/kpstats.pdf | format=[[Portable Document Format|PDF]] |title=Kyoto Protocol Status of Ratification | publisher=[[United Nations Framework Convention on Climate Change]] | date=[[2006-07-10]] | accessdate=2007-04-27}}</ref> Only the [[United States]] and [[Kazakhstan]] have not ratified the treaty, with the United States historically being the world's [[greenhouse gas emissions by the United States|largest emitter]] of greenhouse gas. This treaty expires in 2012, and international talks began in May 2007 on a future treaty to succeed the current one.<ref>[http://www.boston.com/news/science/articles/2007/05/14/climate_talks_face_international_hurdles/ Climate talks face international hurdles], by Arthur Max, Associated press, 5/14/07.</ref> China and India, though exempt from its provisions as [[developing countries]], have ratified the Kyoto Protocol. China may have passed the U.S. in total annual greenhouse gas emissions according to some recent studies.<ref>{{cite web |url= http://www.berkeley.edu/news/media/releases/2008/03/10_chinaco2.shtml |title= New analysis finds alarming increase in expected growth of China CO2 emissions |accessdate=2008-03-10 |author=Sarah Yang, Media Relations |date=March 13, 2001|publisher= UC Berkeley }}</ref> Chinese Premier [[Wen Jiabao]] has called on the nation to redouble its efforts to tackle [[pollution]] and global warming.<ref>{{cite web|url=http://www.planetark.com/dailynewsstory.cfm/newsid/43027/story.htm|title=Wen Urges Greater China Effort to Fight Pollution, July 10, 2007, Reuters, via planetark.com|accessdate=2007-07-27}}</ref>

[[U.S. President]] [[George W. Bush]] contends that the Kyoto Protocol is an unfair and ineffective means of addressing global climate change concerns, claiming it that it "exempts 80 percent of the world, including major population centers such as [[China]] and [[India]], from compliance, and would cause serious harm to the U.S. economy."<ref>{{cite web |url=http://www.whitehouse.gov/news/releases/2001/03/20010314.html|title=Text of a Letter from the President to Senators Hagel, Helms, Craig, and Roberts |accessdate=2007-11-21 |author=[[George W. Bush]] |date=March 13, 2001|publisher=Office of the Press Secretary}}</ref> Bush has instead promoted improved energy technology as a means to combat climate change,<ref>[http://www.whitehouse.gov/stateoftheunion/2008/index.html State of the Union Address], retrieved 2008-01-28. "The United States is committed to strengthening our energy security and confronting global climate change. And the best way to meet these goals is for America to continue leading the way toward the development of cleaner and more energy-efficient technology."</ref> while various state and city governments within the United States have begun their own initiatives to indicate support and compliance with the Kyoto Protocol on a local basis, such as the [[Regional Greenhouse Gas Initiative]].<ref>{{cite web| url=http://www.rggi.org/ |title=Regional Greenhouse Gas Initiative| accessdate=2006-11-07}}</ref> The [[U.S. Climate Change Science Program]] is a joint program of over 20 U.S. federal agencies working together to investigate climate change.

The IPCC's Working Group III is responsible for crafting reports that deal with the mitigation of global warming and analyzing the costs and benefits of different approaches. In the 2007 [[IPCC Fourth Assessment Report]], they conclude that no one technology or sector can be completely responsible for mitigating future warming. They find there are key practices and technologies in various sectors, such as [[energy supply]], [[transport]]ation, [[industry]], and [[agriculture]], that should be implemented to reduced global emissions. They estimate that stabilization of [[carbon dioxide equivalent]] between 445 and 710 ppm by 2030 will result in between a 0.6 percent increase and three percent decrease in global [[gross domestic product]].<ref>{{cite web | url= http://arch.rivm.nl/env/int/ipcc/pages_media/FAR4docs/final_pdfs_ar4/SPM.pdf | format=[[Portable Document Format|PDF]] | title=Summary for Policymakers | work=Climate Change 2007: The Physical Science Basis. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2007-12-09 | date=[[2007-05-04]] | publisher=[[Intergovernmental Panel on Climate Change]]}}</ref>
According to Working Group III, to limit temperature rise to 2 degrees Celsius, "developed countries as a group would need to reduce their emissions to below 1990 levels in 2020 (on the order of –10 percent to 40 percent below 1990 levels for most of the considered regimes) and to still lower levels by 2050 (40 percent (Sic. 80 percent in Box 13.7, p776) to 95 percent below 1990 levels), even if developing countries make substantial reductions."<ref> {{cite web | url= http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-chapter13.pdf | format=[[Portable Document Format|PDF]] | title= Policies, Instruments and Co-operative Arrangements | work=Policies, Instruments and Co-operative Arrangements. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change | accessdate=2008-04-26 | date=[[2007-05-04]] | publisher=[[Intergovernmental Panel on Climate Change]] | last=Guptal | first=Sujata | coauthors=''et al.'' | pages=21 | quote=..developed countries as a group would need to reduce their emissions to below 1990 levels in 2020 (on the order of –10% to 40% below 1990 levels for most of the considered regimes) and to still lower levels by 2050 (40% to 95% below 1990 levels), even if developing countries make substantial reductions.}} </ref>

==Economic and political debate==
{{main|Global warming controversy|Politics of global warming|Economics of global warming}}
{{see also|Climate change denial|List of countries by greenhouse gas emissions per capita|List of countries by carbon dioxide emissions per capita|List of countries by carbon dioxide emissions|List of countries by ratio of GDP to carbon dioxide emissions}}
{{Double image stack|right|GHG per capita 2000.svg|GHG by country 2000.svg|250|Per capita greenhouse gas emissions in 2000, including [[Land use, land-use change and forestry|land-use change]].|Per country greenhouse gas emissions in 2000, including land-use change.}}
Increased publicity of the scientific findings surrounding global warming has resulted in political and economic debate.<ref>{{Citation | first=Spencer | last=Weart | author-link=Spencer R. Weart | contribution=The Public and Climate Change | contribution-url=http://www.aip.org/history/climate/Public.htm | title=The Discovery of Global Warming | editor-first=Spencer | editor-last=Weart | editor-link=Spencer R. Weart | url=http://www.aip.org/history/climate/index.html | publisher=[[American Institute of Physics]] | year=2006 | access-date=2007-04-14 }}</ref> Poor regions, particularly [[Africa]], appear at greatest risk from the projected effects of global warming, while their emissions have been small compared to the developed world.<ref>{{cite news | title= Poor Nations to Bear Brunt as World Warms | first=Andrew | last=Revkin | date=[[2007-04-01]] | publisher=[[The New York Times]] | url= http://www.nytimes.com/2007/04/01/science/earth/01climate.html?ex=1333080000&en=6c687d64add0b7ba&ei=5088&partner=rssnyt&emc=rss| accessdate = 2007-05-02}}</ref> At the same time, [[developing country]] exemptions from provisions of the [[Kyoto Protocol]] have been criticized by the [[United States]] and [[Australia]], and used as part of a rationale for continued non-ratification by the U.S.<ref>{{cite web | title= China's emissions may surpass the US in 2007 | first=Catherine | last=Brahic | date=[[2006-04-25]] | publisher=[[New Scientist]] | url=http://environment.newscientist.com/article/dn11707-chinas-emissions-to-surpass-the-us-within-months.html | accessdate = 2007-05-02}}</ref>In the [[Western world]], the idea of human influence on climate has gained wider public acceptance in [[Europe]] than in the United States.<ref>{{cite news | title=More in Europe worry about climate than in U.S., poll shows | first=Thomas | last=Crampton | date=[[2007-01-04]] | publisher=[[International Herald Tribune]] | url=http://www.iht.com/articles/2007/01/04/news/poll.php | accessdate = 2007-04-14}}</ref><ref>{{cite web | title = Summary of Findings | work = Little Consensus on Global Warming. Partisanship Drives Opinion | publisher = [[Pew Research Center]] | date = [[2006-07-12]] | accessdate = 2007-04-14 | url = http://people-press.org/reports/display.php3?ReportID=280}}</ref>

The issue of climate change has sparked debate weighing the benefits of limiting [[industrial process|industrial]] [[Air pollution|emissions]] of [[greenhouse gas]]es against the [[Economics of global warming|costs]] that such changes would entail. There has been discussion in several countries about the cost and benefits of adopting [[Alternative energy|alternative energy sources]] in order to reduce carbon emissions.<ref>{{cite news |url= http://news.bbc.co.uk/2/hi/europe/6432829.stm |title= EU agrees on carbon dioxide cuts |date= [[2007-03-09]] |publisher= [[BBC]] |accessdate=2007-05-04}}</ref> Organizations and companies such as the [[Competitive Enterprise Institute]] and [[ExxonMobil]] have emphasized more conservative climate change scenarios while highlighting the potential economic cost of stricter controls.<ref>{{cite news |last=Begley |first=Sharon |title=The Truth About Denial|publisher=Newsweek |date=2007-08-13 |url=http://www.newsweek.com/id/32482 |accessdate=2007-08-13}}</ref><ref>{{cite web | title=Royal Society tells Exxon: stop funding climate change denial | url=http://www.guardian.co.uk/environment/2006/sep/20/oilandpetrol.business | first=David | last=Adams | publisher=[[The Guardian]] | date=[[2006-09-20]] | accessdate=2007-08-09}}</ref><ref name="MSNBC 01-12">{{cite news |title= Exxon cuts ties to global warming skeptics |url= http://www.msnbc.msn.com/id/16593606 |publisher= [[MSNBC]] |date= [[2007-01-12]] |accessdate= 2007-05-02}}</ref><ref>{{cite news |title= Report: Big Money Confusing Public on Global Warming |url= http://abcnews.go.com/Technology/Business/story?id=2767979&page=1 |last= Sandell |first= Clayton |publisher= [[American Broadcasting Company|ABC]] |date= [[2007-01-03]] |accessdate= 2007-04-27}}</ref> Likewise, various environmental lobbies and a number of public figures have launched campaigns to emphasize the potential [[Effects of global warming|risks of climate change]] and promote the implementation of stricter controls. Some fossil fuel companies have scaled back their efforts in recent years,<ref> {{cite news | url=http://www.usatoday.com/weather/climate/globalwarming/2007-05-18-greenpeace-exxon_N.htm |title= Greenpeace: Exxon still funding climate skeptics |date=[[2007-05-18]] |publisher= [[USA Today]] |accessdate=2007-07-09}}</ref> or called for policies to reduce global warming.<ref>{{cite press release|url=http://www.ceres.org/news/news_item.php?nid=56|title=Global Warming Resolutions at U.S. Oil Companies Bring Policy Commitments from Leaders, and Record High Votes at Laggards|date=April 28, 2004| publisher=Ceres|accessdate=2007-07-27}}</ref>

Another point of contention is the degree to which [[Newly industrialized country|emerging economies]] such as [[India]] and [[China]] should be expected to constrain their emissions. According to recent reports, China's [[List of countries by carbon dioxide emissions|gross national CO2 emissions]] may now exceed those of the U.S.<ref>{{cite news| url=http://news.bbc.co.uk/2/hi/asia-pacific/7347638.stm|title= China now top carbon polluter| publisher= [[BBC News]] | date= [[2008-04-14]] | accessdate=2008-04-22}}</ref><ref>{{cite news| url=http://news.theage.com.au/china-is-biggest-co2-emitter-research/20080415-26an.html|title= China is biggest CO2 emitter : research| publisher= [[The Age]] | date= [[2008-04-15]] | accessdate=2008-04-22}}</ref><ref>{{cite news| url=http://www.usatoday.com/tech/science/2007-06-20-124188869_x.htm| title= Group: China tops world in CO2 emissions| publisher=[[Associated Press]] | date=[[2007-06-20]] | accessdate=2007-10-16}}</ref><ref>{{cite news| url=http://www.livemint.com/2007/06/20235536/China-surpassed-US-in-carbon-e.html| title= Group: China surpassed US in carbon emissions in 2006: Dutch report| publisher=[[Reuters]] | date=[[2007-06-20]] | accessdate=2007-10-16}}</ref> China has contended that it has less of an obligation to reduce emissions since its [[List of countries by carbon dioxide emissions per capita|per capita emissions]] are roughly one-fifth that of the United States.<ref>[http://www.newsvine.com/_news/2007/12/07/1147788-china-says-west-should-deal-with-warming China: US should take lead on climate], by Michael Casey, Associated Press, via newsvine.com 12/7/07. </ref> India, also exempt from Kyoto restrictions and another of the biggest sources of industrial emissions, has made similar assertions.<ref>[http://www.oregonlive.com/science/oregonian/index.ssf?/base/science/1184718333231440.xml&coll=7 India's glaciers give grim message on warming], by Somni Sengupta, 7/17/07, New York Times via oregonlive.com.</ref> The U.S. contends that if they must bear the cost of reducing emissions, then China should do the same.<ref> [http://news.bbc.co.uk/2/hi/science/nature/6610653.stm Chinese object to climate draft], BBC, 5/1/07; [http://www.washingtonpost.com/wp-dyn/content/article/2007/06/05/AR2007060502546_2.html?hpid=topnews In Battle for U.S. Carbon Caps, Eyes and Efforts Focus on China],by Steven Mufson, Washington Post, 6/6/07.</ref>

==Related climatic issues==
{{main|Ocean acidification|global dimming|ozone depletion}}
A variety of issues are often raised in relation to global warming. One is [[ocean acidification]]. Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans.<ref>{{cite web |url=http://science.hq.nasa.gov/oceans/system/carbon.html |title=The Ocean and the Carbon Cycle |accessdate=2007-03-04 |date=[[2005-06-21]] |work=[[NASA]]}}</ref>CO2 dissolved in the ocean reacts with water to form [[carbonic acid]], resulting in acidification. Ocean surface [[pH]] is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004,<ref>{{cite journal |last= Jacobson |first= Mark Z. |date= [[2005-04-02]] |title= Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry |journal= [[Journal of Geophysical Research]] |volume= 110 |issue= D7 |id= D07302 |url= http://www.stanford.edu/group/efmh/jacobson/2004JD005220.pdf |format=[[Portable Document Format|PDF]] |doi = 10.1029/2004JD005220 |accessdate=2007-04-28 |pages= D07302}}</ref>and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO2.<ref name="grida7" /><ref>{{cite journal| last = Caldeira | first = Ken | coauthors= Wickett, Michael E. | title = Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean | journal = [[Journal of Geophysical Research]] |volume = 110 |issue = C09S04 | doi=10.1029/2004JC002671 | pages = 1–12 | url = http://www.agu.org/pubs/crossref/2005/2004JC002671.shtml | date = [[2005-09-21]] | accessdate = 2006-02-14}}</ref> Since organisms and ecosystems are adapted to a narrow range of pH, this raises [[extinction]] concerns, directly driven by increased atmospheric CO2, that could disrupt [[food chain#Food web|food webs]] and impact human societies that depend on marine ecosystem services.<ref>{{cite paper |author=Raven, John A.; ''et al.'' |title= Ocean acidification due to increasing atmospheric carbon dioxide |publisher= [[Royal Society]] |date= [[2005-06-30]] |url= http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13314 |format= [[Active Server Pages|ASP]] |accessdate= 2007-05-04}}</ref>

[[Global dimming]], the gradual reduction in the amount of global direct [[irradiance]] at the Earth's surface, may have partially mitigated global warming in the late 20th century. From 1960 to 1990 human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of the global warming, and that greenhouse gases would have resulted in more warming than observed if not for these dimming agents.<ref name="grida7" />

[[Ozone depletion]], the steady decline in the total amount of [[ozone]] in Earth's [[stratosphere]], is frequently cited in relation to global warming. Although there are [[Ozone depletion#Ozone depletion and global warming|areas of linkage]], the relationship between the two is not strong.

==See also==

* [[Glossary of climate change]]
* [[List of climate change topics]]

==Notes and references==
{{reflist|colwidth=25em}}

==Further reading==
{{Wikinewscat|Climate change}}
{{Wikibooks|Climate Change}}
{{wikiversity|Topic:Climate change}}
{{Portal|Environment}}
{{EnergyPortal}}
{{refbegin}}
* {{cite book
| title = Financial Risks of Climate Change
| author = Association of British Insurers
| year= 2005-06
| url=http://www.abi.org.uk/Display/File/Child/552/Financial_Risks_of_Climate_Change.pdf
| format = [[Portable Document Format|PDF]]
}}
* {{cite journal
| last = Barnett | first = Tim P.
| coauthors = J. C. Adam, D. P. Lettenmaier
| date = [[2005-11-17]]
| title = Potential impacts of a warming climate on water availability in snow-dominated regions
| journal = [[Nature (journal)|Nature]]
| volume = 438 | issue = 7066 | pages = 303–309
| url = http://www.nature.com/nature/journal/v438/n7066/abs/nature04141.html
| doi = 10.1038/nature04141
| format = abstract
}}
* {{cite journal
| last= Behrenfeld | first= Michael J.
| coauthors = Robert T. O'Malley, David A. Siegel, Charles R. McClain, Jorge L. Sarmiento, Gene C. Feldman, Allen G. Milligan, Paul G. Falkowski, Ricardo M. Letelier, Emanuel S. Boss
| date = [[2006-12-07]]
| title = Climate-driven trends in contemporary ocean productivity
| journal = [[Nature (journal)|Nature]]
| volume = 444 | issue = 7120 | pages = 752–755
| url=http://www.icess.ucsb.edu/~davey/MyPapers/Behrenfeld_etal_2006_Nature.pdf
| format = [[Portable Document Format|PDF]]
| doi=10.1038/nature05317
}}
* {{cite journal
| first = Onelack | last= Choi
| coauthors = Ann Fisher
| month = May | year = 2005
| title = The Impacts of Socioeconomic Development and Climate Change on Severe Weather Catastrophe Losses: Mid-Atlantic Region (MAR) and the U.S.
| journal = Climate Change
| volume = 58 | issue = 1–2 | pages = 149–170
| doi = 10.1023/A:1023459216609
| url = http://www.springerlink.com/content/m6308777613702q0/
}}
* {{cite book
| last = Dyurgerov | first = Mark B.
| coauthors = Mark F. Meier
| year = 2005
| title = Glaciers and the Changing Earth System: a 2004 Snapshot
| publisher = Institute of Arctic and Alpine Research Occasional Paper #58
| url = http://instaar.colorado.edu/other/download/OP58_dyurgerov_meier.pdf
| format = [[Portable Document Format|PDF]]
| id = {{ISSN|0069-6145}}
}}
* {{cite journal
| last=Emanuel | first=Kerry A.
| authorlink=Kerry Emanuel
| date= [[2005-08-04]]
| title=Increasing destructiveness of tropical cyclones over the past 30 years.
| journal= [[Nature (journal)|Nature]]
| volume=436 | issue=7051 | pages=686–688
| url=ftp://texmex.mit.edu/pub/emanuel/PAPERS/NATURE03906.pdf
| format = [[Portable Document Format|PDF]]
| doi=10.1038/nature03906
}}
* {{cite journal
| last=Hansen | first=James
| authorlink=James Hansen
| coauthors=Larissa Nazarenko, Reto Ruedy, Makiko Sato, Josh Willis, Anthony Del Genio, Dorothy Koch, Andrew Lacis, Ken Lo, Surabi Menon, Tica Novakov, Judith Perlwitz, Gary Russell, [[Gavin A. Schmidt]], Nicholas Tausnev
| date= [[2005-06-03]]
| title=Earth's Energy Imbalance: Confirmation and Implications
| journal=[[Science (journal)|Science]]
| volume=308 | issue=5727 | pages=1431–1435
| url=http://pangea.stanford.edu/research/Oceans/GES205/Hansen_Science_Earth's%20Energy%20Balance.pdf
| format = [[Portable Document Format|PDF]]
| doi=10.1126/science.1110252
| pmid=15860591
}}
* {{cite journal
| last= Hinrichs | first= Kai-Uwe
| coauthors=Laura R. Hmelo, Sean P. Sylva
| date=[[2003-02-21]]
| title = Molecular Fossil Record of Elevated Methane Levels in Late Pleistocene Coastal Waters
| journal = [[Science (journal)|Science]]
| volume = 299
| issue = 5610
| pages = 1214–1217
| doi= 10.1126/science.1079601
| pmid = 12595688
}}
* {{cite news
| last=Hirsch | first=Tim
| publisher=[[BBC]]
| url=http://news.bbc.co.uk/2/hi/science/nature/4604332.stm
| title=Plants revealed as methane source
| date=[[2006-01-11]]
}}
* {{cite journal
| last = Hoyt | first = Douglas V.
| coauthors = Kenneth H. Schatten
| year = 1993–11
| title = A discussion of plausible solar irradiance variations, 1700–1992
| journal = [[Journal of Geophysical Research]]
| volume = 98 | issue = A11 | pages = 18,895–18,906
| url = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993JGR....9818895H&db_key=AST&data_type=HTML&format=&high=448f267ff303582
}}
* {{cite journal
| author = A. V. Karnaukhov
| year = 2001
| title = Role of the Biosphere in the Formation of the Earth’s Climate: The Greenhouse Catastrophe
| journal = Biophysics
| volume = 46 | issue = 6
| url = http://avturchin.narod.ru/Green.pdf
| format = [[Portable Document Format|PDF]]
}}
* {{cite book
| last = Kenneth | first = James P.
| coauthors = Kevin G. Cannariato, Ingrid L. Hendy, Richard J. Behl
| year = [[2003-02-14]]
| title = Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis
| publisher = [[American Geophysical Union]]
| url = https://www.agu.org/cgi-bin/agubooks?book=ASSP0542960
}}
* {{cite news
| last = Keppler | first = Frank
| coauthors = Marc Brass, Jack Hamilton, Thomas Röckmann
| title = Global Warming - The Blame Is not with the Plants
| url = http://www.mpg.de/english/illustrationsDocumentation/documentation/pressReleases/2006/pressRelease200601131/index.html
| publisher = [[Max Planck Society]]
| date = [[2006-01-18]]
}}
* {{cite journal
| title = The effect of increasing solar activity on the Sun's total and open magnetic flux during multiple cycles: Implications for solar forcing of climate
| last = Lean | first = Judith L.
| coauthors = Y.M. Wang, N.R. Sheeley
| year = 2002–12
| journal = [[Geophysical Research Letters]]
| volume = 29 | issue = 24
| url = http://adsabs.harvard.edu/abs/2002GeoRL..29x..77L
| doi = 10.1029/2002GL015880
| pages = 2224
| format = abstract
}}
* {{cite book
| last = Lerner | first = K. Lee
| coauthors = Brenda Wilmoth Lerner
| title = Environmental issues : essential primary sources.
| publisher = [[Thomson Gale]]
| date = [[2006-07-26]]
| isbn = 1414406258
}}
* {{cite journal
| last = McLaughlin | first = Joseph B.
| coauthors = Angelo DePaola, Cheryl A. Bopp, Karen A. Martinek, Nancy P. Napolilli, Christine G. Allison, Shelley L. Murray, Eric C. Thompson, Michele M. Bird, John P. Middaugh
| title = Outbreak of Vibrio parahaemolyticus gastroenteritis associated with Alaskan oysters
| journal = [[New England Journal of Medicine]]
| volume = 353 | issue = 14 | pages = 1463–1470
| publisher = New England Medical Society
| date = [[2005-10-06]]
| url = http://content.nejm.org/cgi/content/abstract/353/14/1463
| doi = 10.1056/NEJMoa051594
| format = abstract
| pmid = 16207848
}}''(online version requires registration)''
* {{cite journal
| last = Muscheler, Raimund
| coauthors = Fortunat Joos, Simon A. Müller, Ian Snowball
| date = [[2005-07-28]]
| title = Climate: How unusual is today's solar activity?
| journal = [[Nature (journal)|Nature]]
| volume = 436 | issue = 7012 | pages = 1084–1087
| url = http://www.cgd.ucar.edu/ccr/raimund/publications/Muscheler_et_al_Nature2005.pdf
| format = [[Portable Document Format|PDF]]
| doi = 10.1038/nature04045
}}
* {{cite journal
| last = Oerlemans | first = J.
| date = [[2005-04-29]]
| title = Extracting a Climate Signal from 169 Glacier Records
| journal = [[Science (journal)|Science]]
| volume = 308 | issue = 5722 | pages = 675–677
| url=http://www.cosis.net/abstracts/EGU05/04572/EGU05-J-04572.pdf
| format = [[Portable Document Format|PDF]]
| doi = 10.1126/science.1107046
| pmid = 15746388
}}
* {{cite journal
| last = Oreskes | first = Naomi
| authorlink=Naomi Oreskes
| date = [[2004-12-03]]
| title = Beyond the Ivory Tower: The Scientific Consensus on Climate Change
| journal = [[Science (journal)|Science]]
| volume = 306 | issue = 5702 | pages = 1686
| url = http://www.sciencemag.org/cgi/reprint/306/5702/1686.pdf
| format = [[Portable Document Format|PDF]]
| doi = 10.1126/science.1103618
}}
* {{cite journal
| last = Purse | first = Bethan V.
| coauthors = Philip S. Mellor, David J. Rogers, Alan R. Samuel, Peter P. C. Mertens, Matthew Baylis
| title = Climate change and the recent emergence of bluetongue in Europe
| journal = [[Nature Reviews Microbiology]]
| volume = 3 | issue = 2 | pages = 171–181
| month = February | year = 2005
| doi = 10.1038/nrmicro1090
| url=http://www.nature.com/nrmicro/journal/v3/n2/abs/nrmicro1090_fs.html
| format = abstract
}}
* {{cite news
| last = Revkin | first = Andrew C
| date = [[2005-11-05]]
| title = Rise in Gases Unmatched by a History in Ancient Ice
| publisher = [[The New York Times]]
| url = http://www.nytimes.com/2005/11/25/science/earth/25core.html?ei=5090&en=d5078e33050b2b0c&ex=1290574800&adxnnl=1&partner=rssuserland&emc=rss
}}
* {{cite book
| last = Ruddiman | first = William F.
| authorlink=William Ruddiman
| date = [[2005-12-15]]
| title = Earth's Climate Past and Future
| location = New York
| publisher = [[Princeton University Press]]
| isbn = 0-7167-3741-8
| url = http://www.whfreeman.com/ruddiman/
}}
* {{cite book
| last = Ruddiman | first = William F.
| authorlink=William Ruddiman
| date = [[2005-08-01]]
| title = Plows, Plagues, and Petroleum: How Humans Took Control of Climate
| location = New Jersey
| publisher = [[Princeton University Press]]
| isbn = 0-691-12164-8
}}
* {{cite journal
| last = Solanki | first = Sami K.
| authorlink=Sami Solanki
| coauthors = I.G. Usoskin, B. Kromer, M. Schussler, J. Beer
| date = [[2004-10-23]]
| title = Unusual activity of the Sun during recent decades compared to the previous 11,000 years.
| journal = [[Nature (journal)|Nature]]
| volume = 431 | pages = 1084–1087
| url = http://cc.oulu.fi/%7Eusoskin/personal/nature02995.pdf
| format = [[Portable Document Format|PDF]]
| doi = 10.1038/nature02995
}}
* {{cite journal
| last = Solanki | first = Sami K.
| authorlink=Sami Solanki
| coauthors = I. G. Usoskin, B. Kromer, M. Schüssler, J. Beer
| date = [[2005-07-28]]
| title = Climate: How unusual is today's solar activity? (Reply)
| journal = [[Nature (journal)|Nature]]
| volume = 436
| pages = E4–E5
| url = http://cc.oulu.fi/%7Eusoskin/personal/sola_nature05.pdf
| format = [[Portable Document Format|PDF]]
| doi = 10.1038/nature04046
}}
* {{cite journal
| last = Sowers | first = Todd
| date = [[2006-02-10]]
| journal = Science
| volume = 311 | issue = 5762 | pages = 838–840
| title = Late Quaternary Atmospheric CH4 Isotope Record Suggests Marine Clathrates Are Stable
| doi = 10.1126/science.1121235
| pmid = 16469923
}}
* {{cite journal
| last = Svensmark | first = Henrik
| authorlink=Henrik Svensmark
| coauthors = Jens Olaf P. Pedersen, Nigel D. Marsh, Martin B. Enghoff, Ulrik I. Uuggerhøj
| year = [[2007-02-08]]
| title = Experimental evidence for the role of ions in particle nucleation under atmospheric conditions
| journal = [[Proceedings of the Royal Society]] A
| volume = 463 | issue = 2078 | pages = 385–396
| publisher = FirstCite Early Online Publishing
| doi = 10.1098/rspa.2006.1773
}}''(online version requires registration)''
* {{cite journal
| last = Walter | first = K. M.
| coauthors = S. A. Zimov, Jeff P. Chanton, D. Verbyla, [[F. Stuart Chapin III|F. S. Chapin]]
| date = [[2006-09-07]]
| title = Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming
| journal = [[Nature (journal)|Nature]]
| volume = 443 | issue = 7107 | pages = 71–75
| doi = 10.1038/nature05040
}}
* {{cite journal
| last = Wang | first = Y.-M.
| coauthors = J.L. Lean, N.R. Sheeley
| date = [[2005-05-20]]
| title = Modeling the sun's magnetic field and irradiance since 1713
| journal = [[Astrophysical Journal]]
| volume = 625 | pages = 522–538
| url = http://climatesci.colorado.edu/publications/pdf/Wang_2005.pdf
| format = [[Portable Document Format|PDF]]
| doi = 10.1086/429689
}}
{{refend}}

==External links==
{{refbegin}}
; Scientific
* [http://www.ipcc.ch Intergovernmental Panel on Climate Change] and [http://www.planetark.com/dailynewsstory.cfm/newsid/44456/story.htm UN Climate Panel Report's Key Findings].
* [http://www.nature.com/climate/index.html Nature Reports Climate Change]
* [http://www.metoffice.gov.uk/research/hadleycentre/index.html The UK Met Office Hadley Centre site]
* [http://www.ncdc.noaa.gov/oa/climate/globalwarming.html#INTRO NOAA's Global Warming FAQ]
* [http://www.aip.org/history/climate Discovery of Global Warming] – An extensive introduction to the topic and the history of its discovery, written by [[Spencer R. Weart]]
* [http://news.bbc.co.uk/1/hi/world/6460635.stm Caution urged on climate 'risks']
* [http://www.virtualcentre.org/en/library/key_pub/longshad/A0701E00.htm Impact of Livestock on Global Warming (UN Report)]

; Educational
* [http://climate.jpl.nasa.gov/ Global Climate Change: NASA's Eyes on the Earth] - Climate change overviews, key indicators, multimedia and current news.
* [http://green.nationalgeographic.com/environment/global-warming/gw-overview.html What Is Global Warming?] – Shockwave presentation from [[National Geographic]]
* [http://edgcm.columbia.edu/ The EdGCM (Educational Global Climate Modelling) Project] – A free research-quality simulation for students, educators, and scientists alike, with a user-friendly interface that runs on desktop computers
* [http://discover.itsc.uah.edu/ DISCOVER] Satellite-based ocean and climate data since 1979 from [[NASA]]
* [http://www.pewclimate.org/ The Pew Center on global climate change]
* [http://www.globalwarmingart.com/ Global Warming Art]
* [http://osulibrary.oregonstate.edu/specialcollections/events/2007paulingconference/video-s3-4-washington.html Video] of a talk by [[Warren Washington]] titled "The Evolution of Global Warming Science: From Ideas to Scientific Facts"
* [http://demonstrations.wolfram.com/BestEffortGlobalWarmingTrajectories/ Best Effort Global Warming Trajectories] by Harvey Lam (Princeton University), [[The Wolfram Demonstrations Project]].

; Other
* [http://www.istl.org/01-fall/internet.html Science and Technology Sources on the Internet] – Extensive commented list of Internet resources
* [http://www.ucsusa.org/global_warming/ Union of Concerned Scientists Global Warming page]
* [http://www.abc.net.au/catalyst/stories/s1647466.htm Watch and read 'Tipping Point'], Australian science documentary about effects of global warming on rare, common, and endangered wildlife
* [http://www.un.org/climatechange Gateway to the UN System's Work on Climate Change]
{{refend}}

{{Global warming|state=expanded}}

[[Category:Global warming| ]]
[[Category:Carbon finance]]
[[Category:Climate change feedbacks and causes]]
[[Category:Economic problems]]
[[Category:History of climate]]
[[Category:Climate change]]
[[Category:Anthropocene]]

{{Link FA|id}}
{{Link FA|de}}
{{Link FA|he}}
{{Link FA|hu}}
{{Link FA|fi}}
{{Link FA|th}}
[[af:Aardverwarming]]
[[ang:Woruldlicu wearmung]]
[[ar:احترار عالمي]]
[[zh-min-nan:Choân-kiû sio-lo̍h-hoà]]
[[bs:Globalno zatopljenje]]
[[bg:Глобално затопляне]]
[[ca:Escalfament global]]
[[ceb:Kalibotanong pagpanginit]]
[[cs:Globální oteplování]]
[[cy:Newid hinsawdd]]
[[da:Global opvarmning]]
[[de:Globale Erwärmung]]
[[et:Globaalne soojenemine]]
[[el:Παγκόσμια θέρμανση]]
[[es:Calentamiento global]]
[[eo:Tutmonda varmiĝo]]
[[eu:Berotze globala]]
[[fa:گرمایش زمین]]
[[fr:Réchauffement climatique]]
[[fur:Riscjaldament globâl]]
[[gd:Blàthachadh na cruinne]]
[[gl:Quentamento global]]
[[zh-classical:全球暖化]]
[[ko:지구 온난화]]
[[hy:Գլոբալ տաքացում]]
[[hi:भूमंडलीय ऊष्मीकरण]]
[[hr:Globalno zatopljenje]]
[[id:Pemanasan global]]
[[is:Heimshlýnun]]
[[it:Riscaldamento globale]]
[[he:התחממות עולמית]]
[[jv:Pamanasan global]]
[[ka:გლობალური დათბობა]]
[[lv:Globālā sasilšana]]
[[lt:Visuotinis atšilimas]]
[[hu:Globális felmelegedés]]
[[mk:Глобално затоплување]]
[[ml:ആഗോളതാപനം]]
[[mr:जागतिक तापमानवाढ]]
[[mn:Дэлхийн дулаарал]]
[[nl:Opwarming van de Aarde]]
[[ja:地球温暖化]]
[[no:Global oppvarming]]
[[nn:Global oppvarming]]
[[oc:Escalfament global]]
[[pl:Globalne ocieplenie]]
[[pt:Aquecimento global]]
[[ro:Încălzirea globală]]
[[ru:Глобальное потепление]]
[[si:පෘථිවිය උණුසුම් වීම]]
[[simple:Global warming]]
[[sk:Globálne otepľovanie]]
[[sl:Globalno segrevanje]]
[[sr:Глобално загревање]]
[[sh:Globalno zatopljenje]]
[[su:Jagat nyongkab]]
[[fi:Ilmaston lämpeneminen]]
[[sv:Global uppvärmning]]
[[ta:புவி சூடாதல்]]
[[th:ปรากฏการณ์โลกร้อน]]
[[vi:Sự nóng lên của khí hậu toàn cầu]]
[[tr:Küresel ısınma]]
[[uk:Глобальне потепління]]
[[wuu:全球暖化]]
[[yi:גלאבאלע אנווארימונג]]
[[zh-yue:全球變暖]]
[[bat-smg:Gluobalėnis atšėlėms]]
[[zh:全球变暖]]

Christianity

2008-10-22T22:41:35Z

ReaganFan0101:

{{Christianity}}
'''Christianity''' ([[Greek]] Χριστιανισμός, from the word Xριστός ([[Christ]]) is a [[Monotheistic religion #Christian view|monotheistic]] [[religion]]<ref name="Monotheism">Christianity's status as monotheistic is affirmed in, amongst other sources, the ''[[Catholic Encyclopedia]]'' (article "[http://www.newadvent.org/cathen/10499a.htm Monotheism]"); [[William F. Albright]], ''From the Stone Age to Christianity''; [[H. Richard Niebuhr]]; About.com, [http://ancienthistory.about.com/od/monotheisticreligions/ ''Monotheistic Religion resources'']; Kirsch, ''God Against the Gods''; Woodhead, ''An Introduction to Christianity''; [[Columbia Encyclopedia|The Columbia Electronic Encyclopedia]] [http://www.infoplease.com/ce6/society/A0833762.html ''Monotheism'']; The New Dictionary of [[Cultural literacy|Cultural Literacy]], [http://www.bartleby.com/59/5/monotheism.html ''monotheism'']; New Dictionary of Theology, [http://www.ntwrightpage.com/Wright_NDCT_Paul.htm ''Paul''], p. 496-499; Meconi. "Pagan Monotheism in Late Antiquity". p. 111f.</ref> centered on the life and teachings of [[Jesus]] as [[New Testament view on Jesus' life|presented in the New Testament]].<ref>[[BBC]], [http://www.bbc.co.uk/religion/religions/christianity/ ''BBC - Religion & Ethics - 566, Christianity'']</ref>

Its followers, known as [[Christian]]s,<ref name="name">The term "Christian" ([[Greek language|Greek]] {{polytonic|''Χριστιανός''}}) was first used in reference to Jesus's [[disciple (Christianity)|disciples]] in the city of [[Antioch]] {{bibleref|Acts|11:26|NASB}} about 44 AD, meaning "followers of Christ". The earliest recorded use of the term "Christianity" (Greek {{polytonic|''Χριστιανισμός''}}) was by [[Ignatius of Antioch]], around 100 AD. See Elwell/Comfort. ''Tyndale Bible Dictionary'', p. 266, 828</ref> believe that Jesus is the begotten<ref>The specification of Jesus as 'begotten' son is used to indicate the belief that Jesus is the Son of God by nature, as part of the Trinity, rather than by adoption, as Christians believe all true believers are. See ''Voting About God in Early Church Councils'' by [[Ramsay MacMullen]], Yale University Press, 2006</ref><ref> See: [[Arianism]]</ref> [[Son of God]] and the [[Messiah]] ([[Christ]]) [[Bible prophecy|prophesied]] in the [[Hebrew Bible]] (the part of [[scripture]] common to Christianity and [[Judaism]]). To Christians, Jesus Christ is a teacher, the [[role model|model]] of a [[virtue|virtuous]] life, the [[revelation|revealer]] of [[God in Christianity|God]], and most importantly the [[salvation|saviour]] of humanity who suffered, died, and was [[resurrection|resurrected]] to bring about salvation from [[Sin#Christian views of sin|sin]].<ref name="McGrath4">McGrath, ''Christianity: An Introduction'', p. 4-6.</ref> Christians maintain that Jesus [[Ascension of Jesus|ascended]] into [[heaven]], and most [[Christian denomination|denominations]] teach that Jesus will [[Second Coming|return]] to [[Last judgement|judge]] the living and the dead, granting [[Immortality|everlasting life]] to his followers. Christians call the message of Jesus Christ [[Good news (Christianity)|the Gospel]] ("good news") and hence label the written accounts of his ministry as [[gospel]]s.

Like [[Judaism]] and [[Islam]], Christianity is classified as an [[Abrahamic religion]] (''see also [[Judeo-Christian]]'').<ref name="J.Smith98">J.Z.Smith, p. 276.</ref><ref name="Anidjar2001">Anidjar, p. 3.</ref><ref>Fowler, ''World Religions: An Introduction for Students'', p. 131.</ref> [[Jewish Christianity#Jewish origin of Christianity|Christianity began as a Jewish sect]]<ref name="Robinson">Robinson, ''Essential Judaism: A Complete Guide to Beliefs, Customs and Rituals'', p. 229.</ref><ref name="Esler">Esler. ''The Early Christian World''. p. 157f.</ref> in the eastern [[History of the Mediterranean region|Mediterranean]], quickly grew in size and influence over a few decades, and by the 4th century had become the dominant religion within the [[Roman Empire]]. During the [[Middle Ages]], most of the remainder of [[Europe]] was [[Christianization|Christianized]], with Christians also being a (sometimes large) religious minority in the [[Middle East]], [[North Africa]], and parts of [[Thomas Christians|India]].<ref>McManners, ''Oxford Illustrated History of Christianity'', p. 301-303.</ref> Following the [[Age of Discovery]], through [[Missionary|missionary work]] and colonization, Christianity spread to the [[Americas]] and the rest of the world.

Christianity has played a prominent role in the [[history of Western civilization|shaping of Western civilization]] at least since the 4th century.<ref name="Orlandis"/> As of the early 21st century, Christianity has between 1.5 billion<ref>"between 1,250 and 1,750 million adherents, depending on the criteria employed" (McGrath, ''Christianity: An Introduction'', page xvl.)</ref><ref>"1.5 thousand million Christians" (Hinnells, ''The Routledge Companion to the Study of Religion'', p. 441.)</ref> and 2.1 billion adherents,<ref>[http://www.adherents.com/Religions_By_Adherents.html Major Religions Ranked by Size]</ref> representing about a quarter to a third of the world's population.<ref>Hinnells, ''The Routledge Companion to the Study of Religion'', p. 441.</ref>

==Beliefs==
[[Image:Bloch-SermonOnTheMount.jpg|thumb|250px|right|The [[Sermon On the Mount]] by [[Carl Heinrich Bloch]], Danish painter, d. 1890.]]
In spite of important differences of interpretation and opinion, Christians share a set of beliefs that they hold as essential to their faith.<ref name="Olsen">Olson, ''The Mosaic of Christian Belief''.</ref>

=== Creeds ===
{{main|Creeds}}

Creeds (from Latin ''credo'' meaning "I believe") are concise doctrinal statements or confessions, usually of religious beliefs. They began as baptismal formulas and were later expanded during the [[Christology|Christological]] controversies of the [[4th century|fourth]] and [[5th century|fifth centuries]] to become statements of faith.

{{wikisource|Apostles Creed}}
The [[Apostles Creed]] (''Symbolum Apostolorum'') was developed between the second and ninth centuries. It is the most popular creed used in worship by Western Christians. Its central doctrines are those of the Trinity and God the Creator. Each of the doctrines found in this creed can be traced to statements current in the [[Apostolic Age|apostolic period]]. The creed was apparently used as a summary of Christian doctrine for baptismal candidates in the churches of Rome.<ref>Pelikan/Hotchkiss, ''Creeds and Confessions of Faith in the Christian Tradition''.</ref>
Since the Apostles Creed is still unaffected by the later Christological divisions, its statement of the articles of Christian faith remain largely acceptable to most Christian denominations:
*belief in [[God the Father]], [[Jesus Christ]] as the [[Son of God]] and the [[Holy Spirit]]
*the [[crucifixion of Jesus|death]], [[Harrowing of Hell|descent into hell]], [[resurrection of Jesus|resurrection]], and [[Ascension of Jesus|ascension]] of Christ
*the holiness of the [[Ecclesia (church)|Church]] and the [[communion of saints]]
*Christ's [[second coming]], the [[Day of Judgement]] and [[salvation]] of the faithful.

{{wikisource|Nicene Creed}}
The [[Nicene Creed]], largely a response to [[Arianism]], was formulated at the Councils of [[First Council of Nicaea|Nicaea]] and [[First Council of Constantinople|Constantinople]] in 325 and 381 respectively<ref>Catholics United for the Faith, [http://www.cuf.org/faithfacts/details_view.asp?ffID=191 "We Believe in One God"]</ref><ref>''Encyclopedia of Religion'', "Arianism".{{Clarifyme|date=August 2008}}</ref> and ratified as the universal creed of [[Christendom]] by the [[Council of Ephesus]] in 431.<ref name="ephesus">''[[Catholic Encyclopedia]]'', "[http://www.newadvent.org/cathen/05491a.htm Council of Ephesus]".</ref>

The [[Chalcedonian Creed]], developed at the [[Council of Chalcedon]] in 451,<ref>[[History of Christianity|Christian History]] Institute, [http://chi.gospelcom.net/DAILYF/2003/10/daily-10-08-2003.shtml ''First Meeting of the Council of Chalcedon''].</ref> though rejected by the [[Oriental Orthodox]] Churches<ref>[[British Orthodox Church]], [http://www.britishorthodox.org/113e.php ''The Oriental Orthodox Rejection of Chalcedon'']</ref>, taught Christ "to be acknowledged in two natures, inconfusedly, unchangeably, indivisibly, inseparably": one divine and one human, and that both natures are perfect but are nevertheless [[Hypostatic union|perfectly united into one person]].<ref>Pope Leo I, [http://www.dailycatholic.org/history/4ecumen2.htm Letter to Flavian'']</ref>

The [[Athanasian Creed]], received in the western Church as having the same status as the Nicene and Chalcedonian, says: "We worship one God in Trinity, and Trinity in Unity; neither confounding the Persons nor dividing the [[Consubstantiality|Substance]]."<ref>''[[Catholic Encyclopedia]]'', "[http://www.newadvent.org/cathen/02033b.htm Athanasian Creed]".</ref>

Most Christians (Roman Catholics, Orthodox and Protestants alike) accept the use of creeds, and subscribe to at least one of the creeds mentioned above.<ref name="UMC - Our Common Heritage as Christians">{{cite web|url = http://archives.umc.org/interior.asp?mid=1806| title = Our Common Heritage as Christians |publisher = The United Methodist Church |accessdate = 2007-12-31}}</ref>
A minority of Protestants, notably [[Restorationists]], a movement formed in the wake of the [[Second Great Awakening]] in the [[19th century in the United States|19th century United States]], oppose the use of creeds.<ref>White, ''[http://www.appiusforum.com/restoration.html The History of the Church]''.</ref>

=== Jesus Christ ===
{{main|Christian views of Jesus|Christology}}

The central tenet of Christianity is the belief in [[Jesus]] as the [[Son of God]] and the [[Messiah]] ([[Christ]]). The title "Messiah" comes from the [[Hebrew language|Hebrew]] word מָשִׁיחַ (''māšiáħ'') meaning ''anointed one''. The Greek translation {{polytonic|''Χριστός''}} (''Christos'') is the source of the English word "[[Christ (title)|Christ]]".<ref name="McGrath4"/>[[Image:Vladimirskaya.jpg|thumb|200px|left|A depiction of Jesus and Mary, the [[Theotokos of Vladimir]] (12th century).]]

Christians believe that, as the Messiah, Jesus was [[anointing|anointed]] by God as ruler and savior of humanity, and hold that Jesus' coming was the fulfillment of [[Messianic prophecies of Jesus|messianic prophecies]] of the [[Old Testament]]. The Christian concept of the Messiah differs significantly from [[Jewish Messiah|the contemporary Jewish concept]]. The core Christian belief is that, through [[Death and Resurrection of Jesus|the death and resurrection of Jesus]], [[original sin|sinful]] humans can be reconciled to God and thereby are offered salvation and the promise of [[Immortality|eternal life]].<ref>Metzger/Coogan, ''Oxford Companion to the Bible'', p. 513, 649.</ref>

While there have been many [[Christian theology|theological]] disputes over the [[Christology|nature of Jesus]] over the first centuries of Christian history, Christians generally believe that Jesus is [[Incarnation (Christianity)|God incarnate]] and "[[Hypostatic union|true God and true man]]" (or both fully divine and fully human). Jesus, having become [[Incarnation (Christianity)|fully human]], suffered the pains and temptations of a mortal man, yet he did not [[sin]]. As fully God, he defeated death and rose to life again. According to the [[Bible]], "God raised him from the dead,"<ref>{{bibleverse||Acts|2:24}}, {{bibleverse-nb||Acts|2:31-32}}, {{bibleverse-nb||Acts|3:15}}, {{bibleverse-nb||Acts|3:26}}, {{bibleverse-nb||Acts|4:10}}, {{bibleverse-nb||Acts|5:30}}, {{bibleverse-nb||Acts|10:40-41}}, {{bibleverse-nb||Acts|13:30}}, {{bibleverse-nb||Acts|13:34}}, {{bibleverse-nb||Acts|13:37}}, {{bibleverse-nb||Acts|17:30-31}}, {{bibleverse||Romans|10:9|NIV}}, {{bibleverse|1|Cor|15:15|NIV}}, {{bibleverse-nb|1|Cor|6:14}}, {{bibleverse|2|Cor|4:14}}, {{bibleverse||Gal|1:1}}, {{bibleverse||Eph|1:20}}, {{bibleverse||Col|2:12}}, {{bibleverse|1|Thess|1:10}}, {{bibleverse||Heb|13:20}}, {{bibleverse|1|Pet|1:3}}, {{bibleverse-nb|1|Pet|1:21}}</ref> he [[Ascension of Jesus Christ|ascended]] to [[heaven]], is "seated at the right hand of the Father"<ref>http://en.wikisource.org/wiki/Nicene_Creed</ref> and will [[Second Coming|return again]]<ref>{{bibleverse||Acts|1:9-11}}</ref> to fulfill the rest of [[Messianic prophecy]] such as the [[Resurrection of the dead]], the [[Last Judgment]] and final establishment of the [[Kingdom of God]].

According to the [[Gospel]]s of [[Gospel of Matthew|Matthew]] and [[Gospel of Luke|Luke]], Jesus was [[Incarnation (Christianity)|conceived]] by the [[Holy Spirit]] and [[Nativity of Jesus|born]] from [[Mary (mother of Jesus)|the Virgin Mary]]. Little of Jesus' childhood is recorded in the [[canonical Gospels]], however [[infancy Gospels]] were popular in antiquity. In comparison, his adulthood, especially the week before his death, are well documented in the Gospels contained within the [[New Testament]]. The Biblical accounts of Jesus' ministry include: [[Baptism of Jesus|his baptism]], [[Miracles attributed to Jesus|miracles]], preaching, [[Ministry of Jesus|teaching, and deeds]].

=== Death and resurrection of Jesus ===
{{main|Crucifixion of Jesus|Resurrection of Jesus}}

[[Image:Cristo Velázquez lou2.jpg|thumb|180px|The Crucifixion by Diego Velázquez (17th century)]]

Christians consider the resurrection of Jesus to be the cornerstone of their faith (see [[1 Corinthians 15]]) and the most important event in human history.<ref>Hanegraaff. ''Resurrection: The Capstone in the Arch of Christianity''.</ref> Among Christian beliefs, the death and resurrection of Jesus are two core events on which much of Christian doctrine and theology is based.<ref name="ACU-Death & Resurrection">{{cite web|url = http://dlibrary.acu.edu.au/research/theology/Walsh.htm| title = The Significance of the Death and Resurrection of Jesus for the Christian|publisher = Australian Catholic University National|accessdate = 2007-05-16}}</ref><ref name="Got Questions-Death & Resurrection">{{cite web|url = http://www.gotquestions.org/resurrection-Christ-important.html| title = Why is the resurrection of Jesus Christ important?|publisher = Got Questions Ministries|accessdate = 2007-05-16}}</ref> According to the [[New Testament]] [[Jesus]] was [[Crucifixion|crucified]], died a physical death, buried within a tomb, and rose from the dead three days later.<ref>{{bibleref2|John|19:30–31|NIV}}, {{bibleref|Mark|16:1|NIV}}, {{bibleref|Mark|16:6|NIV}}</ref> The New Testament mentions several [[resurrection appearances of Jesus]] on different occasions to his [[twelve apostles]] and [[disciple (Christianity)|disciples]], including "more than five hundred brethren at once,"<ref>{{bibleref2|1Corinthians|15:6|NIV|1 Cor. 15:6}}</ref> before Jesus' [[Ascension of Jesus Christ|Ascension]] to [[heaven]]. Jesus' death and resurrection are commemorated by Christians in all worship services, with special emphasis during [[Holy Week]] which includes [[Good Friday]] and [[Easter]] Sunday.

The death and resurrection of Jesus are usually considered the most important events in [[Christian Theology]], partly because they demonstrate that Jesus has power over life and death and therefore has the authority and power to give people [[eternal life]].<ref>{{bibleverse||John|3:16|NIV}}, {{bibleverse-nb||John|5:24|NIV}}, {{bibleverse-nb||John|6:39–40|NIV}}, {{bibleverse-nb||John|6:47|NIV}}, {{bibleverse-nb||John|10:10|NIV}}, {{bibleverse-nb||John|11:25–26|NIV}}, and {{bibleverse-nb||John|17:3|NIV}}.</ref>

Christian churches accept and teach the New Testament account of the resurrection of Jesus with very few exceptions.<ref>This is drawn from a number of sources, especially the early Creeds, the ''Catechism of the Catholic Church'', certain theological works, and various Confessions drafted during the Reformation including the ''Thirty Nine Articles of the Church of England'', works contained in the ''Book of Concord''.</ref>. Some modern scholars use the belief of Jesus' followers in the resurrection as a point of departure for establishing the continuity of the [[historical Jesus]] and the proclamation of the [[early church]].<ref>Fuller, ''The Foundations of New Testament Christology'', p. 11.</ref> Some [[Liberal Christianity|liberal Christians]] do not accept a literal bodily resurrection,<ref>A [[Jesus Seminar]] conclusion: "in the view of the Seminar, he did not rise bodily from the dead; the resurrection is based instead on [[vision hypothesis|visionary experiences]] of [[Simon Peter|Peter]], [[Paul of Tarsus|Paul]], and [[Mary Magdalene|Mary]]."</ref><ref>Funk. ''The Acts of Jesus: What Did Jesus Really Do?''.</ref> seeing the story as richly symbolic and spiritually nourishing [[mythology|myth]]. Arguments over death and resurrection claims occur at many religious [[debate]]s and [[interfaith|interfaith dialogues]].<ref>Lorenzen. ''Resurrection, Discipleship, Justice: Affirming the Resurrection Jesus Christ Today'', p. 13.</ref> [[Paul the Apostle]], an early Christian convert and missionary, wrote, "If Christ was not raised, then all our preaching is useless, and your trust in God is useless."<ref>{{bibleref2|1Cor|15:14|NLT|1 Cor. 15:14}}</ref><ref>Ball/Johnsson (ed.). ''The Essential Jesus''.</ref> The Unitarian church is one of the few in which a resurrection of Jesus is not a doctrine.<ref>[http://www.melbourneunitarian.org.au/node/22 Melbourne Unitarian Peace Memorial Church]</ref>{{Fact|date=August 2008}}

=== Salvation ===
{{main|Salvation}}

[[Protestantism]] teaches that [[salvation|eternal salvation]] is a gift that comes to an individual by [[Divine grace|God's grace]], sometimes defined as "unmerited favor," on the basis of one's personal belief in and dependence on the [[Substitutionary atonement|substitutionary death and resurrection of Jesus Christ]].<ref name=Westminster>McKim, Donald K. ''Westminster Dictionary of Theological Terms." Westminster John Knox Press, 1996.</ref> Salvation in this sense refers to God's activities in bringing humans into right relationship with God and with one another through faith in Jesus Christ. It is the belief that one can be saved (rescued) from [[sin]] and eternal [[death]]. Other concepts used in the study of how salvation is accomplished include conversion, faith, justification, regeneration, and others.<ref name=Westminster/> Many Protestants believe in the "assurance of salvation" — that God can give the confidence that a believer in Jesus as the Christ has truly received salvation.

[[Image:Christianity percentage by country.png|thumb|300px|Christianity [[percentage]] by [[country]].]]

[[Catholicism]] teaches that while in most cases one must be a baptized Catholic to be saved<ref>CCC 846; Vatican II, Lumen Gentium 14</ref>. it is possible in some circumstances for people to be saved who have not been fully initiated into the Catholic Church<ref>"Salvation outside the Church." http://www.catholic.com/library/Salvation_Outside_the_Church.asp</ref>. Catholics generally emphasize the role of works and [[sacraments]] in attaining salvation. The Catholic Church teaches that faith is important, but it also believes that salvation also requires good works and piety such as obedience to the commandments, participation in the sacraments, church attendance, doing penance and giving alms, reciting prayers and so on, in order to merit eternal life.<ref>See quotations from Council of Trent on Justification at http://www.justforcatholics.org/a14.htm</ref>

The formal study of theology of salvation is [[Soteriology]].<ref>''The American Heritage Dictionary of the English Language'', "[http://dictionary.reference.com/browse/Soteriology Soteriology]".</ref>

The crucifixion of Jesus is explained as an [[Atonement|atoning]] [[Sacrifice#Sacrifice in Christianity|sacrifice]], which, in the words of the [[Gospel of John]], "takes away the sins of the world." One's reception of salvation is related to [[justification (theology)|justification]].<ref>Metzger/Coogan, ''Oxford Companion to the Bible'', p. 405.</ref>

The operation and effects of grace are understood differently by different traditions. Roman Catholicism and Eastern Orthodoxy teach the necessity of the [[free will]] to cooperate with grace.<ref>Catechism of the Catholic Church, [http://www.vatican.va/archive/catechism/p3s1c3a2.htm Grace and Justification]</ref> [[Reformed theology]] places distinctive emphasis on grace by teaching that individuals are completely [[total depravity|incapable of self-redemption]], but the grace of God overcomes [[Irresistible grace|even the unwilling heart]].<ref>Westminster Confession, [http://www.pcanet.org/general/cof_chapvi-x.htm#chapx Chapter X]; Spurgeon, ''[http://www.spurgeon.org/calvinis.htm A Defense of Calvinism]''.</ref> [[Arminianism]] takes a synergistic approach while [[Lutheranism]] and most other Protestant doctrines teaches justification by grace alone through [[Sola fide|faith alone]].<ref name=Westminster/><ref>Balge, ''[http://www.wlsessays.net/subjects/IJ/ijsubind.htm#Justification Martin Luther, Augustinian]''.</ref>

=== Trinity ===
{{main|Trinity}}

''Trinity'' refers to the teaching that the one God comprises three distinct, eternally co-existing persons; the ''[[God the Father|Father]]'' (from whom the Son and Spirit proceed), the ''Son'' (incarnate in Jesus Christ), and the ''[[Holy Spirit]]''. Together, these three persons are sometimes called the [[Godhead (Christianity)|Godhead]],<ref>Kelly. ''Early Christian Doctrines''. p. 87-90.</ref><ref>Alexander. ''New Dictionary of Biblical Theology''. p. 514f.</ref><ref>McGrath. ''Historical Theology''. p. 61.</ref> although there is no single term in use in Scripture to denote the unified Godhead.<ref>Metzger/Coogan. ''Oxford Companion to the Bible''. p. 782.</ref> In the words of the [[Athanasian Creed]], an early statement of Christian belief, "the Father is God, the Son is God, and the Holy Spirit is God, and yet there are not three Gods but one God".<ref>Kelly. ''The Athanasian Creed''.</ref>

The [[Trinity]] is an essential doctrine of mainstream Christianity. "Father, Son and Holy Spirit" represents both the [[immanence]] and [[transcendence]] of God. God is believed to be infinite and God's presence may be perceived through the actions of Jesus Christ and the Holy Spirit.<ref>Fowler. ''World Religions: An Introduction for Students''. p. 58.</ref>

According to this doctrine, God is not divided in the sense that each person has a third of the whole; rather, each person is considered to be fully God (see [[Perichoresis]]). The distinction lies in their relations, the Father being unbegotten; the Son being eternally begotten of the Father; and the Holy Spirit proceeding from the Father and (in Western theology) [[Filioque|from the Son]].<ref>Vladimir Lossky; [[Loraine Boettner]].{{Clarifyme|date=August 2008}}</ref> Regardless of this apparent difference, the three 'persons' are each [[eternity|eternal]] and [[omnipotent]].

The word ''trias'', from which ''trinity'' is derived, is first seen in the works of [[Theophilus of Antioch]]. He wrote of "the Trinity of God (the Father), His Word (the Son) and His Wisdom (Holy Spirit)".<ref>Theophilus of Antioch ''Apologia ad Autolycum'' II 15</ref> The term may have been in use before this time. Afterwards it appears in [[Tertullian]].<ref>McManners, ''Oxford Illustrated History of Christianity''. p. 50.</ref><ref>Tertullian ''De Pudicitia'' chapter 21</ref> In the following century the word was in general use. It is found in many passages of [[Origen]].<ref>McManners, ''Oxford Illustrated History of Christianity'', p. 53.</ref>

[[Image:Andrej Rublëv 001.jpg|right|thumb|215px|The "Hospitality of Abraham" by Andrei Rublev: The three angels represent the three persons of God]]

==== Trinitarians ====
{{main|Trinitarianism}}
''Trinitarianism'' denotes those Christians who believe in the concept of the ''[[Trinity]]''. Almost all Christian denominations and Churches hold Trinitarian beliefs. Although the words "Trinity" and "Triune" do not appear in the Bible, theologians beginning in the third century developed the term and concept to facilitate comprehension of the New Testament teachings of God as Father, God as Jesus the Son, and God as the Holy Spirit. Since that time, Christian theologians have been careful to emphasize that Trinity does not imply three gods, nor that each member of the Trinity is one-third of an infinite God; Trinity is defined as one God in three Persons.<ref>Moltman, Jurgen. ''The Trinity and the Kingdom: The Doctrine of God.'' Tr. from German. Fortress Press, 1993. ISBN 080062825X</ref>

==== Non-trinitarians ====
{{main|Nontrinitarianism}}

[[Nontrinitarianism]] refers to [[Christian theology|beliefs systems]] that reject the doctrine of the [[Trinity]]. Various nontrinitarian views, such as [[adoptionism]] or [[modalism]], existed in early Christianity, leading to the disputes about [[Christology]].<ref>Harnack, ''[http://www.ccel.org/ccel/harnack/dogma1.ii.iii.iii.html History of Dogma]''.</ref> Nontrinitarianism later appeared again in the [[Gnosticism]] of the [[Cathars]] in the 11th through 13th centuries, in the [[Age of Enlightenment]] of the 18th century, and in [[Restorationism]] during the 19th century.

=== Scriptures ===
{{main|Bible|Development of the Christian Biblical canon}}

Christianity regards the [[Bible]], a collection of [[Biblical canon|canonical]] books in two parts (the [[Old Testament]] and the [[New Testament]]), as authoritative. It is believed by Christians to have been written by human authors under the inspiration of the Holy Spirit, and therefore for many it is held to be the [[Biblical inerrancy|inerrant]] word of God.<ref>[[Catechism of the Catholic Church]], [http://www.vatican.va/archive/catechism/p1s1c2a3.htm#II ''Inspiration and Truth of Sacred Scripture'' (§105-108)]</ref><ref>Second Helvetic Confession, [http://www.creeds.net/reformed/helvetic/c01.htm ''Of the Holy Scripture Being the True Word of God'']</ref><ref>[[Chicago Statement on Biblical Inerrancy]], [http://www.reformed.org/documents/icbi.html ''online text'']</ref> The [[Books of the Bible|books]] that are considered canon in the Bible vary depending upon the denomination using or defining it. These variations are a reflection of the range of [[traditions]] and [[Ecumenical council|councils]] that have convened on the subject. The Bible always includes books of the Jewish scriptures, the [[Tanakh]], and includes additional books and reorganizes them into two parts: the books of the [[Old Testament]] primarily sourced from the Tanakh (with some variations), and the 27 books of the [[New Testament]] containing books originally written primarily in [[Greek language|Greek]]<ref>[http://www.pcusa.org/101/101-bible.htm PC(USA) - Presbyterian 101 - What is The Bible?]</ref>. The Roman Catholic and Orthodox canons include other books from the [[Septuagint]] which Roman Catholics call [[Deuterocanonical books|Deuterocanonical]].<ref name="Canon">Bruce, ''The Canon of Scripture''; ''Catechism of the Catholic Church'', [http://www.vatican.va/archive/catechism/p1s1c2a3.htm#IV, "The Canon of Scripture", § 120]</ref> Protestants consider these books [[Biblical apocrypha|apocryphal]]. Some versions of the Christian Bible have a separate Apocrypha section for the books not considered canonical by the publisher.<ref>Metzger/Coogan, ''Oxford Companion to the Bible''. p. 39.</ref>

==== Roman Catholic interpretation ====
In antiquity, two schools of exegesis developed in [[Alexandria]] and [[School of Antioch|Antioch]]. Alexandrine interpretation, exemplified by [[Origen]], tended to read Scripture [[allegory|allegorically]], while Antiochene interpretation adhered to the literal sense, holding that other meanings (called ''theoria'') could only be accepted if based on the literal meaning.<ref>Kelly. ''Early Christian Doctrines''. p. 69-78.</ref>

[[Roman Catholic]] theology distinguishes two senses of scripture: the literal and the spiritual.<ref>Catechism of the Catholic Church, [http://www.vatican.va/archive/catechism/p1s1c2a3.htm#III, ''The Holy Spirit, Interpreter of Scripture'' § 115-118].</ref>

The ''literal'' sense of understanding scripture is the meaning conveyed by the words of Scripture. The ''spiritual'' sense is further subdivided into:
*the ''[[allegory|allegorical]]'' sense, which includes [[Typology (theology)|typology]]. An example would be the [[Passage of the Red Sea|parting of the Red Sea]] being understood as a "type" (sign) of baptism.<ref>{{niv|1_Corinthians|10:2|1 Corinthians 10:2}}</ref>
*the ''[[moral]]'' sense, which understands the scripture to contain some ethical teaching.
*the ''[[anagoge|anagogical]]'' sense, which applies to [[eschatology]], eternity and the [[Apocalypse|consummation of the world]]

Regarding [[exegesis]], following the rules of sound interpretation, Roman Catholic theology holds:
*the injunction that all other senses of sacred scripture are based on the ''literal''<ref>Thomas Aquinas, [http://www.newadvent.org/summa/100110.htm "Whether in Holy Scripture a word may have several senses"]</ref><ref>''Catechism of the Catholic Church,'' [http://www.vatican.va/archive/catechism/p1s1c2a3.htm#III §116]</ref>
*that the historicity of the Gospels must be absolutely and constantly held<ref>[[Second Vatican Council]], [http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19651118_dei-verbum_en.html ''Dei Verbum'' (V.19)].</ref>
*that scripture must be read within the "living Tradition of the whole Church"<ref> ''Catechism of the Catholic Church'', [http://www.vatican.va/archive/catechism/p1s1c2a3.htm#III "The Holy Spirit, Interpreter of Scripture" § 113].</ref> and
*that "the task of interpretation has been entrusted to the bishops in communion with the successor of Peter, the [[Bishop of Rome]]".<ref>''Catechism of the Catholic Church,'' [http://www.vatican.va/archive/catechism/p1s1c2a2.htm#III "The Interpretation of the Heritage of Faith" § 85].</ref>

==== Protestant interpretation ====
;Clarity of Scripture:Protestant Christians believe that the Bible is a self-sufficient revelation, the final authority on all Christian doctrine, and [[Revelation|revealed all truth]] necessary for salvation. This concept is known as [[Sola scriptura]].<ref>Mathison. ''The Shape of Sola Scriptura''.{{Clarifyme|date=August 2008}}</ref> Protestants characteristically believe that ordinary believers may reach an adequate understanding of Scripture because Scripture itself is clear (or "perspicuous"), because of the help of the Holy Spirit, or both. Martin Luther believed that without God's help Scripture would be "enveloped in darkness."<ref name="Foutz" /> He advocated "one definite and simple understanding of Scripture."<ref name="Foutz">Foutz, [http://www.quodlibet.net/luther.shtml '' Martin Luther and Scripture''].</ref> [[John Calvin]] wrote, "all who...follow the Holy Spirit as their guide, find in the Scripture a clear light."<ref>John Calvin, [http://www.ccel.org/c/calvin/comment3/comm_vol45/htm/vii.iv.iv.htm '' Commentaries on the Catholic Epistles'' 2 Peter 3:14-18]</ref> The Second Helvetic (Latin for "Swiss")<ref>http://mb-soft.com/believe/txh/helvconf.htm Article about Helvetic confessions</ref> Confession, composed by the pastor of the Reformed church in Zurich (successor to Protestant reformer [[Zwingli]]) was adopted as a declaration of doctrine by most European Reformed churches.<ref>Second Helvetic Confession, [http://www.creeds.net/reformed/helvetic/c02.htm ''Of Interpreting the Holy Scriptures; and of Fathers, Councils, and Traditions'']</ref>

;Original intended meaning:Protestants stress the meaning conveyed by the words of Scripture, the [[historical-grammatical method]].<ref>Sproul. ''Knowing Scripture'', p. 45-61; Bahnsen, ''[http://www.cmfnow.com/articles/pt173.htm A Reformed Confession Regarding Hermeneutics'' (article 6)].</ref> The historical-grammatical method or grammatico-historical method is a effort in [[Biblical hermeneutics]] to find the intended original meaning in the text. <ref> {{Cite book
| publisher = Baker Book House
| isbn = 0801034132
| last = Elwell
| first = Walter A.
| title = Evangelical Dictionary of Theology
| location = Grand Rapids, Mich.
| date = 1984
}}</ref> This original intended meaning of the text is drawn out through examination of the passage in light of the grammatical and syntactical aspects, the historical background, the literary genre as well as theological (canonical) considerations.<ref>{{Cite book
| publisher = Academie Books
| isbn = 9780310341604
| last = Johnson
| first = Elliott
| title = Expository hermeneutics : an introduction
| location = Grand Rapids Mich.
}} </ref> The historical-grammatical method distinguishes between the one original meaning and the significance of the text. The significance of the text includes the ensuing use of the text or application. The original passage is seen as having only a single meaning or sense. As Milton S. Terry said: "A fundamental principle in grammatico-historical exposition is that the words and sentences can have but one significance in one and the same connection. The moment we neglect this principle we drift out upon a sea of uncertainty and conjecture." <ref>{{Cite book
| publisher = Zondervan Pub. House
| last = Terry
| first = Milton
| title = Biblical hermeneutics : a treatise on the interpretation of the Old and New Testaments
| location = Grand Rapids Mich.
| date = 1974
}} page 205 </ref> Technically speaking, the grammatical-historical method of interpretation is distinct from the determination of the passage's significance in light of that interpretation. Taken together, both define the term (Biblical) hermeneutics. <ref>{{Cite book
| publisher = Baker Book House
| isbn = 0801034132
| last = Elwell
| first = Walter A.
| title = Evangelical Dictionary of Theology
| location = Grand Rapids, Mich.
| date = 1984
}} p. 565</ref>

Some Protestant interpreters make use of typology.<ref>E.g., in his [http://eword.gospelcom.net/comments/matthew/mh/matthew1.htm commentary on Matthew 1] (§III.3) [[Matthew Henry]] interprets the twin-sons of Judah, Phares and Zara, as an allegory of the Gentile and [[Jewish Christians]]. For a contemporary treatment, see Glenny, ''[http://www.biblicalstudies.org.uk/article_typology_glenny.html Typology: A Summary Of The Present Evangelical Discussion]''.</ref>

=== Afterlife and Eschaton ===
{{main|Christian eschatology}}

Most Christians believe that human beings experience divine judgement and are rewarded either with [[heaven|eternal life]] or [[hell|eternal damnation]]. This includes the [[Last Judgment|general judgement]] at the [[Resurrection of the dead]] (see below) as well as the belief (held by Catholics<ref name="CEParticularJudgement">''[[Catholic Encyclopedia]]'', "[http://www.newadvent.org/cathen/08550a.htm Particular Judgment]".</ref><ref name="Ott">Ott, ''Grundriß der Dogmatik'', p. 566.</ref>, Orthodox<ref>David Moser, ''[http://www.orthodox.net/articles/about-prayer-for-the-dead.html What the Orthodox believe concerning prayer for the dead]''.</ref><ref>Ken Collins, ''[http://www.kencollins.com/question-45.htm What Happens to Me When I Die?]''.</ref> and some Protestants) in a [[particular judgment|judgement particular to the individual soul]] upon physical death.

In Roman Catholicism, those who die in a state of grace, i.e. without any mortal sin separating them from God, but are still imperfectly purified from the effects of sin, undergo purification through the intermediate state of [[purgatory]] to achieve the holiness necessary for entrance into God's presence.<ref>[http://www.vatican.va/holy_father/john_paul_ii/audiences/1999/documents/hf_jp-ii_aud_04081999_en.html Audience of 4 August 1999]</ref> Those who have attained this goal are called ''saints'' (Latin ''sanctus'', "holy").<ref>''[[Catholic Encyclopedia]]'', "[http://www.newadvent.org/cathen/04171a.htm The Communion of Saints]".</ref>

Some churches who do not believe in particular judgment, e.g. [[Jehovahs Witnesses]], hold that the [[soul sleep]]s until this time.<ref name="spitz">Spitz. ''The Protestant Reformation''.{{Clarifyme|date=August 2008}}</ref> These groups avoid the term ''saints''.{{Fact|date=September 2008}}

Christians believe that at the [[Second Coming|second coming of Christ]] at the [[eschatology|end of time]], all who have died will be [[Resurrection of the dead|resurrected bodily from the dead]] for the [[Last Judgment]], whereupon Jesus will fully establish the [[Kingdom of God]] in fulfillment of [[Bible prophecy|scriptural prophecies]].<ref name="res">[[Thomas Aquinas]], [http://www.newadvent.org/summa/5.htm ''Summa Theologicum, Supplementum Tertiae Partis''] questions 69 through 99</ref><ref>{{cite web | last =Calvin | first =John | authorlink = | coauthors = | title =Institutes of the Christian Religion, Book Three, Ch. 25 | work = | publisher =www.reformed.org | date = | url =http://www.reformed.org/books/institutes/books/book3/bk3ch25.html | format = | doi = | accessdate =2008-01-01 }}</ref>

[[Universal Reconciliation]], also called [[Apocatastasis#Christianity|Apocatastasis]], is the view that all will eventually experience salvation, rejecting the concept that hell is everlasting.<ref>Farrar. ''[http://www.tentmaker.org/books/mercyandjudgment/mercy_and_judgment_ch1.html Mercy and Judgment]'', p. 378-382.</ref><ref>Talbott. ''[http://www.willamette.edu/~ttalbott/PICTURES.pdf Three Pictures of God in Western Theology]'', p. 13-15.</ref> Such a view was held in the 3rd century by [[Origen]] but was condemned as heretical. The notion was revived after the Reformation, e.g. by the [[Anabaptist]] theologian [[Hans Denck]]. Christians espousing this view are known as Universalists.<ref> http://www.auburn.edu/~allenkc/chr-univ.html, retrieved 11 April 2009</ref>

== Worship ==
{{main|Christian worship}}
[[Justin Martyr]] described 2nd century Christian [[liturgy]] in his ''[[First Apology]]'' (''c''. 150) to [[Roman Emperor|Emperor]] [[Antoninus Pius]], and his description remains relevant to the basic structure of Christian liturgical worship:

[[Image:Thebible33.jpg|200px|left|thumb|Samples of Christian religious objects- The [[Bible|Holy Bible]], a [[Crucifix]], and a [[Rosary]].]]

: "And on the day called Sunday, all who live in cities or in the country gather together to one place, and the memoirs of the apostles or the writings of the prophets are read, as long as time permits; then, when the reader has ceased, the president verbally instructs, and exhorts to the imitation of these good things. Then we all rise together and pray, and, as we before said, when our prayer is ended, bread and wine and water are brought, and the president in like manner offers prayers and thanksgivings, according to his ability, and the people assent, saying [[Amen]]; and there is a distribution to each, and a participation of that over which thanks have been given, and to those who are absent a portion is sent by the deacons. And they who are well to do, and willing, give what each thinks fit; and what is collected is deposited with the president, who succours the orphans and widows and those who, through sickness or any other cause, are in want, and those who are in bonds and the strangers sojourning among us, and in a word takes care of all who are in need."<ref name=justin>Justin Martyr, [http://www.earlychristianwritings.com/text/justinmartyr-firstapology.html ''First Apology''] §LXVII</ref>

Thus, as Justin described, Christians assemble for communal worship on Sunday, the day of the resurrection, though other liturgical practices often occur outside this setting. Scripture readings are drawn from the [[Old Testament|Old]] and [[New Testament]]s, but especially the Gospels. Often these are arranged on an [[annual cycle]], using a book called a [[lectionary]]. Instruction is given based on these readings, called a [[sermon]], or homily. There are a variety of congregational [[prayer]]s, including thanksgiving, confession, and intercession, which occur throughout the service and take a variety of forms including recited, responsive, silent, or sung. The [[Lord's Prayer]], or Our Father, is regularly prayed. The [[Eucharist]] (called [[Holy Communion]], or the [[Eucharist|Lord's Supper]]) is the part of liturgical worship that consists of a consecrated meal, usually bread and wine. Justin Martyr described the Eucharist:

{{cquote|"And this food is called among us Eukaristia [the Eucharist], of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing that is for the remission of sins, and unto regeneration, and who is so living as Christ has enjoined. For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Saviour, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh."<ref name=justin/>}}

Some [[Christian denominations]] view communion as indicating those who are already united in the church, restricting participation to their members not in a state of [[mortal sin]] ([[closed communion]]). Most other churches view communion as a means to unity, rather than an end, and invite all Christians or even anyone to participate ([[open communion]]). In some denominations, participation is decided by prior arrangement with a church leader.

Some groups depart from this traditional liturgical structure. A division is often made between "[[High church|High]]" [[church service]]s, characterized by greater solemnity and ritual, and "[[Low church|Low]]" services, but even within these two categories there is great diversity in forms of worship. [[Seventh-day Adventist Church|Seventh-day Adventists]] meet on Saturday (the original [[Sabbath in Christianity|Sabbath]]), while others do not meet on a weekly basis. [[Charismatic movement|Charismatic]] or [[Pentecostal]] congregations may spontaneously feel led by the Holy Spirit to action rather than follow a formal order of service, including spontaneous prayer. [[Society of Friends|Quakers]] sit quietly until moved by the Holy Spirit to speak. Some [[Evangelicalism|Evangelical]] services resemble concerts with [[Christian rock|rock and pop music]], dancing, and use of multimedia. For groups which do not recognize a priesthood distinct from ordinary believers the services are generally lead by a [[minister of religion|minister]], [[preacher]], or [[pastor]]. Still others may lack any formal leaders, either in principle or by local necessity. Some churches use only [[a cappella]] music, either on principle (e.g. many [[Churches of Christ]] object to the use of instruments in worship) or by tradition (as in Orthodoxy).

Worship can be varied for special events like [[baptism]]s or [[wedding]]s in the service or significant [[Calendar of saints|feast days]]. In the [[Early Christianity|early church]] Christians and those yet to complete initiation would separate for the Eucharistic part of the worship. In many churches today, adults and children will separate for all or some of the service to receive age-appropriate teaching. Such children's worship is often called [[Sunday school]] or [[Sabbath School|Sabbath school]] (Sunday schools are often held before rather than during services).

=== Sacraments ===
{{main|Sacrament}}
{{seealso|Sacraments of the Catholic Church}}
[[Image:Fractio-panis1.JPG|right|thumb|200px|The [[Eucharist]]]]
In [[Christian]] belief and practice, a '''sacrament''' is a [[rite]], instituted by Christ, that mediates [[divine grace|grace]], constituting a [[Sacred Mysteries|sacred mystery]]. The term is derived from the [[Latin]] word ''sacramentum'', which was used to translate the Greek word for ''mystery''. Views concerning both what rites are sacramental, and what it means for an act to be a sacrament vary among Christian denominations and traditions.<ref name="ODCC1435">Cross/Livingstone. ''The Oxford Dictionary of the Christian Church''. p. 1435f.</ref>

The most conventional functional definition of a sacrament is that it is an outward sign, instituted by Christ, that conveys an inward, spiritual grace through Christ. The two most widely accepted sacraments are [[Baptism]] and the [[Eucharist]], however, the majority of Christians recognize seven Sacraments or Divine Mysteries: [[Baptism]], [[Confirmation (Christian sacrament)|Confirmation]] ([[Chrismation]] in the [[Orthodox Church|Orthodox]] tradition), and the [[Eucharist]], [[Holy Orders]], [[Confession|Reconciliation of a Penitent]] (confession), [[Anointing of the Sick]], and [[Christian views of marriage|Matrimony]].<ref name="ODCC1435" /> Taken together, these are the [[Seven Sacraments]] as recognised by churches in the [[High church]] tradition - notably [[Sacraments of the Catholic Church|Roman Catholic]], [[Orthodox Church|Eastern Orthodox]], [[Oriental Orthodox]], [[Independent Catholic Churches|Independent Catholic]], [[Old Catholic]] and some [[Anglican sacraments|Anglican]]s. Most other denominations and traditions typically affirm only Baptism and Eucharist as sacraments, while some Protestant groups, such as the Quakers, reject sacramental theology.<ref name="ODCC1435" /> Some [[Christian denominations]] who believe these rites do not communicate grace prefer to call them ''[[Ordinance (Christian)|ordinances]]''.

=== Liturgical calendar ===
{{main|Liturgical year}}

Roman Catholics, Anglicans, Eastern Christians, and traditional Protestant communities frame worship around a [[Liturgical year|liturgical calendar]]. This includes [[Holy Day of Obligation|holy days]], such as [[Solemnity|solemnities]] which commemorate an event in the life of Jesus or the [[saint]]s, periods of [[fasting]] such as [[Lent]], and other pious events such as [[memoria]] or lesser festivals commemorating saints. Christian groups that do not follow a liturgical tradition often retain certain celebrations, such as [[Christmas]], [[Easter]] and [[Pentecost]]. A few churches make no use of a liturgical calendar.<ref>Hickman. ''Handbook of the Christian Year''.</ref>

=== Symbols ===
{{main|Christian symbolism}}
[[Image:Ephesus IchthysCrop.jpg|thumb|right|An early circular [[ichthys]] symbol, created by combining the Greek letters ΙΧΘΥΣ into a wheel. [[Ephesus]], Asia Minor.]]

The [[Christian cross|cross]], which is today one of the most widely recognised symbols in the world, was used as a Christian symbol from the earliest times.<ref>[http://www.ccel.org/fathers2/ANF-04/anf04-34.htm ANF04. Fathers of the Third Century: Tertullian, Part Fourth; Minucius Felix; Commodian; Origen, Parts First and Second | Christian Classics Ethereal Library]</ref><ref>Minucius Felix speaks of the cross of Jesus in its familiar form, likening it to objects with a crossbeam or to a man with arms outstretched in prayer ([http://www.ccel.org/fathers2/ANF-04/anf04-34.htm#P5713_906729 Octavius of Minucius Felix,] chapter XXIX).</ref> Tertuallian, in his book ''De Corona'', tells how it was already a tradition for Christians to trace repeatedly on their foreheads the sign of the cross.<ref>"At every forward step and movement, at every going in and out, when we put on our clothes and shoes, when we bathe, when we sit at table, when we light the lamps, on couch, on seat, in all the ordinary actions of daily life, we trace upon the forehead the sign." (Tertullian, [http://www.ccel.org/ccel/schaff/anf03.iv.vi.iii.html ''De Corona'', chapter 3])</ref> Although the cross was known to the early Christians, the [[crucifix]] did not appear in use until the fifth century.<ref name="soc">Dilasser. ''The Symbols of the Church''.</ref>

Among the symbols employed by the primitive Christians, that of the fish seems to have ranked first in importance. From monumental sources such as tombs it is known that the symbolic fish was familiar to Christians from the earliest times. The fish was depicted as a Christian symbol in the first decades of the second century.<ref name="cefish">''[[Catholic Encyclopedia]]'', "[http://www.newadvent.org/cathen/06083a.htm Symbolism of the Fish]".</ref> Its popularity among Christians was due principally, it would seem, to the famous acrostic consisting of the initial letters of five Greek words forming the word for fish (Ichthys), which words briefly but clearly described the character of Christ and the claim to worship of believers: ''Iesous Christos Theou Yios Soter'', meaning, ''Jesus Christ, Son of God, Saviour''.<ref name="cefish" />

Christians from the very beginning adorned their [[catacombs|tombs]] with paintings of Christ, of the saints, of scenes from the [[Bible]] and allegorical groups. The catacombs are the cradle of all Christian art. The first Christians had no prejudice against images, pictures, or statues. The idea that they must have feared the danger of idolatry among their new converts is disproved in the simplest way by the pictures even statues, that remain from the first centuries.<ref name="ceimage">''[[Catholic Encyclopedia]]'', "[http://www.newadvent.org/cathen/07664a.htm Veneration of Images].</ref> Other major Christian symbols include the [[Chrismon|chi-rho monogram]], the [[dove]] (symbolic of the Holy Spirit), the sacrificial lamb (symbolic of Christ's sacrifice), the [[vine]] (symbolising the necessary connectedness of the Christian with Christ) and many others. These all derive from writings found in the [[New Testament]].<ref name="soc"/>

== History and origins ==
{{main|History of Christianity}}

[[Image:Ignatius.jpg|thumb|right|[[Martyr]]dom of [[Ignatius of Antioch|St. Ignatius]], bishop of Antioch appointed by [[St. Peter]].]]

===Early Church and Christological Councils ===

Christianity began as a [[Jewish]] sect in the eastern [[History of the Mediterranean region|Mediterranean]] in the mid-first century.<ref name="Robinson"/><ref name="Esler"/><ref name="name"/> Under the leadership of the Apostles, especially [[Saint Peter|Peter]] and [[Paul the Apostle|Paul]], and the early [[bishop]]s, which they saw as [[Apostolic Succession|successors]] of the [[Twelve Apostles]].

From the beginning, Christians were subject to various [[Persecution of Christians|persecutions]]. This involved even death for Christians such as [[Stephen]]<ref>{{bibleverse||Acts|7:59}}</ref> and [[James, son of Zebedee]].<ref>{{bibleverse||Acts|12:2}}</ref> Larger-scale persecutions followed at the hands of the authorities of the [[Roman Empire]], beginning with the year 64, when [[Emperor Nero]] blamed them for the [[Great Fire of Rome]]. According to Church tradition, it was under Nero's persecution that early Church leaders [[St. Peter|Peter]] and [[Paul of Tarsus|Paul]] were each martyred in [[Rome]]. Further widespread [[Persecution of early Christians by the Romans|persecutions]] of the Church occurred under nine subsequent Roman emperors, most intensely under [[Decius]] and [[Diocletian]]. From the year 150, Christian teachers began to produce theological and apologetic works aimed at defending the faith. These authors are known as the [[Church Fathers]], and study of them is called Patristics. Notable early Fathers include [[Ignatius of Antioch]], [[Polycarp]], [[Justin Martyr]], [[Irenaeus]], [[Tertullian]], [[Clement of Alexandria]] and [[Origen]].

Christianity was legalized in the fourth century, when [[Constantine I]] issued an [[Edict of Milan|edict of toleration]] in 313. On 27 February 380, Emperor [[Theodosius I]] enacted a law establishing Catholic Christianity as the official religion of the Roman Empire.<ref>[http://www.fordham.edu/halsall/source/theodcodeXVI.html Theodosian Code XVI.i.2], in: Bettenson. ''Documents of the Christian Church''. p. 31.</ref> From at least the 4th century, Christianity has played a prominent role in the [[history of Western civilization|shaping of Western civilization]].<ref name="Orlandis">Orlandis, ''A Short History of the Catholic Church'' (1993), preface.</ref>

Constantine was also instrumental in the convocation of the [[First Council of Nicaea]] in 325, which sought to address the [[Arianism|Arian]] heresy and formulated the [[Nicene Creed]], which is still used by the [[Roman Catholic Church]], [[Eastern Orthodoxy]], [[Anglican Communion]], and many [[Protestant]] churches.<ref name="UMC - Our Common Heritage as Christians"/> Nicaea was the first of a series of [[Ecumenical council|Ecumenical (worldwide) Councils]] which formally defined critical elements of the theology of the Church, notably concerning [[Christology]].<ref name= "McManners37">McManners, ''Oxford Illustrated History of Christianity'', p. 37f.</ref> The [[Assyrian Church of the East]] did not accept the third and following Ecumenical Councils, and are still separate today.

===Early Middle Ages===
With the decline and fall of the Roman Empire in the west, the papacy became a political player, first visible in [[Pope Leo I|Pope Leo]]'s diplomatic dealings with [[Attila the Hun|Huns]] and [[Vandals]].<ref name = "Gonzalez-p238"/> The church also entered into a long period of missionary activity and expansion among the former barbarian tribes. Catholicism spread among the [[Germanic peoples]] (initially in competition with Arianism<ref name = "Gonzalez-p238">Gonzalez, ''The Story of Christianity'', p. 238-242.</ref>), the [[Celts|Celtic]] and [[Slavic peoples]], the [[Hungarians]] and the [[Scandinavia]]n and [[Baltic peoples]].

Around 500, [[St. Benedict]] set out his Monastic Rule, establishing a system of regulations for the foundation and running of [[monasteries]].<ref name = "Gonzalez-p238"/> [[Monasticism]] became a powerful force throughout Europe,<ref name = "Gonzalez-p238"/> and gave rise to many early centers of learning, most famously in [[Ireland]], [[Scotland]] and [[Gaul]], contributing to the [[Carolingian Renaissance]] of the 9th century.

From the 7th century onwards, [[Islam]] conquered the Christian lands of the Middle East, North Africa and much of Spain<ref>Gonzalez, ''The Story of Christianity'', p. 248-250.</ref>, resulting in oppression of Christianity and numerous military struggles, including the [[Crusades]], the Spanish [[Reconquista]] and wars against the [[Turks]].

The [[Middle Ages]] brought about major changes within the church. [[Pope Gregory the Great]] dramatically reformed ecclesiastical structure and administration.<ref>Gonzalez, ''The Story of Christianity'', p. 244-247.</ref> In the early 8th century, [[iconoclasm]] became a divisive issue, when it was sponsored by the [[Byzantium|Byzantine]] emperors. The [[Second Council of Nicaea|Second Ecumenical Council of Nicaea]] (787) finally pronounced in favour of icons.<ref>Gonzalez, ''The Story of Christianity'', p. 260.</ref> In the early 10th century, western monasticism was further rejuvenated through the leadership of the great Benedictine monastery of [[Cluny]].<ref>Gonzalez, ''The Story of Christianity'', p. 278-281.</ref>

===High and Late Middle Ages===
In the west, from the 11th century onward, older cathedral schools developed into [[universities]] (see [[University of Paris]], [[University of Oxford]], and [[University of Bologna]].) Originally teaching only [[theology]], these steadily added subjects including [[medicine]], [[philosophy]] and [[law]], becoming the direct ancestors of modern western institutions of learning.<ref>Gonzalez, ''The Story of Christianity'', p. 305, 312, 314f..</ref>

Accompanying the rise of the "new towns" throughout Western Europe, [[mendicant order]]s were founded, bringing the [[Consecrated life (Catholic Church)|consecrated religious life]] out of the monastery and into the new urban setting. The two principal mendicant movements were the [[Franciscans]]<ref>Gonzalez, ''The Story of Christianity'', p. 303-307, 310f., 384-386.</ref> and the [[Dominican Order|Dominicans]]<ref>Gonzalez, ''The Story of Christianity'', p. 305, 310f., 316f.</ref> founded by [[St. Francis]] and [[St. Dominic]] respectively. Both orders made significant contributions to the development of the great universities of Europe. Another new order were the [[Cistercians]], whose large isolated monasteries spearheaded the settlement of former wilderness areas. In this period church building and ecclesiastical architecture reached new heights, culminating in the orders of [[Romanesque architecture|Romanesque]] and [[Gothic architecture]] and the building of the great European cathedrals.<ref>Gonzalez, ''The Story of Christianity'', p. 321-323, 365f.</ref>

[[Image:CouncilofClermont.jpg|thumb|right|180px|[[Pope Urban II]] at the [[Council of Clermont]], where he preached the [[First Crusade]].]]
From 1095 under the pontificate of [[Urban II]], the [[Crusades]] were launched.<ref>Gonzalez, ''The Story of Christianity'', p. 292-300.</ref> These were a series of military campaigns in the [[Holy Land]] and elsewhere, initiated in response to pleas from the Byzantine Emperor [[Alexios I]] for aid against [[Turkish people|Turkish]] expansion. The Crusades ultimately failed to stifle [[Islam]]ic aggression and even contributed to Christian enmity with the sacking of [[Constantinople]] during the [[Fourth Crusade]].<ref>Riley-Smith. ''The Oxford History of the Crusades''.</ref>

Over a period stretching from the 7th to the 13th century, the Christian Church underwent gradual alienation, resulting in a [[East-West Schism|schism]] dividing it into a [[Western Christianity|Western]], largely Latin branch, the Roman Catholic Church, and an [[Eastern Christianity|Eastern]], largely Greek, branch, the [[Eastern Orthodox Church|Orthodox Church]]. These two churches disagree on a number of administrative, liturgical, and doctrinal issues, most notably [[papal primacy|papal primacy of jurisdiction]].<ref name="Orthodox Information Centre-Great Schism">{{cite web|url = http://www.orthodoxinfo.com/general/greatschism.aspx| title = The Great Schism: The Estrangement of Eastern and Western Christendom|publisher = Orthodox Information Centre|accessdate = 2007-05-26}}</ref><ref name="SandSp91">Duffy, ''Saints and Sinners'' (1997), p. 91</ref> The [[Second Council of Lyon]] (1274) and the [[Council of Florence]] (1439) attempted to reunite the churches, but in both cases the Eastern Orthodox refused to implement the decisions and the two principal churches remain in schism to the present day. However, the Roman Catholic Church has achieved union with various [[Eastern Catholic Churches|smaller eastern churches]].

Beginning around 1184, following the crusade brought about by the [[Cathars|Cathar]] heresy,<ref>Gonzalez, ''The Story of Christianity'', p. 300, 304-305.</ref> various institutions, broadly referred to as the [[Inquisition]], were established with the aim of suppressing [[heresy]] and securing religious and doctrinal unity within Christianity through [[religious conversion|conversion]] and prosecution.<ref>Gonzalez, ''The Story of Christianity'', p. 310, 383, 385, 391.</ref>

=== Protestant Reformation and Counter-Reformation ===
{{Main|Protestant Reformation|Counter-Reformation}}
[[Image:Nicaea icon.jpg|right|thumb|An icon depicting the [[First Council of Nicaea]]]]

The 15th-century [[Renaissance]] brought about a renewed interest in ancient and classical learning. Another major schism, the [[Protestant Reformation|Reformation]], resulted in the splintering of the Western Christendom into several [[Christian denominations]].<ref name="Simon-120-121">Simon. ''Great Ages of Man: The Reformation''. p. 7.</ref> [[Martin Luther]] in 1517 [[95 Theses|protested]] against the sale of [[indulgences]] and soon moved on to deny several key points of Roman Catholic [[doctrine]]. Others like [[Zwingli]] and [[Calvin]] further criticized Roman Catholic teaching and worship. These challenges developed into the movement called [[Protestantism]], which repudiated the [[papal primacy|primacy of the pope]], the role of tradition, the [[seven sacraments]], and other doctrines and practices.<ref name="Simon">Simon. ''Great Ages of Man: The Reformation''. p. 39, 55-61.</ref> [[English Reformation|Reformation in England]] began in 1534, when [[King Henry VIII]] had himself [[Act of Supremacy|declared head]] of the [[Church of England]]. Beginning in 1536, the monasteries throughout England, [[Wales]], and [[Ireland]] were [[Dissolution of the monasteries|dissolved]]. <ref name="Schama">Schama. ''A History of Britain''. p. 306-310.</ref>

Partly in response to the [[Protestant Reformation]], the Roman Catholic Church engaged in a substantial process of reform and renewal, known as the [[Counter-Reformation]] or Catholic Reform.<ref name="Bokenkotter242">Bokenkotter, ''A Concise History of the Catholic Church'', p. 242-244.</ref> The [[Council of Trent]] clarified and reasserted Roman Catholic doctrine. During the following centuries, competition between Roman Catholicism and Protestantism became deeply entangled with political struggles among European states.<ref name="Simon3">Simon. ''Great Ages of Man: The Reformation''. p. 109-120.</ref>

Meanwhile, the discovery of America by [[Christopher Columbus]] in 1492 brought about a new wave of missionary activity. Partly from missionary zeal, but under the impetus of [[Colonialism|colonial expansion]] by the European powers, Christianity spread to the Americas, Oceania, [[East Asia]], and [[sub-Saharan Africa]].

Throughout Europe, the divides caused by the Reformation led to outbreaks of [[religious violence]] and the establishment of separate state religions in Western Europe: [[Lutheranism]] in parts of Germany and in Scandinavia and [[Anglicanism]] in England in 1534. Ultimately, these differences led to the outbreak of [[religious war|conflict]]s in which religion played a key factor. The [[Thirty Years' War]], the [[English Civil War]], and the [[French Wars of Religion]] are prominent examples. These events intensified the [[Christian debate on persecution and toleration]].<ref>A general overview about the English discussion is given in Coffey, ''Persecution and Toleration in Protestant England 1558-1689''.</ref>

===Christianity in the Modern Era===

In the [[Modern Era]], Christianity was confronted with various forms of [[skepticism]] and with certain modern [[Ideology|political ideologies]] such as [[liberalism]], [[nationalism]] and [[socialism]]. Events ranged from mere [[anti-clericalism]] to violent outbursts against Christianity such as the [[Dechristianisation of France during the French Revolution|Dechristianisation]] during the [[French Revolution]]<ref>Mortimer Chambers, ''The Western Experience'' (vol. 2) chapter 21.</ref>, the [[Spanish Civil War]], and general hostility of Marxist movements, especially [[Russian Revolution (1917)|the Russian Revolution]].

Christian commitment in Europe dropped as modernity and secularism came into their own{{Clarifyme|date=May 2008}} in Western Europe, while religious commitments in America have been generally high in comparison to Western Europe. The late 20th century has shown the shift of Christian adherence to the Third World and southern hemisphere in general, with western civilization no longer the chief standard bearer of Christianity.

==Demographics==
{{see|Christianity by country}}


With an estimated number of adherents that ranges between 1.5 billion<ref name="Adherents.com Christians">[http://www.adherents.com/Na/Na_173.html Adherents.com{{ndash}} Number of Christians in the world]</ref> and 2.1 billion,<ref name="Adherents.com Christians"/> split into around 34,000 separate [[Christian denominations|denominations]], Christianity is the [[major religious groups|world's largest religion]].<ref name="Adherents - Religion Sizes">{{cite web|url = http://www.adherents.com/Religions_By_Adherents.html| title = Major Religions Ranked by Size|publisher = Adherents|accessdate = 2007-12-31}}</ref> The Christian share of the world's population has stood at around 33 per cent for the last hundred years. This masks a major shift in the demographics of Christianity; large increases in the developing world have been accompanied by substantial declines in the developed world, mainly in Europe and North America.<ref>Ustorf. "A missiological postscript", p. 219f.</ref> It is still the predominant religion in [[Europe]], the [[Americas]], the [[Philippines]], and [[Southern Africa]].<ref>[http://www.britannica.com/eb/table?tocId=9394911 Encyclopedia Britannica] table of religions, by region; retrieved November 2007</ref> However it is declining in some areas including [[Oceania]] (Australia and [[New Zealand]]), [[Northern Europe]] (including [[Great Britain]],<ref>[http://www.ekklesia.co.uk/news/uk/061223/christendom New UK opinion poll shows continuing collapse of 'Christendom']</ref> [[Scandinavia]] and other places), France, Germany, the Canadian provinces of [[Ontario]], [[British Columbia]], and [[Quebec]], the [[Western United States|Western]] and [[Northern United States|Northern]] portions of the United States, and parts of [[Asia]] (especially the [[Middle East]]<ref>Barrett/Kurian.''World Christian Encyclopedia'', p. 139 (Britain), 281 (France), 299 (Germany).</ref>,<ref>[http://news.bbc.co.uk/2/hi/middle_east/4499668.stm BBC NEWS - Guide: Christians in the Middle East]</ref><ref>[http://www.chron.com/disp/story.mpl/world/4425100.html Is Christianity dying in the birthplace of Jesus?]</ref> [[South Korea]],<ref>[http://www.omf.org/omf/uk/about_asia/countries/korea/south_korea_profile Number of Christians among young Koreans decreases by 5% per year]</ref> [[Taiwan]]<ref>[http://americanbuddhist.net/christianity-fading-taiwan Christianity fading in Taiwan | American Buddhist Net]</ref> and [[Macau]]<ref>[http://www.nytimes.com/2007/12/26/world/asia/26macao.html?_r=1&oref=slogin A Gambling-Fueled Boom Adds to a Church’s Bane]</ref>).

In most countries in the developed world, church attendance among people who continue to identify themselves as Christians has been falling over the last few decades.<ref>Putnam, ''Democracies in Flux: The Evolution of Social Capital in Contemporary Society'', p. 408.</ref> Some sources view this simply as part of a drift away from traditional membership institutions<ref>McGrath, ''Christianity: An Introduction'', p. xvi.</ref>, while others link it to signs of a decline in belief in the importance of religion in general.<ref>Peter Marber, ''Money Changes Everything: How Global Prosperity Is Reshaping Our Needs, Values and Lifestyles'', p. 99.</ref>

==Denominations==
{{main|Christian denomination}}

There is a diversity of [[doctrine]]s and practices among groups calling themselves Christian. These groups are sometimes classified under [[Christian denomination|denomination]]s, though for theological reasons many groups reject this classification system.<ref>Sydney E. Ahlstrom ({{Clarifyme|date=August 2008}}, p. 381.) characterized [[denominationalism]] in America as "a virtual ecclesiology" that "first of all repudiates the insistences of the Roman Catholic church, the churches of the 'magisterial' Reformation, and of most sects that they alone are the true Church." For specific citations, on the Roman Catholic Church see the ''Catechism of the Catholic Church'' §816; other examples: Donald Nash, [http://www.crownhillchurch.com/Why_the_Churches_of_Christ_Are_Not_A_Denomination.pdf#search=%22church%20of%20christ%20not%20a%20denomination%22 Why the Churches of Christ are not a Denomination]; Wendell Winkler, [http://www.thebible.net/introchurch/ch4.html Christ's Church is not a Denomination]; and David E. Pratt, [http://www.biblestudylessons.com/cgi-bin/gospel_way/denominations.php What does God think about many Christian denominations?]</ref>
Christianity may be broadly represented as being [[Schism (religion)|divided]] into five main groupings: Roman Catholicism, Eastern Orthodoxy, Oriental Orthodoxy, Protestantism and Restorationism.<ref name="North Virgina College - Four Sects">{{cite web|url = http://www.nvcc.edu/home/lshulman/Rel232/resource/Xiandivision.htm| title = Divisions of Christianity|publisher = North Virginia College|accessdate = 2007-12-31}}</ref><ref name="Religious Tolerance - Four Sects">{{cite web|url = http://www.religioustolerance.org/ldswho.htm| title = The LDS Restorationist movement,
including Mormon denominations|publisher = Religious Tolerance|accessdate = 2007-12-31}}</ref>

{{Denominations of Christianity}}
[[Image:ChristianityBranches.svg|500px|thumb|left|A simplified chart of historical developments of major groups within Christianity.]]

{{clear}}

===Roman Catholicism and other Catholic groups===
{{main|Roman Catholic Church}}

The [[Roman Catholic Church|(Roman) Catholic Church]] is comprised of those [[Particular Church|particular churches]], headed by bishops, in communion with the [[Pope]], the Bishop of Rome, as its highest authority in matters of faith, morality and Church governance.<ref name="LumenG">[[Second Vatican Council]], ''[http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en.html Lumen Gentium]''.</ref><ref name="SandSp1">Duffy, ''Saints and Sinners'', p. 1.</ref> Like the [[Eastern Orthodox]], the Roman Catholic Church through [[Apostolic succession]] traces its origins to the Christian community founded by Jesus Christ.<ref name="NatGeographic281">Hitchcock, ''Geography of Religion'', p. 281.</ref><ref name="Norman11">Norman, ''The Roman Catholic Church an Illustrated History'', p. 11, 14.</ref> Catholics maintain that the "[[Four Marks of the Church|one, holy, catholic and apostolic church]]" founded by Jesus [["Subsistit in" in Lumen Gentium|subsists fully]] in the Roman Catholic Church, but also acknowledges other Christian churches and communities<ref name = "LumenGentium">[[Second Vatican Council]], ''[http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19641121_lumen-gentium_en.html Lumen Gentium], chapter 2, paragraph 15.</ref><ref>[[Catechism of the Catholic Church]], [http://www.vatican.va/archive/catechism/p123a9p3.htm#IV paragraph 865].</ref> and works towards [[ecumenism|reconciliation]] among all Christians.<ref name = "LumenGentium"/> The Roman Catholic faith is detailed in the ''[[Catechism of the Catholic Church]]''.<ref name="cat">Marthaler, ''Introducing the Catechism of the Catholic Church, Traditional Themes and Contemporary Issues'' (1994), preface.</ref><ref>{{cite web | last = John Paul II| first =Pope | title =Laetamur Magnopere | publisher =Vatican | year =1997 | url =http://www.usccb.org/catechism/text/laetamurmagnopere.htm | accessdate =2008-03-09 }}</ref>

The 2,782 [[Episcopal see|sees]]<ref>''[[Annuario Pontificio]]'' (2007), p. 1172.</ref> are grouped into 23 [[Particular Church|particular rites]], the largest being the [[Latin Rite]], each with distinct traditions regarding the [[liturgy]] and the administering the [[Sacraments of the Catholic Church|sacraments]].<ref name="OneFaith71">Barry, ''One Faith, One Lord'' (2001), p. 71</ref> With more than one billion baptized members, the Roman Catholic Church is the largest [[Ecclesia (church)|church]] representing over half of all Christians and one sixth of the [[world population|world's population]].<ref name="Adherents">Adherents.com, [http://www.adherents.com/Religions_By_Adherents.html ''Religions by Adherents'']</ref><ref>''Zenit.org'', "[http://www.zenit.org/article-18894?l=english Number of Catholics and Priests Rises]", 12 February 2007.</ref><ref name="CIA">[[Central Intelligence Agency]], ''[[https://www.cia.gov/library/publications/the-world-factbook/geos/xx.html#People CIA World Factbook]]'' (2007).</ref>

Various smaller communities, such as the [[Old Catholic Church|Old Catholic]] and [[Independent Catholic Churches]], include the word ''Catholic'' in their title, and share much in common with Roman Catholicism but are no longer in [[Communion (Christian)|communion]] with the [[Holy See|See of Rome]]. The [[Old Catholic Church]] is in communion with the [[Anglican Communion]].<ref>According to the Bonn Accord of 1931, cited at [http://www.churchofthebeatitudes.org/id19.html Old Catholic Church of the Beatitudes].</ref><ref>[http://www.caecg.de/ Council of Anglican Episcopal Churches in Germany].</ref>

===Eastern Orthodoxy===
{{main|Eastern Orthodox Church}}

[[Eastern Orthodox Church|Eastern Orthodoxy]] is comprised of those churches in communion with the Patriarchal Sees of the East, such as the [[Ecumenical Patriarch of Constantinople]].<ref name="ODCC1199">Cross/Livingstone. ''The Oxford Dictionary of the Christian Church'', p. 1199.</ref> Like the Roman Catholic Church, the Eastern Orthodox Church also traces its heritage to the foundation of Christianity through [[Apostolic succession]] and has an [[Episcopal polity|episcopal]] structure, though the [[autocephaly|autonomy]] of the individual, mostly national churches is emphasized. A number of conflicts with Western Christianity over questions of doctrine and authority culminated in the [[East-West Schism|Great Schism]]. Eastern Orthodoxy is the second largest single denomination in Christianity, with over 200 million adherents.<ref name="Adherents"/>

===Oriental Orthodoxy===

The [[Oriental Orthodox Church]]es (also called ''Old Oriental Churches'') are those eastern churches that recognize the first three ecumenical councils — [[First Council of Nicaea|Nicaea]], [[First Council of Constantinople|Constantinople]] and [[Council of Ephesus|Ephesus]] — but reject the dogmatic definitions of the [[Council of Chalcedon]] and instead espouse a [[Miaphysite]] christology.

===Protestantism===

In the 16th century, [[Martin Luther]], [[Huldrych Zwingli]], and [[John Calvin]] inaugurated what has come to be called [[Protestantism]]. Luther's primary theological heirs are known as [[Lutheranism|Lutherans]]. Zwingli and Calvin's heirs are far broader denominationally, and are broadly referred to as the [[Reformed|Reformed Tradition]].<ref name="McManners251">McManners, ''Oxford Illustrated History of Christianity''. p. 251-259.</ref> Most Protestant traditions branch out from the Reformed tradition in some way. In addition to the Lutheran and Reformed branches of the Reformation, there is [[Anglicanism]] after the [[English Reformation]]. The [[Anabaptist]] tradition was largely ostracized by the other Protestant parties at the time, but has achieved a measure of affirmation in more recent history.

The oldest Protestant groups separated from the Roman Catholic Church in the 16th century [[Protestant Reformation]], followed in many cases by further divisions.<ref name="McManners251"/> For example, the [[Methodist Church]] grew out of Anglican minister [[John Wesley]]'s [[Evangelism|evangelical]] and [[Holiness Movement|revival movement]] in the [[Anglican Church]].<ref name="Methodist Central Hall Westminster - Methodism">{{cite web|url = http://www.methodist-central-hall.org.uk/history/WhatisMethodism.htm| title = About The Methodist Church|publisher = Methodist Central Hall Westminster|accessdate = 2007-12-31}}</ref><ref name="Public Service Projects - Holiness Movement">{{cite web|url = http://mb-soft.com/believe/text/holiness.htm| title = American Holiness Movement|publisher = Finding Your Way, Inc.|accessdate = 2007-12-31}}</ref> Several [[Pentecostal]] and non-denominational Churches, which emphasize the cleansing power of the [[Holy Spirit]], in turn grew out of the [[Methodist Church]].<ref name="FYW - Pentecostalism">{{cite web|url = http://www.findingyourwayinc.org/christianity.htm| title = Christianity: Pentecostal Churches|publisher = Finding Your Way, Inc.|accessdate = 2007-12-31}}</ref><ref name="Public Service Projects - Holiness Movement" /> Because Methodists, Pentecostals, and other [[evangelicals]] stress "accepting Jesus as your personal Lord and Savior"<ref name="CUMC Accepting Christ">{{cite web|url = http://www.cambridgechristumc.com/statementofbelief.htm| title = Statement of Belief|publisher = Cambridge Christ United Methodist Church|accessdate = 2007-12-31}}</ref>, which comes from [[John Wesley]]'s emphasis of the [[New Birth]]<ref name="UMC GBGM-The New Birth">{{cite web|url = http://new.gbgm-umc.org/umhistory/wesley/sermons/45/| title = The New Birth by John Wesley (Sermon 45)|publisher = The United Methodist Church GBGM|accessdate = 2007-12-31}}</ref>, they often refer to themselves as being [[Born again Christianity|born-again]].<ref name="UMC GBGM-Grace">{{cite web|url = http://gbgm-umc.org/umw/wesley/walk.stm| title = God's Preparing, Accepting, and Sustaining Grace|publisher = The United Methodist Church GBGM|accessdate = 2007-12-31}}</ref><ref name="Warren Wilson College - Total Experience of the Spirit">{{cite web|url = http://www.warren-wilson.edu/~religion/newifo/religions/christianity/index/pentecostal/essay.shtml| title = Total Experience of the Spirtit|publisher = Warren Wilson College|accessdate = 2007-12-31}}</ref>

Estimates of the total number of Protestants are very uncertain, partly because of the difficulty in determining which denominations should be placed in these categories, but it seems clear that Protestantism is the second largest major group of Christians after Roman Catholicism in number of followers (although the Eastern Orthodox Church is larger than any single Protestant denomination).<ref name="Adherents" />

A special grouping are the [[Anglicanism|Anglican churches]] descended from the [[Church of England]] and organised in the [[Anglican Communion]].. Some Anglican churches consider themselves both Protestant and Catholic.<ref>Sykes/Booty/Knight. ''The Study of Anglicanism'', p. 219.</ref> Some Anglicans consider their church a [[Branch theory|branch of the "One Holy Catholic Church"]] alongside of the Roman Catholic and Eastern Orthodox Churches, a concept rejected by the Roman Catholic Church and some Eastern Orthodox.<ref>Gregory Hallam, ''[http://www.orthodoxresearchinstitute.org/articles/ecumenical/hallam_orthodoxy_ecumenism.htm Orthodoxy and Ecumenism]''.</ref><ref>Gregory Mathewes-Green, "[http://www.westernorthodox.com/branch.html Whither the Branch Theory?]", ''Anglican Orthodox Pilgrim'' Vol. 2, No. 4.</ref>

Some Christians who come out of the Protestant tradition identify themselves simply as "Christian", or "[[born-again]] Christian"; they typically distance themselves from the [[confessionalism (religion)|confessionalism]] and/or [[creed]]alism of other Christian communities<ref>Confessionalism is a term employed by historians to describe "the creation of fixed identities and systems of beliefs for separate churches which had previously been more fluid in their self-understanding, and which had not begun by seeking separate identities for themselves — they had wanted to be truly Catholic and reformed." (MacCulloch, ''The Reformation: A History'', p. xxiv.)</ref> by calling themselves "[[Non-denominational Christianity|non-denominational]]" — often founded by individual pastors, they have little affiliation with historic denominations.

===Restorationism===

[[Restorationism]] is composed of various unrelated churches that believe they are restoring the original church of Jesus Christ and not reforming any of the churches existing at the time of their perceived restorations.<ref>McManners, ''Oxford Illustrated History of Christianity'', p. 91f.</ref> They teach that the other divisions of Christianity have introduced defects into Christianity, which is known as the [[Great Apostasy]].<ref name="Religious Tolerance - Restorationism">{{cite web|url = http://www.religioustolerance.org/chrrest.htm| title = The Restorationist Movements|publisher = Religious Tolerance|accessdate = 2007-12-31}}</ref><ref name="Got Questions Ministries - Restorationism">{{cite web|url = http://www.gotquestions.org/restorationism.html| title = What is Restorationism?|publisher = Got Questions Ministries|accessdate = 2007-12-31}}</ref> Some of these are historically connected to early-19th century camp meetings in the Midwest and Upstate New York. American [[Millennialism]] and [[Adventist|Adventism]], which arose from Evangelical Protestantism, produced the [[Jehovah's Witnesses]] movement (with 6.6 million members<ref>JW-Media.org [http://www.jw-media.org/people/statistics.htm#Jehovah%Witness%Membership%2005 Membership 2005]</ref>), and, as a reaction specifically to [[William Miller]], [[Seventh-day Adventist Church|Seventh-day Adventists]]. Additionally, there are the following groups: [[Christadelphians]], [[Churches of Christ]] with 2.6 million members, [[Disciples of Christ]] with 800,000 members,<ref> ''Statistical Report: Annual Council of the General Conference Committee Silver Spring, Marlyand, 6 October—11, 2006''</ref> and [[The Church of Jesus Christ of Latter-day Saints]], the largest denomination of the [[Latter Day Saint movement]] with over 13 million members. Though Restorationists have some superficial similarities, their doctrine and practices vary significantly.

[[Mainstream]] Christianity is widely used to refer collectively to the common views of major denominations of Christianity (such as [[Roman Catholicism]], [[Protestantism]], [[Anglicanism]], [[Orthodox Christianity]]) as against the particular tenets of other sects or [[Christian denomination]]. The context is dependent on the particular issues addressed, but usually contrasts the [[orthodox]] majority view against [[heterodox]] minority views of groups like Restorationists. In the most common sense, "mainstream" refers to [[Nicene Christianity]], or rather the traditions which continue to claim adherence to the [[Nicene Creed]].<ref>
{{cite web | last = | first = | authorlink = | coauthors = | title =Nicene Creed | work =Encyclopædia Britannica Online | publisher =Encyclopædia Britannica |date=2007 | url =http://www.britannica.com/eb/article-9055702 | format = | doi = | accessdate =2007-12-31}}</ref>

==Ecumenism==
{{main|Ecumenism}}

Most churches have long expressed ideals of being reconciled with each other, and in the 20th century Christian [[ecumenism]] advanced in two ways.<ref name="McManners581">McManners, ''Oxford Illustrated History of Christianity'', p. 581-584.</ref> One way was greater cooperation between groups, such as the [[Edinburgh Missionary Conference]] of Protestants in 1910, the Justice, Peace and Creation Commission of the [[World Council of Churches]] founded in 1948 by Protestant and Orthodox churches, and similar national councils like the [[National Council of Churches in Australia]] which includes Roman Catholics.<ref name="McManners581"/>

The other way was institutional union with new [[United and uniting churches]]. [[Congregational church|Congregationalist]], [[Methodist]], and [[Presbyterian]] churches united in 1925 to form the [[United Church of Canada]],<ref>McManners, ''Oxford Illustrated History of Christianity''. p. 413f.</ref> and in 1977 to form the [[Uniting Church in Australia]]. The [[Church of South India]] was formed in 1947 by the union of [[Anglicanism|Anglican]], [[Methodism|Methodist]], [[Congregational church|Congregationalist]], [[Presbyterianism|Presbyterian]], and [[Reformed Church|Reformed]] churches.<ref>McManners, ''Oxford Illustrated History of Christianity'', p. 498.</ref>

Steps towards reconciliation on a global level were taken in 1965 by the Roman Catholic and Orthodox churches mutually revoking the excommunications that marked their [[East-West Schism|Great Schism]] in 1054;<ref>McManners, ''Oxford Illustrated History of Christianity'', p. 373.</ref> the [[Anglican Roman Catholic International Commission]] (ARCIC) working towards full communion between those churches since 1970;<ref>McManners, ''Oxford Illustrated History of Christianity'', p. 583.</ref> and the [[Lutheran World Federation|Lutheran]] and [[Roman Catholic Church|Roman Catholic]] churches signing The [[Joint Declaration on the Doctrine of Justification]] in 1999 to address conflicts at the root of the [[Protestant Reformation]]. In 2006 the [[World Methodist Council|Methodist church]] adopted the declaration.<ref>[http://www.lutheranworld.org/What_We_Do/OEA/Methodist-Statement-2006-EN.pdf Methodist Statement]</ref>

==See also==
{{Christianityportal}}
*[[Freedom of religion]]
*[[Criticism of Christianity]]
*[[Good news (Christianity)]], concerning the gospel message of Christianity

==Notes==

{{reflist|2}}

==References==
;General refence:

*''American Heritage Dictionary of the English Language'', Houghton Mifflin Company (2006).
*''Catechism of the Catholic Church''.{{Clarifyme|date=August 2008}}
*''Columbia Electronic Encyclopedia''.{{Clarifyme|date=August 2008}}
*''Encyclopedia of Religion''.{{Clarifyme|date=August 2008}}
*''New Dictionary of Cultural Literacy''.{{Clarifyme|date=August 2008}}
*''New Dictionary of Theology''.{{Clarifyme|date=August 2008}}
*Barrett, David; Kurian, Tom et al. (ed.). ''World Christian Encyclopedia''. Oxford University Press (2001).

;Monographies and articles:

*Ahlstrom, Sydney E. {{Clarifyme|date=August 2008}}
*Albright, William F. ''From the Stone Age to Christianity''.{{Clarifyme|date=August 2008}}
*Alexander, T. Desmond. ''New Dictionary of Biblical Theology''.{{Clarifyme|date=August 2008}}
*Anidjar, 2001.{{Clarifyme|date=August 2008}}
*[[Greg Bahnsen|Bahnsen, Greg]]. ''[http://www.cmfnow.com/articles/pt173.htm A Reformed Confession Regarding Hermeneutics'' (article 6)].

*Balge, Richard D. ''[http://www.wlsessays.net/subjects/IJ/ijsubind.htm#Justification Martin Luther, Augustinian]''.{{Clarifyme|date=August 2008}}
*Ball, Bryan; Johnsson, William (ed.). ''The Essential Jesus''. Pacific Press (2002). ISBN 0816319294.
*Barry, John F. ''One Faith, One Lord: A Study of Basic Catholic Belief''. William H. Sadlier (2001). ISBN 0-8215-2207-8
*Bettenson, Henry (ed.). ''Documents of the Christian Church''. Oxford University Press (1943).
*Bokenkotter, Thomas. ''A Concise History of the Catholic Church ''. Doubleday (2004). ISBN 0385505841
*Bruce, F.F. ''The Canon of Scripture''.{{Clarifyme|date=August 2008}}
*Chambers, Mortimer; Crew, Herlihy, Rabb, Woloch. ''The Western Experience. Volume II: The Early Modern Period''. Alfred A. Knopf (1974). ISBN 0-394-31734-3.
*Coffey, John. ''Persecution and Toleration in Protestant England 1558-1689''. Pearson Education (2000).
*Cross, F. L.; Livingstone, E. A. (ed.). ''The Oxford Dictionary of the Christian Church''. Oxford University Press (1997). ISBN 019211655X.{{Clarifyme|date=August 2008}}
*Deppermann, Klaus. ''Melchior Hoffman: Social Unrest and Apocalyptic Vision in the Age of Reformation''. ISBN 0-567-08654-2.{{Clarifyme|date=August 2008}}
*Dilasser, Maurice. ''The Symbols of the Church''. Collegeville, MN: Liturgical Press (1999). ISBN 0-8146-2538-X
*Duffy, Eamon. ''Saints and Sinners, a History of the Popes''. Yale University Press (1997). ISBN 0-3000-7332-1
*Elwell, Walter A.; Comfort, Philip Wesley. ''Tyndale Bible Dictionary'', Tyndale House Publishers (2001). ISBN 0842370897.
*Esler, Phillip F. ''The Early Christian World''. Routledge (2004).
*Farrar, F.W. ''[http://www.tentmaker.org/books/mercyandjudgment/mercy_and_judgment_ch1.html Mercy and Judgment. A Few Last Words On Christian Eschatology With Reference to Dr. Pusey's, "What Is Of Faith?"]''. Macmillan, London/New York (1904).
*Foutz, Scott. ''[http://www.quodlibet.net/luther.shtml '' Martin Luther and Scripture]'' Martin Luther and Scripture''.{{Clarifyme|date=August 2008}}

*Fowler, Jeaneane D. ''World Religions: An Introduction for Students'', Sussex Academic Press (1997). ISBN 1898723486.
*[[Reginald H. Fuller|Fuller, Reginald H.]] ''[[Reginald H. Fuller#The Foundations of New Testament Christology (1965)|The Foundations of New Testament Christology]]'' Scribners (1965). ISBN 068415532X.
*Froehle, Bryan; Gautier, Mary, ''Global Catholicism, Portrait of a World Church'', Orbis books; Center for Applied Research in the Apostolate, Georgetown University (2003) ISBN=157075375x
*Funk, Robert. ''The Acts of Jesus: What Did Jesus Really Do?''. Polebridge Press (1998). ISBN 0060629789.
*Glenny, W. Edward. ''Typology: A Summary Of The Present Evangelical Discussion''.
*Gonzalez, Justo L. ''The Story of Christianity: The Early Church to the Dawn of the Reformation'', Harper Collins Publishers, New York (1984).
*Hanegraaff, Hank. ''Resurrection: The Capstone in the Arch of Christianity''. Thomas Nelson (2000). IBSN 0849916437.
*Harnack, Adolf von. ''[http://www.ccel.org/ccel/harnack/dogma1.ii.iii.iii.html History of Dogma]'' (1894).{{Clarifyme|date=August 2008}}
*Hickman, Hoyt L. et al. ''Handbook of the Christian Year''. Abingdon Press (1986). ISBN 0-687-16575-X
*Hinnells, John R. ''The Routledge Companion to the Study of Religion'' (2005).{{Clarifyme|date=August 2008}}
*Hitchcock, Susan Tyler. ''Geography of Religion''. [[National Geographic Society]] (2004) ISBN 0-7922-7313-3
*Kelly, J.N.D. ''Early Christian Doctrines''.{{Clarifyme|date=August 2008}}
*Kelly, J.N.D. ''The Athanasian Creed''. Harper & Row, New York (1964).
*Kirsch, Jonathan. ''God Against the Gods''.{{Clarifyme|date=August 2008}}
*Kreeft, Peter. ''Catholic Christianity''. Ignatius Press (2001) ISBN 0-89870-798-6
*Letham, Robert. ''The Holy Trinity in Scripture, History, Theology, and Worship''. P & R Publishing (2005). ISBN 0875520006.
*Lorenzen, Thorwald. ''Resurrection, Discipleship, Justice: Affirming the Resurrection Jesus Christ Today''. Smyth & Helwys (2003). ISBN 1573123994.
*McLaughlin, R. Emmet, ''Caspar Schwenckfeld, reluctant radical: his life to 1540'', New Haven: Yale University Press (1986). ISBN 0-300-03367-2.
*MacCulloch, Diarmaid, ''The Reformation: A History''. Viking Adult (2004).
*Marber, Peter. ''Money Changes Everything: How Global Prosperity Is Reshaping Our Needs, Values and Lifestyles''. FT Press (2003). ISBN 0130654809
*Marthaler, Berard. ''Introducing the Catechism of the Catholic Church, Traditional Themes and Contemporary Issues''. Paulist Press (1994). ISBN 0809134950
*Mathison, Keith. ''The Shape of Sola Scriptura'' (2001).{{Clarifyme|date=August 2008}}
*McClintock, John, ''Cyclopaedia of Biblical, Theological, and Ecclesiastical Literature''. Harper &Brothers, original from Harvard University (1889)
*McGrath, Alister E. ''Christianity: An Introduction''. Blackwell Publishing (2006). ISBN 1405108991.
*McGrath, Alister E. ''Historical Theology''.{{Clarifyme|date=August 2008}}
*McManners, John. ''Oxford Illustrated History of Christianity''. Oxford University Press (1990). IBSN 0198229283.
*Meconi, David Vincent. "Pagan Monotheism in Late Antiquity", in: ''Journal of Early Christian Studies''.{{Clarifyme|date=August 2008}}
*Metzger, Bruce M., Michael Coogan (ed.). ''Oxford Companion to the Bible''. Oxford University Press (1993). ISBN 0195046455.
*Norman, Edward. ''The Roman Catholic Church, An Illustrated History''. University of California (2007) ISBN 978-0-520-25251-6
*Olson, Roger E., ''The Mosaic of Christian Belief''. InterVarsity Press (2002). ISBN 9780830826957.
*Orlandis, Jose, ''A Short History of the Catholic Church''. Scepter Publishers (1993) ISBN 1851821252
*Ott, Ludwig. ''Grundriß der Dogmatik''. Herder, Freiburg (1965).{{Clarifyme|date=August 2008}}
*Pelikan, Jaroslav; Hotchkiss, Valerie (ed.) ''Creeds and Confessions of Faith in the Christian Tradition''. Yale University Press (2003). ISBN 0300093896.
*Putnam, Robert D. ''Democracies in Flux: The Evolution of Social Capital in Contemporary Society''. Oxford University Press (2002).
*Riley-Smith, Jonathan. ''The Oxford History of the Crusades''. New York: Oxford University Press, (1999).
*Robinson, George. ''Essential Judaism: A Complete Guide to Beliefs, Customs and Rituals''. New York: Pocket Books (2000).
*Schama, Simon . ''A History of Britain''. Hyperion (2000). ISBN 0-7868-6675-6.
*Servetus, Michael. ''Restoration of Christianity''. Lewiston, New York: Edwin Mellen Press (2007).
*Simon, Edith. ''Great Ages of Man: The Reformation''. Time-Life Books (1966). ISBN 0662278208.
*Smith, J.Z. (1998).{{Clarifyme|date=August 2008}}
*Spitz, Lewis. ''The Protestant Reformation''. Concordia Publishing House (2003). ISBN 0570033209.
*Sproul, R.C. ''Knowing Scripture''.{{Clarifyme|date=August 2008}}
*[[Charles Spurgeon|Spurgeon, Charles]]. ''[http://www.spurgeon.org/calvinis.htm A Defense of Calvinism]''.{{Clarifyme|date=August 2008}}
*Sykes, Stephen; Booty, John; Knight, Jonathan. ''The Study of Anglicanism''. Augsburg Fortress Publishers (1998). ISBN 080063151X.
*Talbott, Thomas. ''[http://www.willamette.edu/~ttalbott/PICTURES.pdf Three Pictures of God in Western Theology]" (1995).{{Clarifyme|date=August 2008}}

*Ustorf, Werner. "A missiological postscript", in: McLeod, Hugh; Ustorf, Werner (ed.). ''The Decline of Christendom in Western Europe, 1750-2000''. Cambridge University Press (2003).
*White, Howard A. ''[http://www.appiusforum.com/restoration.html The History of the Church]''.{{Clarifyme|date=August 2008}}
*Woodhead, Linda. ''An Introduction to Christianity''.{{Clarifyme|date=August 2008}}


==Further reading==

*{{cite book |author=Gill, Robin |title=The Cambridge companion to Christian ethics |publisher=Cambridge University Press |location=Cambridge, UK |year=2001 |pages= |isbn=0521779189 |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=Gunton, Colin E. |title=The Cambridge companion to Christian doctrine |publisher=Cambridge University Press |location=Cambridge, UK |year=1997 |pages= |isbn=0-521-47695-X |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=MacMullen, Ramsay |title=Voting About God in Early Church Councils|publisher=Yale University Press |location=New Haven, CT |year=2006 |pages= |isbn=0300115962 |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=Padgett, Alan G.; Sally Bruyneel |title=Introducing Christianity |publisher=Orbis Books |location=Maryknoll, N.Y. |year= 2003 |pages= |isbn= 1570753954 |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=Price, Matthew Arlen; Collins, Michael |title=The story of Christianity |publisher=Dorling Kindersley |location=New York |year=1999 |pages= |isbn=0-7513-0467-0 |oclc= |doi=}}
*{{cite book |author=[[Pope Benedict XVI|Ratzinger, Joseph]] |title=Introduction To Christianity (Communio Books) |publisher=Ignatius Press |location=San Francisco |year= 2004 |pages= |isbn=1586170295 |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=Tucker, Karen; Wainwright, Geoffrey|title=The Oxford history of Christian worship |publisher=Oxford University Press |location=Oxford [Oxfordshire] |year=2006 |pages= |isbn=0-19-513886-4 |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=Wagner, Richard |title=Christianity for Dummies |publisher=For Dummies |location= |year= 2004|pages= |isbn=0764544829 |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author= Webb, Jeffrey B. |title=The Complete Idiot's Guide to Christianity |publisher=Alpha Books |location=Indianapolis, Ind |year= 2004|pages= |isbn= 159257176X |oclc= |doi= |accessdate=2008-01-03}}
*{{cite book |author=Woodhead, Linda |title=Christianity: a very short introduction |publisher=Oxford University Press |location=Oxford [Oxfordshire] |year=2004 |pages= |isbn=0192803220 |oclc= |doi= |accessdate=2008-01-03}}

== External links ==
{{sisterlinks}}
*{{cite web |url=http://www.bbc.co.uk/religion/religions/christianity/index.shtml |title=BBC - Religion & Ethics - Christianity |accessdate=2008-01-03 |accessmonthday= |accessdaymonth= |accessyear= |author= |last= |first= |authorlink= |coauthors= |date= |year= |month= |format= |work= |publisher=British Broadcasting Corporation |pages= |doi= |archiveurl= |archivedate= |quote= }} A number of introductory articles on Christianity.

*{{cite web |url=http://www.cbc.ca/montreal/features/religion/christianity.html |title=CBC Montreal - Religion - Christianity |accessdate= 2008-01-03 |accessmonthday= |accessdaymonth= |accessyear= |author= |last= |first= |authorlink= |coauthors= |date= |year= |month= |format= |work= |publisher=Canadian Broadcasting Corporation |pages= |doi= |archiveurl= |archivedate= |quote= }} An overview of Christianity.

*{{cite web |url=http://www.netzarim.co.il |title=Netzarim |accessdate= 2008-10-21 |accessmonthday= |accessdaymonth= |accessyear= |author= |last= |first= |authorlink= |coauthors= |date= |year= |month= |format= |work= |publisher=- Click at 'History Museum' in the left menu |pages= |doi= |archiveurl= |archivedate= |quote= }} The origin of Christianity

{{Christianityfooter|uncollapsed}}
{{Religion topics}}

[[Category:Christianity| ]]
[[Category:Middle Eastern culture]]
[[Category:Western culture]]

{{Link FA|ja}}
{{Link FA|mk}}
{{Link FA|vi}}
[[af:Christendom]]
[[als:Christentum]]
[[am:ክርስትና]]
[[ang:Crīstendōm]]
[[ar:مسيحية]]
[[an:Cristianismo]]
[[arc:ܟܪܣܛܝܢܘܬܐ]]
[[roa-rup:Crishinizmo]]
[[frp:Cristianismo]]
[[ast:Cristianismu]]
[[az:Xristianlıq]]
[[bn:খ্রিস্ট ধর্ম]]
[[zh-min-nan:Ki-tok-kàu]]
[[ba:Христианлыҡ]]
[[be:Хрысціянства]]
[[be-x-old:Хрысьціянства]]
[[bcl:Kristianismo]]
[[bar:Kristndum]]
[[bs:Hrišćanstvo]]
[[br:Kristeniezh]]
[[bg:Християнство]]
[[ca:Cristianisme]]
[[cv:Христианлăх]]
[[ceb:Kristiyanismo]]
[[cs:Křesťanství]]
[[co:Cristianisimu]]
[[cy:Cristnogaeth]]
[[da:Kristendom]]
[[de:Christentum]]
[[dv:މަސީހީދީން]]
[[et:Kristlus]]
[[el:Χριστιανισμός]]
[[es:Cristianismo]]
[[eo:Kristanismo]]
[[eu:Kristautasun]]
[[fa:مسیحیت]]
[[fo:Kristindómur]]
[[fr:Christianisme]]
[[fy:Kristendom]]
[[fur:Cristianesim]]
[[ga:Críostaíocht]]
[[gd:Crìosdaidheachd]]
[[gl:Cristianismo]]
[[gan:基督教]]
[[zh-classical:基督教]]
[[hak:Kî-tuk-kau]]
[[ko:기독교]]
[[ha:Kiristancìì]]
[[hy:Քրիստոնեություն]]
[[hi:ईसाई धर्म]]
[[hsb:Křesćanstwo]]
[[hr:Kršćanstvo]]
[[io:Kristanismo]]
[[ig:Christianity]]
[[ilo:Cristianidad]]
[[id:Kekristenan]]
[[ia:Christianismo]]
[[ie:Cristianisme]]
[[os:Чырыстон дин]]
[[zu:Ubukrestu]]
[[is:Kristni]]
[[it:Cristianesimo]]
[[he:נצרות]]
[[jv:Kristen]]
[[kn:ಕ್ರೈಸ್ತ ಧರ್ಮ]]
[[ka:ქრისტიანობა]]
[[kk:Мәсіхшілік]]
[[kw:Kristoneth]]
[[rw:Kristendomu]]
[[ky:Машаякчылык]]
[[sw:Ukristo]]
[[kg:Kiyesu]]
[[ht:Krisyanis]]
[[ku:Xirîstiyanî]]
[[la:Religio Christiana]]
[[lv:Kristietība]]
[[lb:Chrëschtentum]]
[[lt:Krikščionybė]]
[[lij:Crestianeximo]]
[[li:Christendóm]]
[[ln:Boklísto]]
[[jbo:xi'ojda]]
[[hu:Kereszténység]]
[[mk:Христијанство]]
[[ml:ക്രിസ്തുമതം]]
[[mt:Kristjaneżmu]]
[[mi:Whakapono Karaitiana]]
[[mr:ख्रिश्चन धर्म]]
[[mzn:Messiavar / مسیحا وار]]
[[ms:Kristian]]
[[cdo:Gĭ-dók-gáu]]
[[mn:Христийн шашин]]
[[my:ခရစ်ယာန်ဘာသာ]]
[[nah:Quīxtianayōtl]]
[[nl:Christendom]]
[[nds-nl:Christendom]]
[[ja:キリスト教]]
[[pih:Kreschenitii]]
[[no:Kristendom]]
[[nn:Kristendommen]]
[[nrm:Chrêtchienneté]]
[[oc:Cristianisme]]
[[uz:Masihiylik]]
[[pa:ਈਸਾਈ ਦੀਨ]]
[[ps:عيسويت]]
[[pms:Cristianésim]]
[[nds:Christendom]]
[[pl:Chrześcijaństwo]]
[[pt:Cristianismo]]
[[crh:Hristianlıq]]
[[ro:Creştinism]]
[[qu:Kristiyanu iñiy]]
[[ru:Христианство]]
[[sco:Christianity]]
[[sq:Krishterimi]]
[[scn:Cristianèsimu]]
[[si:කිතු දහම]]
[[simple:Christianity]]
[[sk:Kresťanstvo]]
[[cu:Хрїстїаньство]]
[[sl:Krščanstvo]]
[[so:Masiixiyad]]
[[sr:Хришћанство]]
[[sh:Hrišćanstvo]]
[[fi:Kristinusko]]
[[szl:Chřeśćijaństwo]]
[[sv:Kristendom]]
[[tl:Kristiyanismo]]
[[ta:கிறிஸ்தவம்]]
[[kab:Tamasiḥit]]
[[tt:Христианлык]]
[[th:คริสต์ศาสนา]]
[[vi:Kitô giáo]]
[[tg:Дини Насронӣ]]
[[tpi:Kristen]]
[[tr:Hıristiyanlık]]
[[uk:Християнство]]
[[ur:عیسائیت]]
[[vec:Cristianèximo]]
[[wa:Crustinnisse]]
[[vls:Christndom]]
[[yi:קריסטנטום]]
[[yo:Ẹ̀sìn Kristi]]
[[zh-yue:基督敎]]
[[cbk-zam:Cristianismo]]
[[diq:İsewitine]]
[[bat-smg:Krėkštiuonībė]]
[[zh:基督教]]

Dinosaur

2008-10-22T22:40:39Z

ReaganFan0101:

{{otheruses}}
{{pp-semi-protected|small=yes}}
{{Taxobox
|name = Dinosaurs
|fossil_range = {{Fossil range|235|65|earliest=Late Triassic|latest=0|PS= Descendant taxon [[Aves]] survives to present.}}
|image = field_dinos_2.jpg
|image_width = 260px
|image_caption = Mounted skeletons of ''[[Tyrannosaurus]]'' (left) and ''[[Apatosaurus]]'' (right) at the [[American Museum of Natural History]].
|regnum = [[Animal]]ia
|phylum = [[Chordate|Chordata]]
|subphylum = [[Vertebrate|Vertebrata]]
|classis = [[Reptile|Sauropsida]]
|subclassis = [[Diapsid]]a
|infraclassis = [[Archosauromorpha]]
|superordo = '''Dinosauria'''
|superordo_authority = [[Richard Owen|Owen]], 1842
|subdivision_ranks = [[Order (biology)|Orders]] and [[Order (biology)|suborders]]
|subdivision = <div>
* '''[[Ornithischia]]''' [[extinction|†]]
** [[Cerapoda]] [[extinction|†]]
** [[Thyreophora]] [[extinction|†]]
* '''[[Saurischia]]'''
** [[Sauropodomorpha]] [[extinction|†]]
** [[Theropoda]]
}}
'''Dinosaurs''' ([[Greek]] δεινόσαυρος, deinosauros) were the dominant [[vertebrate]] animals of [[Landform|terrestrial]] [[ecosystem]]s for over 160 million years, from the late [[Triassic]] [[Period (geology)| period]] (about 230 [[Annum|million years ago]]) to the end of the [[Cretaceous]] [[Period (geology)| period]] (65 million years ago), when most of them became extinct in the [[Cretaceous–Tertiary extinction event]]. The 10,000 living species of [[birds]] have been [[cladistic|classified]] as dinosaurs.

The discovery in 1861 of ''[[Archaeopteryx]]'' first suggested a close relationship between dinosaurs and birds; aside from the presence of fossilized feather impressions, ''Archaeopteryx'' was very similar to the contemporary small predatory dinosaur ''[[Compsognathus]]''. Research since the 1970s indicates that [[Theropoda|theropod]] dinosaurs are most likely the ancestors of [[bird]]s; in fact, most paleontologists regard birds as the only surviving dinosaurs and some believe dinosaurs and birds should be put together under one biological class.<ref>Bakker, R. T., Galton, P., 1974. Dinosaur monophyly and a new class of vertebrates. ''Nature'' 248:168-172.</ref> [[Crocodilians]] are the other surviving close relatives of dinosaurs, and both groups are members of the [[Archosauria]], a group of [[reptiles]] that first appeared in the very late [[Permian]] and became dominant in the mid-Triassic.

For about the first half of the 20th century, both scientists and the general public regarded dinosaurs as slow, unintelligent [[cold-blooded]] animals. However, the bulk of [[Dinosaur renaissance|research since the 1970s]] has supported the view that they were active animals with elevated metabolisms, and often with adaptations for social interactions. This change of view was strongly influenced by evidence of the descent of birds from theropod dinosaurs.

Since the first dinosaur [[fossil]]s were recognized in the early nineteenth century, mounted dinosaur skeletons have become major attractions at museums around the world. Dinosaurs have become a part of world culture and remain consistently popular among children and adults. They have been featured in best-selling books and films (notably ''[[Jurassic Park]]''), and new discoveries are regularly covered by the [[News media|media]].

The term "dinosaur" was first coined in 1842 by [[Sir Richard Owen]] and derives from [[Greek language|Greek]] ''δεινός'' (''deinos'') "terrible, powerful, wondrous" + ''σαῦρος'' (''sauros'') "lizard". It is sometimes used informally to describe other prehistoric reptiles, such as the [[pelycosaur]] ''[[Dimetrodon]]'', the winged [[pterosaur]]s, and the aquatic [[ichthyosaur]]s, [[plesiosaur]]s and [[mosasaur]]s, although none of these were dinosaurs.

==Description==
===Etymology===
The [[taxon]] '''Dinosauria''' was formally named in 1842 by [[English people|English]] [[palaeontology|palaeontologist]] [[Richard Owen]], who used it to refer to the "distinct tribe or sub-order of Saurian Reptiles" that were then being recognized in England and around the world.<ref>Owen, R. (1842). "Report on British Fossil Reptiles." Part II. Report of the British Association for the Advancement of Science, Plymouth, England.</ref> The term is derived from the [[Ancient Greek|Greek]] words δεινός (''deinos'' meaning "terrible", "powerful", or "wondrous") and σαύρα (''saura'' meaning "lizard" or "reptile").<ref>{{cite web
|url=http://www.perseus.tufts.edu/cgi-bin/lexindex?lookup=deino/s&lang=greek&doc=Perseus:text:1999.01.0169&formentry=0
|title=Liddell-Scott-Jones Lexicon of Classical Greek |accessdate=2008-08-05
}}</ref> Though the taxonomic name has often been interpreted as a reference to dinosaurs' teeth, claws, and other fearsome characteristics, Owen intended it merely to evoke their size and majesty.<ref name=FBS97>{{cite book|author=Farlow, J.O., and Brett-Surman, M.K.|date=1997|title=Preface. In: Farlow, J.O., and Brett-Surman, M.K. (eds.). ''The Complete Dinosaur.''|publisher=Indiana University Press|pages=ix-xi|isbn=0-253-33349-0}}</ref>

In colloquial English "dinosaur" is sometimes used to describe an obsolete or unsuccessful thing or person,<ref>{{cite web
|url=http://www.merriam-webster.com/dictionary/dinosaur
|title=dinosaur - Definition from the Merriam-Webster Online Dictionary
|accessdate=2008-08-05
}}</ref> despite the dinosaurs' 160 million year reign and the global abundance and diversity of their descendants, the birds. This usage became common while dinosaurs were regarded as cold-blooded and sluggish.

===Modern definition===
[[Image:Triceratops AMNH 01.jpg|right|thumb|225px|''[[Triceratops]]'' [[skeleton]] at the [[American Museum of Natural History]] in New York City.]]
Under [[phylogenetics|phylogenetic taxonomy]], dinosaurs are usually defined as all descendants of the most recent common ancestor of ''[[Triceratops]]'' and modern [[birds]].<ref name="Irmis07">{{cite journal|author=Irmis, Randall B.|date=2007|title=A reappraisal of the phylogeny of early dinosaurs|journal=The Palaeontological Association Newsletter|volume=65|pages=92–94|url=http://socrates.berkeley.edu/~irmisr/sylbrad.pdf|accessdate=2007-11-22}}</ref> It has also been suggested that Dinosauria be defined as all of the descendants of the most recent common ancestor of ''[[Megalosaurus]]'' and ''[[Iguanodon]]'', because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria.<ref name="olshevsky2000">Olshevsky, G. (2000). "An annotated checklist of dinosaur species by continent." ''Mesozoic Meanderings'', '''3''': 1–157</ref> Both definitions result in the same set of animals being defined as dinosaurs, including [[theropoda|theropods]] (mostly [[bipedalism|bipedal]] [[carnivore]]s), [[sauropodomorpha|sauropodomorph]]s (mostly large [[herbivore|herbivorous]] [[quadruped]]s with long necks and tails), [[ankylosauria]]ns (armored herbivorous quadrupeds), [[stegosauria]]ns (plated herbivorous quadrupeds), [[ceratopsia]]ns (herbivorous quadrupeds with horns and frills), and [[ornithopoda|ornithopods]] (bipedal or quadrupedal herbivores including "duck-bills"). These definitions are written to correspond with scientific conceptions of dinosaurs that predate the modern use of phylogenetics. The continuity of meaning is intended to prevent confusion about what the term "dinosaur" means.

There is an almost universal consensus among paleontologists that birds are the descendants of theropod dinosaurs. Using the strict [[cladistics|cladistical]] definition that all descendants of a single common ancestor must be included in a group for that group to be natural, birds ''are'' dinosaurs and dinosaurs are, therefore, not extinct. Birds are classified by most paleontologists as belonging to the subgroup [[Maniraptora]], which are [[Coelurosauria|coelurosaurs]], which are theropods, which are [[saurischia]]ns, which are dinosaurs.<ref name=KP04>Padian, K. (2004). Basal Avialae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria'' (second edition). University of California Press:Berkeley, 210–231. ISBN 0-520-24209-2.</ref>

From the point of view of cladistics, birds are dinosaurs, but in ordinary speech the word "dinosaur" does not include birds. Additionally, referring to dinosaurs that are not birds as "non-avian dinosaurs" is cumbersome. For clarity, this article will use "dinosaur" as a synonym for "non-avian dinosaur". The term "non-avian dinosaur" will be used for emphasis as needed. It is also technically correct to refer to dinosaurs as a distinct group under the older [[Linnaean classification]] system, which accepts [[paraphyletic]] taxa that exclude some descendants of a single common ancestor.

===General description===
[[Image:Stego fieldmuseum.jpg|right|thumb|225px|''[[Stegosaurus]]'' skeleton, [[Field Museum]], [[Chicago]].]]
Using one of the above definitions, dinosaurs (aside from birds) can be generally described as terrestrial [[archosaur]]ian [[reptile]]s with [[terrestrial locomotion#Stance|limbs held erect beneath the body]], that existed from the [[Late Triassic]] (first appearing in the [[Carnian]] [[faunal stage]]) to the [[Late Cretaceous]] (going extinct at the end of the [[Maastrichtian]]).<ref name=DFG97>{{cite book |last=Glut |first=Donald F. |authorlink=Donald F. Glut |title=Dinosaurs: The Encyclopedia |year=1997 |publisher=McFarland & Co |location=Jefferson, North Carolina |pages=40 |isbn=0-89950-917-7}}</ref> Many prehistoric animals are popularly conceived of as dinosaurs, such as ichthyosaurs, mosasaurs, plesiosaurs, pterosaurs, and ''[[Dimetrodon]]'', but are not classified scientifically as dinosaurs. Marine reptiles like ichthyosaurs, mosasaurs, and plesiosaurs were neither terrestrial nor archosaurs; pterosaurs were archosaurs but not terrestrial; and ''Dimetrodon'' was a [[Permian]] animal more closely related to mammals.<ref name=DL90>{{cite book |last=Lambert |first=David |coauthors=and the Diagram Group |title=The Dinosaur Data Book |year=1990 |publisher=Avon Books |location=New York |isbn=0-380-75896-3 |pages=288}}</ref> Dinosaurs were the dominant terrestrial vertebrates of the Mesozoic, especially the [[Jurassic]] and Cretaceous. Other groups of animals were restricted in size and niches; mammals, for example, rarely exceeded the size of a cat, and were generally rodent-sized carnivores of small prey.<ref name=MM97>{{cite book |last=Morales |first=Michael |editor=Farlow, James O.; and Brett-Surman, Michael K. (eds.) |title=The Complete Dinosaur |year=1997 |publisher=Indiana University Press |location=Bloomington |isbn=0-253-33349-0 |pages=607–624 |chapter=Nondinosaurian vertebrates of the Mesozoic }}</ref> One notable exception is ''[[Repenomamus|Repenomamus giganticus]]'', a [[triconodont]] weighing between {{kg to lb|12}} and {{kg to lb|14}} that is known to have eaten small dinosaurs like young ''[[Psittacosaurus]]''.<ref name=huetal2005>{{cite journal |author=Hu Yaoming |coauthors=Meng Jin; Wang Yuanqing; and Li Chuankui |year=2005 |title=Large Mesozoic mammals fed on dinosaurs |journal=Nature |volume=433 |pages=149–152|doi=10.1038/nature03102}}</ref>

Dinosaurs were an extremely varied group of animals; according to a 2006 study, over 500 dinosaur genera have been identified with certainty so far, and the total number of genera preserved in the fossil record has been estimated at around 1,850, nearly 75% of which remain to be discovered.<ref>{{cite journal|author=Wang, S.C., and Dodson, P. |date=2006|title=Estimating the Diversity of Dinosaurs|journal=Proceedings of the National Academy of Sciences USA|volume=103|issue=37|pages=13601–13605|pmid= 16954187|doi=10.1073/pnas.0606028103}}</ref> An earlier study predicted that about 3,400 dinosaur genera existed, including many which would not have been preserved in the fossil record.<ref name="russell1995">{{cite journal|author=Russell, Dale A.|date=1995|title=China and the lost worlds of the dinosaurian era|journal=Historical Biology|volume=10|pages=3–12}}</ref> As of September 17, 2008, 1,047 different species of dinosaurs have been named.<ref>[http://news.bbc.co.uk/2/hi/science/nature/7620621.stm Will the real dinosaurs stand up?], BBC, September 17, 2008</ref> Some were herbivorous, others carnivorous. Some dinosaurs were bipeds, some were quadrupeds, and others, such as ''[[Ammosaurus]]'' and ''[[Iguanodon]]'', could walk just as easily on two or four legs. Many had [[armour (zoology)|bony armor]], or cranial modifications like horns and crests. Although known for large size, many dinosaurs were human-sized or smaller. Dinosaur remains have been found on every continent on Earth, including [[Antarctica]].<ref name="MacLeod"/> No dinosaurs are known to have lived in marine or aerial habitats, although it is possible some feathered theropods were flyers.

===Distinguishing features===
While recent discoveries have made it more difficult to present a universally agreed-upon list of dinosaurs' distinguishing features, nearly all dinosaurs discovered so far share certain modifications to the ancestral [[archosaur]]ian skeleton. Although some later groups of dinosaurs featured further modified versions of these traits, they are considered typical across Dinosauria; the earliest dinosaurs had them and passed them on to all their descendants. Such common features across a taxonomic group are called [[synapomorphy|synapomorphies]].

Dinosaur synapomorphies include an elongated crest on the [[humerus]], or upper arm bone, to accommodate the attachment of [[clavipectoral triangle|deltopectoral]] muscles; a shelf at the rear of the [[ilium (bone)|ilium]], or main hip bone; a [[tibia]], or shin bone, featuring a broad lower edge and a flange pointing out and to the rear; and an ascending projection on the [[talus bone|astragalus]], one of the ankle bones, which secures it to the tibia.<ref name=MJB04>{{cite book |last=Benton |first=Michael J. |authorlink=Michael J. Benton |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.)|title=The Dinosauria |edition=2nd |year=2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=7–19 |chapter=Origin and relationships of Dinosauria}}</ref>

[[Image:Edmontonia dinosaur.png|190px|left|thumb|''[[Edmontonia]]'' was an "armored dinosaur" of the group [[Ankylosauria]].]]
A variety of other skeletal features were shared by many dinosaurs. However, because they were either common to other groups of [[archosaurs]] or were not present in all early dinosaurs, these features are not considered to be synapomorphies. For example, as [[diapsid]] reptiles, dinosaurs ancestrally had two pairs of [[temporal fenestra]]e (openings in the skull behind the eyes), and as members of the diapsid group Archosauria, had additional openings in the [[antorbital fenestra|snout]] and lower jaw.<ref name=TRHJ00>{{cite book|author=Holtz, Jr., T.R. |date=2000|title=Classification and evolution of the dinosaur groups. In: Paul, G.S. (ed.). ''The Scientific American Book of Dinosaurs.''|publisher=St. Martin's Press|pages=140–168|isbn=0-312-26226-4}}</ref> Additionally, several characteristics once thought to be synapomorphies are now known to have appeared before dinosaurs, or were absent in the earliest dinosaurs and independently evolved by different dinosaur groups. These include an elongated [[scapula]], or shoulder blade; a [[sacrum]] composed of three or more fused [[vertebra]]e (three are found in some other archosaurs, but only two are found in ''[[Herrerasaurus]]'');<ref name=MJB04/> and an [[acetabulum]], or hip socket, with a hole at the center of its inside surface (closed in ''[[Saturnalia (dinosaur)|Saturnalia]]'', for example).<ref name=LARB99>{{cite journal|author=Langer, M.C., Abdala, F., Richter, M., and Benton, M.J. |date=1999|title=A sauropodomorph dinosaur from the Upper Triassic (Carnian) of southern Brazil|journal=Comptes Rendus de l'Academie des Sciences, Paris: Sciences de la terre et des planètes|volume=329|pages=511–517}}</ref> Another difficulty of determining distinctly dinosaurian features is that early dinosaurs and other archosaurs from the Late Triassic are often poorly known and were similar in many ways; these animals have sometimes been misidentified in the literature.<ref name=NIP07>{{cite journal |last=Nesbitt |first=Sterling J. |coauthors=Irmis, Randall B.; and Parker, William G. |year=2007 |title=A critical re-evaluation of the Late Triassic dinosaur taxa of North America |journal=Journal of Systematic Palaeontology |volume=5 |issue=2 |pages=209–243 |doi=10.1017/S1477201907002040 }}</ref>

[[Image:Sprawling and erect hip joints - horiz.png| thumb | right | 300px | Hip joints and hindlimb postures.]]
Dinosaurs stood erect in a manner similar to [[Evolution of mammals#Erect limbs|most modern mammals]], but distinct from most other reptiles, whose limbs sprawl out to either side.<ref>This was recognized not later than 1909: {{cite web |title=Dr. Holland and the Sprawling Sauropods |url=http://www.hmnh.org/library/diplodocus/holland1910.html }} The arguments and many of the images are also presented in {{cite book |title=Hot Blooded Dinosaurs |author=Desmond, A. |publisher=DoubleDay |date=1976 |isbn=0385270631}}</ref> Their posture was due to the development of a laterally-facing recess in the pelvis (usually an open socket) and a corresponding inwardly-facing distinct head on the femur.<ref name=MJB00>{{cite book|author=Benton, M.J.|date=2004|title=Vertebrate Paleontology|publisher=Blackwell Publishers|pages=xii-452|isbn=0-632-05614-2}}</ref> Their erect posture enabled dinosaurs to breathe easily while moving, which likely permitted stamina and activity levels that [[Carrier's constraint|surpassed those of "sprawling" reptiles]].<ref name=RC05>{{cite book |last=Cowen |first=Richard |title=History of Life |edition=4th edition |chapter=Dinosaurs |publisher=Blackwell Publishing |isbn=1405117567 |pages=151–175 |year=2004 |oclc=53970577}}</ref> Erect limbs probably also helped support the evolution of large size by reducing bending stresses on limbs.<ref name=TKMB07>{{cite journal |last=Kubo |first=T. |coauthors=M.J. Benton |year=2007 |title=Evolution of hindlimb posture in archosaurs: limb stresses in extinct vertebrates |journal=Palaeontology |volume=50 |issue=6 |pages=1519–1529 |doi=10.1111/j.1475-4983.2007.00723.x}}</ref> Some non-dinosaurian archosaurs, including [[rauisuchia]]ns, also had erect limbs but achieved this by a "pillar erect" configuration of the hip joint, where instead of having a projection from the femur insert on a socket on the hip, the [[ilium (bone)|upper pelvic bone]] was rotated to form an overhanging shelf.<ref name=TKMB07/>

==Natural history==
===Origins and early evolution===
{{main|Evolution of dinosaurs}}
[[Image:Eopraptor sketch5.png|thumb|''[[Eoraptor]]'', an early dinosaur genus.]]
For a long time many scientists thought dinosaurs were [[polyphyletic]] with multiple groups of unrelated "dinosaurs" evolving due to similar pressures,<ref>{{cite journal |author=Seeley, H.G. |date=1887 |title=On the classification of the fossil animals commonly named Dinosauria |journal=Proc R Soc London |publisher=[[Royal Society]] |volume=43 |pages=165–171 }}</ref><ref>{{cite book |author=Romer, A.S. |date=1956 |title=Osteology of the Reptiles |publisher=University of Chicago }}</ref><ref name="Ostrom1980EvidenceOfEndothermyInDinosaurs">{{ citation |author=Ostrom, J.H. |date=1980 |chapter=The evidence of endothermy in dinosaurs |editor=Thomas, R.D.K. and Olson, E.C. |title=A cold look at the warm-blooded dinosaurs |pages=82–105 |publisher=American Association for the Advancement of Science |location=Boulder, CO |url=http://bio.fsu.edu/~amarquez/Evolutionary%20Morphology%20fall%202004/Ostrom/The%20evidence%20for%20endothermy%20in%20dinosaurs%20-%20Ostrom.pdf }}</ref> but dinosaurs are now known to have formed a single group.<ref>{{cite journal |date=1974 |title=Dinosaur monophyly and a new class of vertebrates |journal=Nature |volume=248 |pages=168–172 | doi=10.1038/248168a0 |url=http://www.nature.com/nature/journal/v248/n5444/abs/248168a0.html |author=Bakker, R. T., and Galton, P.}}</ref><ref name="MJB04" />

Dinosaurs diverged from their [[archosaur]] ancestors approximately 230 million years ago during the Middle to Late [[Triassic]] period, roughly 20 million years after the [[Permian-Triassic extinction event]] wiped out an estimated 95% of all [[life on Earth]].<ref>{{cite journal|author=Kump LR, Pavlov A & Arthur MA|title=Massive release of hydrogen sulfide to the surface ocean and atmosphere during intervals of oceanic anoxia|journal=Geology|date=2005|volume=33|issue=5|pages=397–400|doi=10.1130/G21295.1}}</ref><ref name="TannerLucas">{{cite journal|author=Tanner LH, Lucas SG & Chapman MG|title=Assessing the record and causes of Late Triassic extinctions|journal=Earth-Science Reviews|volume=65|issue=1-2|pages=103–139|date=2004|doi=10.1016/S0012-8252(03)00082-5|url=http://nmnaturalhistory.org/pdf_files/TJB.pdf|accessdate=2007-10-22}}</ref> [[Radiometric dating]] of the [[rock formation]] that contained fossils from the early dinosaur [[genus]] ''[[Eoraptor]]'' establishes its presence in the fossil record at this time. Paleontologists believe ''Eoraptor'' resembles the [[Common descent|common ancestor]] of all dinosaurs;<ref name="Sereno1999">{{cite journal|author=Sereno PC|title=The evolution of dinosaurs|date=1999|journal=Science|volume=284|issue=5423|pages=2137–2147|doi=10.1126/science.284.5423.2137|pmid=10381873}}</ref> if this is true, its traits suggest that the first dinosaurs were small, bipedal [[predation|predators]].<ref name=SFRM93>{{cite journal |last=Sereno |first=P.C. |authorlink=Paul Sereno |coauthors=Forster, C.A.; Rogers, R.R.; and Monetta, A.M. |year=1993 |title=Primitive dinosaur skeleton from Argentina and the early evolution of Dinosauria |journal=Nature |volume=361 |pages=64–66|doi=10.1038/361064a0}}</ref> The discovery of primitive, dinosaur-like [[ornithodiran]]s such as ''[[Marasuchus]]'' and ''[[Lagerpeton]]'' in [[Argentina|Argentinian]] [[Middle Triassic]] strata supports this view; analysis of recovered fossils suggests that these animals were indeed small, bipedal predators.

When dinosaurs appeared, terrestrial habitats were occupied by various types of basal archosaurs and [[therapsida|therapsids]], such as [[aetosaur]]s, [[cynodont]]s, [[dicynodont]]s, [[ornithosuchidae|ornithosuchid]]s, [[rauisuchia]]s, and [[rhynchosaur]]s. Most of these other animals became extinct in the Triassic, in one of two events. First, at about the boundary between the [[Carnian]] and [[Norian]] [[faunal stage]]s (about 215 million years ago), dicynodonts and a variety of basal [[archosauromorpha|archosauromorph]]s, including the [[prolacertiformes|prolacertiforms]] and rhynchosaurs, became extinct. This was followed by the [[Triassic-Jurassic extinction event]] (about 200 million years ago), that saw the end of most of the other groups of early archosaurs, like aetosaurs, ornithosuchids, [[phytosaur]]s, and rauisuchians. These losses left behind a land fauna of [[crocodylomorpha|crocodylomorph]]s, dinosaurs, [[mammal]]s, [[pterosauria]]ns, and [[turtle]]s.<ref name=MJB04/>

The first few lines of primitive dinosaurs [[Adaptive radiation|diversified]] through the [[Carnian]] and [[Norian]] [[faunal stage|stage]]s of the Triassic, most likely by occupying the niches of groups that became extinct. Traditionally, dinosaurs were thought to have [[Competition (biology)|replaced]] the variety of other Triassic land animals by proving superior through a long period of competition. This now appears unlikely, for several reasons. Dinosaurs do not show a pattern of steadily increasing in diversity and numbers, as would be predicted if they were competitively replacing other groups; instead, they were very rare through the Carnian, making up only 1-2% of individuals present in [[fauna]]s. In the Norian, however, after the extinction of several other groups, they became significant components of faunas, representing 50-90% of individuals. Also, what had been viewed as a key adaptation of dinosaurs, their erect stance, is now known to have present in several contemporaneous groups that were not as successful (aetosaurs, ornithosuchids, rauisuchians, and some groups of crocodylomorphs). Finally, the Late Triassic itself was a time of great upheaval in life, with shifts in plant life, marine life, and climate.<ref name="MJB04" /> [[Crurotarsi|Crurotarsans]], today represented only by crocodilians but in the Late Triassic also encompassing such now-extinct groups as aetosaurs, phytosaurs, ornithosuchians, and rauisuchians, were actually more diverse in the Late Triassic than dinosaurs, indicating that the survival of dinosaurs had more to do with luck than superiority.<ref name="SBetal08">{{cite journal|last=Brusatte|first=S.L.|coauthors=Benton, M.J.; Ruta, M.; and Lloyd, G.T.|date=2008|title=Superiority, competition, and opportunism in the evolutionary radiation of dinosaurs|journal=Science|volume=321|issue=5895|pages=1485–1488 |doi=10.1126/science.1161833|pmid=18787166}}</ref>

===Low diversification in the Cretaceous===
Statistical analyses based on raw data suggest that dinosaurs diversified, i.e. the number of species increased, in the Late [[Cretaceous]]. However in July 2008 Graeme T. Lloyd ''et al'' argued that this apparent diversification was an illusion caused by [[sampling bias]], because Late Cretaceous rocks have been very heavily studied. Instead, they wrote, dinosaurs underwent only two significant diversifications in the Late Cretaceous, the initial [[evolutionary radiation| radiations]] of the [[hadrosaur| euhadrosaurs]] and [[ceratopsian]]s. In the Mid Cretaceous, the flowering [[angiosperm]] plants became a major part of terrestrial [[ecosystem]]s, which had previous been dominated by [[gymnosperm]]s such as conifers. Dinosaur [[coprolite]]s (fossilized dung) indicate that, while some ate angiosperms, most herbivorous dinosaurs mainly ate gymnosperms. Meanwhile [[herbivorous]] insects and [[mammal]]s diversified rapidly to take advantage of the new type of plant food, while lizards, snakes, [[crocodilian]]s and [[bird]]s also diversified at the same time. Lloyd ''et al'' suggest that dinosaurs' failure to diversify as ecosystems were changing doomed them to extinction.<ref name="LloydDavisPisaniEtAl2008DinosAndKTR">{{cite journal
|title=Dinosaurs and the Cretaceous Terrestrial Revolution
|author=Lloyd, G.T., Davis, K.E., Pisani, D., ''et al''
|journal=Proceedings of the Royal Society: Biology |date=22 July 2008 |doi=10.1098/rspb.2008.0715
|url=http://journals.royalsociety.org/content/7k63203q852h4006/ |accessdate=2008-07-28
|volume=275
|pages=2483
}} The URL contains links to all the content, and it's all free.</ref>

===Classification===
{{main|Dinosaur classification}}

Dinosaurs (including birds) are [[archosaur]]s, like modern [[crocodilia]]ns. Archosaurs' [[diapsid]] skulls have two holes, called [[temporal fenestrae]], located where the jaw muscles attach, and an additional [[antorbital fenestra]] in front of the eyes. Most reptiles (including birds) are diapsids; mammals, with only one temporal fenestra, are called [[synapsid]]s; and [[turtle]]s, with no temporal fenestra, are [[anapsid]]s. Anatomically, dinosaurs share many other archosaur characteristics, including teeth that grow from sockets rather than as direct extensions of the jawbones. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodylians sprawl out to either side.

Collectively, dinosaurs are usually regarded as a [[superorder]] or an unranked [[clade]]. They are divided into two [[Order (biology)|orders]], [[Saurischia]] and [[Ornithischia]], depending upon [[pelvis|pelvic]] structure. Saurischia includes those taxa sharing a more recent common ancestor with ''birds'' than with Ornithischia, while Ornithischia includes all [[taxon|taxa]] sharing a more recent common ancestor with ''[[Triceratops]]'' than with Saurischia. Saurischians ('lizard-hipped', from the [[Ancient Greek|Greek]] ''sauros'' (''σαυρος'') meaning 'lizard' and ''ischion'' (''ισχιον'') meaning 'hip joint') retained the hip structure of their ancestors, with a [[pubis (bone)|pubis]] bone directed [[anatomical terms of location|cranially]], or forward.<ref name=MJB00/> This basic form was modified by rotating the pubis backward to varying degrees in several groups (''[[Herrerasaurus]]'',<ref name=GSP88>{{cite book|last=Paul |first=G.S. |year=1988 |title=Predatory Dinosaurs of the World |location=New York |publisher=Simon and Schuster |pages=248–250 }}</ref> [[therizinosaur]]oids,<ref name="clarketal2004">Clark, J.M., Maryanska, T., and Barsbold, R. (2004). "Therizinosauroidea", in ''The Dinosauria'', 2nd ed. 151–164.</ref> [[dromaeosauridae|dromaeosaurids]],<ref name=MAPM04>Norell, M.A., and Makovicky, P.J. (2004). "Dromaeosauridae", in ''The Dinosauria'', 2nd ed. 196-210.</ref> and [[bird]]s<ref name=KP04/>). Saurischia includes the [[Theropoda|theropods]] (bipedal and mostly carnivores, except for birds) and [[Sauropodomorpha|sauropodomorphs]] (long-necked quadrupedal [[herbivore]]s).

By contrast, ornithischians ('bird-hipped', from the [[Ancient Greek|Greek]] ''ornitheios'' (''ορνιθειος'') meaning 'of a bird' and ''ischion'' (''ισχιον'') meaning 'hip joint') had a pelvis that superficially resembled a bird's pelvis: the [[pubis (bone)|pubis]] bone was oriented [[anatomical terms of location|caudally]] (rear-pointing). Unlike birds, the ornithischian pubis also usually had an additional forward-pointing process. Ornithischia includes a variety of herbivores. ('''NB:''' the terms "lizard hip" and "bird-hip" are misnomers{{ndash}} birds evolved from dinosaurs with "lizard hips".)

<center><gallery>
Image:Saurischia.png|[[Saurischia]]n pelvis structure (left side)
Image:Tyrannosaurus pelvis left.jpg|''[[Tyrannosaurus]]'' pelvis (showing saurischian structure - left side)
Image:Ornithischia.png|[[Ornithischia]]n pelvis structure (left side).
Image:Edmontosaurus pelvis left.jpg|''[[Edmontosaurus]]'' pelvis (showing ornithischian structure - left side)
</gallery></center>

The following is a simplified classification of dinosaur families. A more detailed version can be found at [[List of dinosaur classifications]].

[[Image:Struthiomimus altus jconway.jpg|thumb|300px|''[[Struthiomimus]]'', an ostrich-like [[theropod]] dinosaur.]]
*Dinosauria
:*[[Saurischia]] (theropods and sauropods)
::*[[Herrerasaur]]ians (early bipedal predators)
::*[[Theropod]]s (all [[Bipedalism| bipedal]]; most were carnivores)
:::*[[Coelophysoidea|Coelophysoids]] (''[[Coelophysis]]'' and close relatives)
:::*[[Ceratosauria]]ns (''[[Ceratosaurus]]'' and [[abelisaur]]ids - the latter were important Late Cretaceous predators in southern continents)
:::*[[Spinosauroidea|Spinosauroids]] (long bodies, short arms, some with crocodile-like skulls and bony "sails" in their backs)
:::*[[Carnosauria]]ns (''[[Allosaurus]]'' and close relatives, like ''[[Carcharodontosaurus]]'')
:::*[[Coelurosauria]]ns (diverse, with a range of body sizes and niches)
::::*[[Tyrannosauroidea|Tyrannosauroids]] (small to gigantic, often with reduced forelimbs)
::::*[[Ornithomimosauria]]ns ("[[ostrich]]-mimics", toothless, carnivores to herbivores)
::::*[[Therizinosaur]]oids (bipedal herbivores with long arms and small heads)
::::*[[Oviraptorosauria]]ns (toothless; their diet and lifestyle are uncertain)
::::*[[Dromaeosauridae|Dromaeosaurids]] (like the "raptors" in ''[[Jurassic Park]]'')
::::*[[Troodontidae|Troodontids]] (similar to dromaeosaurids, but more lightly built, and possibly omnivorous)
::::*[[Aves|Birds]] (the only living dinosaurs)
[[Image:Brachiosaurus-brancai jconway.jpg|thumb|300px|''[[Brachiosaurus]]'' is an example of a [[sauropod]] dinosaur.]]
::*[[Sauropodomorpha|Sauropodomorphs]] (quadrupedal herbivores with small heads and long necks and tails, and elephant-like bodies)
:::*"[[Prosauropoda|Prosauropods]]" (early relatives of sauropods; small to quite large; some possibly omnivorous; bipeds and quadrupeds)
:::*[[Sauropoda|Sauropods]] (very large, usually over 15 meters long [49 ft])
::::*[[Diplodocoidea|Diplodocoids]] (skulls and tails elongated; teeth typically narrow and pencil-like)
::::*[[Macronaria]]ns (boxy skulls; spoon-shaped or pencil-shaped teeth)
:::::*[[Brachiosauridae|Brachiosaurids]] (very long necks; forelimbs longer than hindlimbs)
:::::*[[Titanosauria]]ns (diverse; stocky, with wide hips; most common in the Late Cretaceous of southern continents)
[[Image:Ornithopods jconway.jpg|300px|thumb|Various [[ornithopod]] dinosaurs and one [[heterodontosaurid]]. Far left: ''[[Camptosaurus]]'', left: ''[[Iguanodon]]'', center background: ''[[Shantungosaurus]]'', center foreground: ''[[Dryosaurus]]'', right: ''[[Corythosaurus]]'', far right (small): ''[[Heterodontosaurus]]'', far right (large) ''[[Tenontosaurus]]''.]]
:*[[Ornithischia]]ns (diverse bipedal and quadrupedal herbivores)
::*[[Heterodontosauridae|Heterodontosaurids]] (meter- or yard-scale herbivores or omnivores with prominent canine teeth)
::*[[Thyreophora]]ns (armored dinosaurs, mostly quadrupeds)
:::*[[Ankylosauria]]ns ([[scutes]] as primary armor; some had club-like tails)
:::*[[Stegosauria]]ns (spikes and plates as primary armor)
::*[[Ornithopoda|Ornithopods]] (diverse, from meter- or yard-scale bipeds to 12 meter (39 ft) animals that could moves as both bipeds and quadrupeds, evolved a method of chewing using skull flexibility and large numbers of teeth)
:::*[[Hadrosaur]]ids ("duckbilled dinosaurs")
::*[[Pachycephalosauria]]ns ("bone-heads", bipeds with domed or knobby growth on skulls)
::*[[Ceratopsia]]ns (dinosaurs with horns and frills, although most early forms had only the beginnings of these features)

===Evolution and paleobiogeography===
{{main|Evolution of dinosaurs}}

Dinosaur evolution after the Triassic follows changes in vegetation and the location of continents. In the Late Triassic and Early Jurassic, the continents were connected as the single landmass [[Pangaea]], there was a worldwide dinosaur fauna mostly composed of [[coelophysoidea|coelophysoid]] [[carnivore]]s and [[prosauropod]] [[herbivore]]s.<ref name=HCL04>{{cite book |last=Holtz |first=Thomas R., Jr. |coauthors=Chapman, Ralph E.; and Lamanna, Matthew C. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.)|title=The Dinosauria |edition=2nd |year=2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=627–642 |chapter=Mesozoic biogeography of Dinosauria}}</ref> [[Gymnosperm]] plants (particularly [[conifer]]s), a potential food source, radiated in the Late Triassic. Prosauropods did not have sophisticated mechanisms for processing food in the mouth, so must have employed other means of breaking down food farther along the digestive tract.<ref name=FS04>{{cite book |last=Fastovsky |first=David E. |coauthors=and Smith, Joshua B. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.)|title=The Dinosauria |edition=2nd |year=2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=614–626 |chapter=Dinosaur paleoecology}}</ref> The general homogeneity of dinosaurian faunas continued into the Middle and Late Jurassic, where most localities had predators consisting of [[ceratosauria]]ns, [[spinosauroidea|spinosauroids]], and [[carnosauria]]ns, and herbivores consisting of [[stegosauria]]n ornithischians and large sauropods. Examples of this include the [[Morrison Formation]] of North America and [[Tendaguru|Tendaguru Beds]] of Tanzania. Dinosaurs in China show some differences, with specialized [[sinraptoridae|sinraptorid]] theropods and unusual, long-necked sauropods like ''[[Mamenchisaurus]]''.<ref name=HCL04/> [[Ankylosauria]]ns and [[ornithopoda|ornithopods]] were also becoming more common, but prosauropods had become extinct. Conifers and [[pteridophyte]]s were the most common plants. Sauropods, like the earlier prosauropods, were not oral processors, but ornithischians were evolving various means of dealing with food in the mouth, including potential [[cheek]]-like organs to keep food in the mouth, and jaw motions to grind food.<ref name=FS04/> Another notable evolutionary event of the Jurassic was the appearance of true birds, descended from [[maniraptora]]n [[coelurosauria]]ns.<ref name=KP04/>
[[Image:CeratopsiaI BW.jpg|right|thumb|200px|An Illustration of 18 species of basal ceratopsia to scale.]]
By the Early Cretaceous and the ongoing breakup of Pangaea, dinosaurs were becoming strongly differentiated by landmass. The earliest part of this time saw the spread of ankylosaurians, [[iguanodontia]]ns, and [[brachiosauridae|brachiosaurids]] through Europe, North America, and northern Africa. These were later supplemented or replaced in Africa by large [[spinosaurid]] and [[carcharodontosauridae|carcharodontosaurid]] theropods, and [[rebbachisauridae|rebbachisaurid]] and [[titanosauria]]n sauropods, also found in South America. In Asia, [[maniraptora]]n [[coelurosauria]]ns like [[dromaeosauridae|dromaeosaurids]], [[troodontidae|troodontid]]s, and [[oviraptorosauria]]ns became the common theropods, and [[ankylosauridae|ankylosaurids]] and early [[ceratopsia]]ns like ''Psittacosaurus'' became important herbivores. Meanwhile, Australia was home to a fauna of basal ankylosaurians, [[hypsilophodont]]s, and iguanodontians.<ref name=HCL04/> The stegosaurians appear to have gone extinct at some point in the late Early Cretaceous or early Late Cretaceous. A major change in the Early Cretaceous, which would be amplified in the Late Cretaceous, was the evolution of [[angiosperm|flowering plants]]. At the same time, several groups of dinosaurian herbivores evolved more sophisticated ways to orally process food. Ceratopsians developed a method of slicing with teeth stacked on each other in batteries, and iguanodontians refined a method of grinding with tooth batteries, taken to its extreme in [[hadrosaurid]]s.<ref name=FS04/> Some sauropods also evolved tooth batteries, best exemplified by the rebbachisaurid ''[[Nigersaurus]]''.<ref name=serenoetal07>{{cite journal |last=Sereno |first=P.C. |coauthors=Wilson, J.A.; Witmer, L.M.; Whitlock, J.A.; Maga, A.; Ide, O.; and Rowe, T.A. |year=2007 |title=Structural extremes in a Cretaceous dinosaur |journal=PLoS ONE |volume=2 |issue=11 |pages=e1230 |url=http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0001230 |doi=10.1371/journal.pone.0001230}}</ref>

There were three general dinosaur faunas in the Late Cretaceous. In the northern continents of North America and Asia, the major theropods were [[tyrannosauridae|tyrannosaurid]]s and various types of smaller maniraptoran theropods, with a predominantly ornithischian herbivore assemblage of hadrosaurids, ceratopsians, ankylosaurids, and [[pachycephalosauria]]ns. In the southern continents that had made up the now-splitting [[Gondwana]], [[abelisauridae|abelisaurids]] were the common theropods, and titanosaurian sauropods the common herbivores. Finally, in Europe, dromaeosaurids, [[rhabdodontidae|rhabdodontid]] iguanodontians, [[nodosauridae|nodosaurid]] ankylosaurians, and titanosaurian sauropods were prevalent.<ref name=HCL04/> Flowering plants were greatly radiating,<ref name=FS04/> with the first grasses appearing by the end of the Cretaceous.<ref name=PSAS05>{{cite journal |last=Prasad |first=V. |coauthors=Strömberg, C.A.E.; Alimohammadian, H; and Sahni, A. |year=2005 |title=Dinosaur coprolites and the early evolution of grasses and grazers |journal=Science |volume=310 |issue=5751 |pages=1170–1180 |doi=10.1126/science.1118806 |pmid=16293759}}</ref> Grinding hadrosaurids and shearing ceratopsians became extremely diverse across North America and Asia. Theropods were also radiating as herbivores or omnivores, with [[therizinosaur]]ians and [[ornithomimosauria]]ns becoming common.<ref name=FS04/>

The [[Cretaceous–Tertiary extinction event]], which occurred approximately 65 million years ago at the end of the Cretaceous period, caused the extinction of all dinosaurs except for the birds. Some other [[diapsid]] groups, such as crocodylians, [[lizard]]s, [[snake]]s, [[sphenodontia]]ns, and [[choristodera]]ns, also survived the event.<ref name=AF04>{{cite book |last=Archibald |first=J. David |coauthors=and Fastovsky, David E. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.)|title=The Dinosauria |edition=2nd |year=2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=672–684 |chapter=Dinosaur Extinction}}</ref>

==Paleobiology==
Knowledge about dinosaurs is derived from a variety of fossil and non-fossil records, including [[fossil]]ized [[bone]]s, [[feces]], [[trackway]]s, [[gastrolith]]s, [[feather]]s, impressions of skin, [[Viscus|internal organs]] and [[soft tissue]]s.<ref name="softtissue">{{cite journal|author=Dal Sasso, C. and Signore, M. |date=1998)|title=Exceptional soft-tissue preservation in a theropod dinosaur from Italy|journal=Nature|volume=292|issue=6674|pages=383–387|doi=10.1038/32884}}</ref><ref name="Schweitzer2005"/> Many fields of study contribute to our understanding of dinosaurs, including [[physics]] (especially [[biomechanics]]), [[chemistry]], [[biology]], and the [[earth sciences]] (of which [[paleontology]] is a sub-discipline). Two topics of particular interest and study have been dinosaur size and behavior.

===Size===
{{main|Dinosaur size}}
[[Image:Largestdinosaursbysuborder scale.png|thumb|400px|right|Scale diagram comparing the largest known dinosaurs in four [[Order (biology)|suborders]] and a human.]]
While the evidence is incomplete, it is clear that, as a group, dinosaurs were large. Even by dinosaur standards, the [[Sauropoda|sauropods]] were gigantic. For much of the dinosaur era, the smallest sauropods were larger than anything else in their habitat, and the largest were an [[order of magnitude]] more massive than anything else that has since walked the Earth. Giant prehistoric [[mammal]]s such as the ''[[Indricotherium]]'' and the Columbian [[mammoth]] were dwarfed by the giant sauropods, and only a handful of modern aquatic animals approach or surpass them in size{{ndash}} most notably the [[blue whale]], which reaches up to {{kg to lb|173000|precision=-3}} and over {{m to ft|30|precision=-1}} in length.<ref name=Cosewic>{{cite web|url=http://www.wildwhales.org/cetaceans/blue/sr_blue_whale_e.pdf.pdf|publisher=Committee on the Status of Endangered Wildlife in Canada|date=2002|title=Assessment and Update Status Report on the Blue Whale ''Balaenoptera musculus''|accessdate=2007-12-05}}</ref> There are several proposed advantages for the large size of sauropods, including protection from predation, reduction of energy use, and longevity, but it may be that the most important advantage was dietary. Large animals are more efficient at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in [[rock formation]]s interpreted as dry or seasonally dry, and the ability to eat large quantities of low nutrient browse would have been advantageous in such environments.<ref name=KC06>{{cite book |last=Carpenter |first=Kenneth |authorlink=Kenneth Carpenter |year=2006 |chapter=Biggest of the big: a critical re-evaluation of the mega-sauropod ''Amphicoelias fragillimus'' |editor=Foster, John R.; and Lucas, Spencer G. (eds.) |title=Paleontology and Geology of the Upper Jurassic Morrison Formation |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque |series=New Mexico Museum of Natural History and Science Bulletin '''36''' |pages=131–138 |url=https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/Amphicoelias.pdf |format=pdf}}</ref>

Most dinosaurs, however, were much smaller than the giant sauropods. Current evidence suggests that dinosaur average size varied through the Triassic, early Jurassic, late Jurassic and Cretaceous periods.<ref name="Sereno1999"/> Theropod dinosaurs, when sorted by estimated weight into categories based on [[order of magnitude]], most often fall into the 100 to 1,000 kilogram (220 to 2,200 lb) category, whereas [[Holocene|recent]] predatory [[carnivora]]ns peak in the 10 to 100 kilogram (22 to 220 lb) category.<ref name=JF93>{{cite book |last=Farlow |first=James A. |authorlink=James Farlow |year=1993 |title=Functional Morphology and Evolution |editors=Dodson, Peter; and Gingerich, Philip |series=American Journal of Science, Special Volume '''293-A''' |chapter=On the rareness of big, fierce animals: speculations about the body sizes, population densities, and geographic ranges of predatory mammals and large, carnivorous dinosaurs |pages=167–199}}</ref> The [[Mode (statistics)|mode]] of dinosaur body masses is between one and ten metric tonnes.<ref>Peczkis, J. (1994). "Implications of body-mass estimates for dinosaurs". ''Journal of Vertebrate Paleontology'' '''14'''(4): 520-33</ref> This contrasts sharply with the size of [[Cenozoic]] mammals, estimated by the [[National Museum of Natural History]] as about 2 to 5 kilograms (5 to 10 lb).<ref name=NMNH>{{cite web |url=http://paleobiology.si.edu/dinosaurs/info/everything/evo_1.html |title=Anatomy and evolution |accessdate=2007-11-21 |publisher=National Museum of Natural History}}</ref>

====Largest and smallest====
Only a tiny percentage of animals ever fossilize, and most of these remain buried in the earth. Few of the specimens that are recovered are complete skeletons, and impressions of skin and other soft tissues are rare. Rebuilding a complete skeleton by comparing the size and morphology of bones to those of similar, better-known species is an inexact art, and reconstructing the muscles and other organs of the living animal is, at best, a process of educated guesswork. As a result, scientists will probably never be certain of the [[largest organism|largest and smallest dinosaurs]].

[[Image:Brachiosaurus scale.png|thumb|160px|right|Comparative size of ''[[Brachiosaurus]]''.]]
The tallest and heaviest dinosaur known from good skeletons is ''[[Brachiosaurus|Brachiosaurus brancai]]'' (also known as ''[[Giraffatitan]]''). Its remains were discovered in [[Tanzania]] between 1907–12. Bones from multiple similarly-sized individuals were incorporated into the skeleton now mounted and on display at the [[Humboldt Museum]] of [[Berlin]];<ref name=EC68>Colbert, E.H. (1968). ''Men and Dinosaurs: The Search in Field and Laboratory.'' E. P. Dutton & Company:New York, vii + 283 p. ISBN 0140212884.</ref> this mount is {{m to ft|12}} tall and {{m to ft|22.5}} long, and would have belonged to an animal that weighed between 30,000 and 60,000 kilograms (70,000 and 130,000 lb). The longest complete dinosaur is the 27 m (89 ft) long ''[[Diplodocus]]'', which was discovered in [[Wyoming]] in the [[United States]] and displayed in [[Pittsburgh, Pennsylvania|Pittsburgh's]] [[Carnegie Natural History Museum]] in 1907.
[[Image:Human-eoraptor size comparison(v2).png|thumb|140px|left|Comparative size of ''[[Eoraptor]]''.]]
There were larger dinosaurs, but knowledge of them is based entirely on a small number of fragmentary fossils. Most of the largest [[herbivore|herbivorous]] specimens on record were all discovered in the 1970s or later, and include the massive ''[[Argentinosaurus]]'', which may have weighed 80,000 to 100,000 kilograms (90 to 110 short tons); some of the longest, the {{m to ft|33.5|precision=-1}} long ''[[Diplodocus|Diplodocus hallorum]]''<ref name=KC06/> (formerly ''Seismosaurus'') and the {{m to ft|33|precision=-1}} long ''[[Supersaurus]]'';<ref name=LHW07>{{cite journal |last=Lovelace |first=David M. |coauthors=Hartman, Scott A.; and Wahl, William R. |year=2007 |title=Morphology of a specimen of ''Supersaurus'' (Dinosauria, Sauropoda) from the Morrison Formation of Wyoming, and a re-evaluation of diplodocid phylogeny |journal=Arquivos do Museu Nacional |volume=65 |issue=4 |pages=527–544 }}</ref> and the tallest, the {{m to ft|18}} ''[[Sauroposeidon]]'', which could have reached a sixth-floor window. The longest of them all may have been ''[[Amphicoelias|Amphicoelias fragillimus]]'', known only from a now lost partial vertebral [[neural arch]] described in 1878. Extrapolating from the illustration of this bone, the animal may have been {{m to ft|58}} long and weighed over {{kg to lb|120000|precision=-4}},<ref name=KC06/> heavier than all known dinosaurs except possibly the poorly known ''[[Bruhathkayosaurus]]'', which could have weighed 175,000 to 220,000 kilograms (400,000 to 500,000 lb). The largest known [[carnivore|carnivorous]] dinosaur was ''[[Spinosaurus]]'', reaching a length of 16 to 18 meters (50 to 60 ft), and weighing in at {{kg to lb|8150|precision=-2}}.<ref name=SMBM06>dal Sasso, C., Maganuco, S., Buffetaut, E., and Mendez, M.A. (2006). New information on the skull of the enigmatic theropod ''Spinosaurus'', with remarks on its sizes and affinities. ''Journal of Vertebrate Paleontology'' '''25'''(4):888–896.</ref> Other large meat-eaters included ''[[Giganotosaurus]]'', ''[[Mapusaurus]]'', ''[[Tyrannosaurus|Tyrannosaurus rex]]'' and ''[[Carcharodontosaurus]]''.

Not including modern birds, the smallest dinosaurs known were about the size of a [[crow]] or a [[chicken]]. The theropods ''[[Microraptor]]'' and ''[[Parvicursor]]'' were both under 0.6 meters (2 ft) in length.

===Behavior===
[[Image:Maiasaurusnest.jpg|thumb|210px|A nesting ground of ''[[Maiasaura]]'' was discovered in 1978.]]

Interpretations of dinosaur behavior are generally based on the pose of body fossils and their [[Habitat (ecology)|habitat]], [[computer simulation]]s of their [[biomechanics]], and comparisons with modern animals in similar [[ecological niche]]s. As such, the current understanding of dinosaur behavior relies on speculation, and will likely remain controversial for the foreseeable future. However, there is general agreement that some behaviors which are common in crocodiles and birds, dinosaurs' closest living relatives, were also common among dinosaurs.

The first potential evidence of [[herd]]ing behavior was the 1878 discovery of 31 ''[[Iguanodon]]'' dinosaurs which were then thought to have perished together in [[Bernissart]], [[Belgium]], after they fell into a deep, flooded [[sinkhole]] and drowned.<ref>{{cite journal|author=Yans J, Dejax J, Pons D, Dupuis C & Taquet P|date=2005|title=Implications paléontologiques et géodynamiques de la datation palynologique des sédiments à faciès wealdien de Bernissart (bassin de Mons, Belgique)|journal=Comptes Rendus Palevol|volume=4|issue=1-2|pages=135–150|language=French|doi=10.1016/j.crpv.2004.12.003}}</ref> Other mass death sites have been subsequently discovered. Those, along with multiple trackways, suggest that gregarious behavior was common in many dinosaur species. Trackways of hundreds or even thousands of herbivores indicate that [[Hadrosaurid|duck-bills]] (hadrosaurids) may have moved in great herds, like the [[American Bison]] or the African [[Springbok Antelope|Springbok]]. Sauropod tracks document that these animals traveled in groups composed of several different species, at least in [[Oxfordshire]], England,<ref>{{cite journal |last=Day |first=J.J. |coauthors=and Upchurch, P. |year=2002 |title=Sauropod trackways, evolution, and behavior |journal=Science |volume=296 |pages=1659|doi=10.1126/science.1070167 |pmid=12040187 }}</ref> although there is not evidence for specific herd structures.<ref name=JLW05>{{cite book |last=Wright |first=Joanna L. |year=2005 |chapter=Steps in understanding sauropod biology |title=The Sauropods: Evolution and Paleobiology |editor=Curry Rogers, Kristina A.; and Wilson, Jeffrey A. |publisher=University of California Press |location=Berkeley |pages=252–284 |isbn=0-520-24623-3}}</ref> Dinosaurs may have congregated in herds for defense, for [[Bird migration|migratory]] purposes, or to provide protection for their young. The interpretation of dinosaurs as gregarious has also extended to depicting carnivorous theropods as [[pack hunter]]s working together to bring down large prey.<ref name=LG93>{{cite book |last=Lessem |first=Don |coauthors=and Glut, Donald F. |year=1993 |title=The Dinosaur Society's Dinosaur Encyclopedia |chapter=''Allosaurus'' |pages=19–20|publisher=Random House|isbn=0-679-41770-2}}</ref><ref name="maxwell&ostrom1995">{{cite journal|last=Maxwell|first=W. D. |coauthors=Ostrom, J.H. |year=1995 |title=Taphonomy and paleobiological implications of ''Tenontosaurus''-''Deinonychus'' associations|journal=Journal of Vertebrate Paleontology |volume=15 |issue=4 |pages=707–712}}([http://www.vertpaleo.org/publications/jvp/15-707-712.cfm abstract])</ref> However, this lifestyle is uncommon among the modern relatives of dinosaurs ([[crocodile]]s and other reptiles, and [[bird]]s - [[Harris's Hawk]] is a well-documented exception), and the [[taphonomy|taphonomic]] evidence suggesting pack hunting in such theropods as ''[[Deinonychus]]'' and ''[[Allosaurus]]'' can also be interpreted as the results of fatal disputes between feeding animals, as is seen in many modern [[diapsid]] predators.<ref name=RB07>{{cite journal|last=Roach|first=Brian T.|coauthors=and Brinkman, Daniel L. |year=2007 |title=A reevaluation of cooperative pack hunting and gregariousness in ''Deinonychus antirrhopus'' and other nonavian theropod dinosaurs|journal=Bulletin of the Peabody Museum of Natural History |volume=48 |issue=1 |pages=103–138 |doi=10.3374/0079-032X(2007)48[103:AROCPH]2.0.CO;2}}</ref>
[[Image:Dino eggP9240092.JPG|thumb|right|Fossilized egg of the [[oviraptoridae|oviraptorid]] ''[[Citipati]]'', [[American Museum of Natural History]].]]
[[Jack Horner (paleontologist)|Jack Horner's]] 1978 discovery of a ''[[Maiasaura]]'' ("good mother dinosaur") [[nest]]ing ground in [[Montana]] demonstrated that parental care continued long after birth among the [[ornithopod]]s.<ref name=HM79>{{cite journal |last=Horner |first=J.R. |coauthors=and Makela, R. |year=1979 |title=Nest of juveniles provides evidence of family-structure among dinosaurs |journal=Nature |volume=282 |issue=5736 |pages=296–298 |doi=10.1038/282296a0}}</ref> There is also evidence that other Cretaceous-era dinosaurs, like [[Patagonia]]n [[titanosaur]]ian sauropods (1997 discovery), also nested in large groups.<ref name=LMCetal05>{{cite book |last=Chiappe |first=Luis M. |coauthors=Jackson, Frankie; Coria, Rodolfo A.; and Dingus, Lowell |year=2005 |chapter=Nesting titanosaurs from Auca Mahuevo and adjacent sites |title=The Sauropods: Evolution and Paleobiology |editor=Curry Rogers, Kristina A.; and Wilson, Jeffrey A. |publisher=University of California Press |location=Berkeley |pages=285–302 |isbn=0-520-24623-3}}</ref> The [[Mongolia]]n [[oviraptoridae|oviraptorid]] ''[[Citipati]]'' was discovered in a [[chicken]]-like [[Avian incubation|brooding]] position in 1993, which may mean it was covered with an insulating layer of feathers that kept the [[egg (biology)|eggs]] warm.<ref>[http://search.eb.com/dinosaurs/dinosaurs/BRa.html Oviraptor nesting] ''[[Oviraptor]]'' nests or ''[[Protoceratops]]''?</ref> Parental care is also implied by other finds. For example, the fossilized remains of a grouping of ''[[Psittacosaurus]]'' has been found, consisting of one adult and 34 juveniles; in this case, the large number of juveniles may be due to communal nesting.<ref name=mengetal2004>{{cite journal |author=Meng Qingjin; Liu Jinyuan; Varricchio, David J.; Huang, Timothy; and Gao Chunling |year=2004 |title=Parental care in an ornithischian dinosaur |journal=Nature |volume=431 |pages=145–146 |doi=10.1038/431145a}}</ref> Additionally, a dinosaur embryo (pertaining to the [[prosauropoda|prosauropod]] ''[[Massospondylus]]'') was found without teeth, indicating that some parental care was required to feed the young dinosaur.<ref name="Reiszetal05">{{cite journal|author=Reisz RR, Scott, D Sues, H-D, Evans, DC & Raath, MA|title=Embryos of an Early Jurassic prosauropod dinosaur and their evolutionary significance|journal=Science|volume=309|issue= |pages=761–764|publisher= |location= |date=2005|url= |doi=10.1126/science.1114942|id= |accessdate= | pmid =16051793}}</ref> Trackways have also confirmed parental behavior among ornithopods from the [[Isle of Skye]] in northwestern [[Scotland]].<ref>[http://news.bbc.co.uk/1/hi/scotland/3255494.stm Dinosaur family tracks] Footprints show maternal instinct after leaving the nest.</ref> Nests and eggs have been found for most major groups of dinosaurs, and it appears likely that dinosaurs communicated with their young, in a manner similar to modern birds and crocodiles.

[[Image:Centrosaurus dinosaur.png|thumb|left|225px|Artist's rendering of two ''[[Centrosaurus]]'', herbivorous [[ceratopsidae|ceratopsid]] dinosaurs from the late Cretaceous fauna of North America.]]
The crests and frills of some dinosaurs, like the [[marginocephalia]]ns, [[theropod]]s and [[lambeosaurine]]s, may have been too fragile to be used for active defense, so they were likely used for sexual or aggressive displays, though little is known about dinosaur mating and [[territory (animal)|territorialism]]. Head wounds from bites suggest that theropods, at least, engaged in active aggressive confrontations.<ref name=PC98>{{cite journal |last=Tanke |first=Darren H. |authorlink=Darren Tanke |coauthors=and Currie, Philip J. |year=1998 |title=Head-biting behavior in theropod dinosaurs: paleopathological evidence |journal=Gaia |issue=15 |pages=167–184 |url=http://www.mnhn.ul.pt/geologia/gaia/12.pdf |issn=0871-5424 |format=pdf}}</ref> The nature of dinosaur [[Animal communication|communication]] also remains enigmatic, and is an active area of research. For example, recent studies suggest that the hollow crests of the lambeosaurines may have functioned as [[resonance chamber]]s used for a wide range of [[Animal communication|vocalizations]].<ref name=JAH75>{{cite journal |last=Hopson |first=James A. |authorlink=James Hopson |year=1975 |title=The evolution of cranial display structures in hadrosaurian dinosaurs |journal=Paleobiology |volume=1 |issue=1 |pages=21–43 |url= |accessdate=}}</ref><ref name=DW98>{{cite journal |last=Diegert |first=Carl F. |coauthors=and Williamson, Thomas E. |year=1998 |title=A digital acoustic model of the lambeosaurine hadrosaur ''Parasaurolophus tubicen'' |journal=Journal of Vertebrate Paleontology |volume=18 |issue=3, Suppl. |pages=38A }}</ref>

From a behavioral standpoint, one of the most valuable dinosaur fossils was discovered in the [[Gobi Desert]] in 1971. It included a ''[[Velociraptor]]'' attacking a ''[[Protoceratops]]'',<ref>{{cite web|url=http://www.amnh.org/exhibitions/fightingdinos/ex-fd.html|title=The Fighting Dinosaurs|publisher=American Museum of Natural History|accessdate=2007-12-05}}</ref> providing evidence that dinosaurs did indeed attack each other.<ref name=carpenter1998>{{cite journal |last=Carpenter |first=K. |authorlink=Kenneth Carpenter |year=1998 |title=Evidence of predatory behavior by theropod dinosaurs |journal=Gaia |volume=15 |pages=135–144 |url=http://vertpaleo.org/publications/jvp/15-576-591.cfm|accessdate=2007-12-05}}</ref> Additional evidence for attacking live prey is the partially-healed tail of an ''[[Edmontosaurus]]'', a hadrosaurid dinosaur; the tail is damaged in such a way that shows the animal was bitten by a tyrannosaur but survived.<ref name=carpenter1998/> [[Cannibalism (zoology)|Cannibalism]] amongst some species of dinosaurs was confirmed by tooth marks found in Madagascar in 2003, involving the theropod ''[[Majungasaurus]]''.<ref name=rogersetal2003>{{cite_journal |last=Rogers |first=Raymond R. |coauthors=Krause, David W.; & [[Kristina Curry Rogers|Curry Rogers, Kristina]]. |year=2007 |title=Cannibalism in the Madagascan dinosaur ''Majungatholus atopus'' |journal=Nature |volume=422 |issue=6931 |pages=515–518 |doi=10.1038/nature01532}}</ref>

Based on current fossil evidence from dinosaurs such as ''[[Oryctodromeus]]'', some herbivorous species seem to have led a partially [[fossorial]] (burrowing) lifestyle,<ref name=VMK07>{{cite journal |author=Varricchio DJ, Martin, AJ and Katsura, Y|year=2007 |title=First trace and body fossil evidence of a burrowing, denning dinosaur |journal=Proceedings of the Royal Society B: Biological Sciences |volume=274|issue=1616|pages=1361–1368 |doi=10.1098/rspb.2006.0443}}</ref> and some bird-like species may have been [[arboreal]] (tree-climbing), most notably primitive [[Dromaeosauridae|dromaeosaurids]] such as ''[[Microraptor]]''<ref name="chatterjee2007">{{cite journal |last=Chatterjee |first=S. |coauthors=and Templin, R.J. |year=2007 |title=Biplane wing planform and flight performance of the feathered dinosaur ''Microraptor gui'' |journal=Proceedings of the National Academy of Sciences |volume=104 |issue=5 |pages=1576–1580 |url=http://www.pnas.org/cgi/reprint/0609975104v1.pdf |format=pdf |doi=10.1073/pnas.0609975104 }}</ref> and the enigmatic [[scansoriopterygidae|scansoriopterygids]].<ref name="zhang2002">{{cite journal |author=Zhang, F.; Zhou, Z.; Xu, X.; and Wang, X. |year=2002 |title=A juvenile coelurosaurian theropod from China indicates arboreal habits |journal=Naturwissenschaften |volume=89 |issue=9 |pages=394–398 |doi=10.1007 /s00114-002-0353-8}}</ref> However, most dinosaurs seem to have relied on land-based locomotion. A good understanding of how dinosaurs moved on the ground is key to models of dinosaur behavior; the science of [[biomechanics]], in particular, has provided significant insight in this area. For example, studies of the forces exerted by muscles and gravity on dinosaurs' skeletal structure have investigated how fast dinosaurs could run,<ref>{{cite journal|author=Alexander RM|title=Dinosaur biomechanics|journal=Proceedings of the Royal Society of Biological Sciences|volume=273|issue=1596|date=2006|pages=1849–1855|doi=10.1098/rspb.2006.3532}}</ref> whether [[diplodocid]]s could create [[sonic boom]]s via [[whip]]-like tail snapping,<ref>{{cite journal|author=Goriely A & McMillen T|title=Shape of a cracking whip|date=2002|journal=Physical Review Letters|volume=88|issue=24|pages=244301|doi=10.1103/PhysRevLett.88.244301}}</ref> and whether sauropods could float.<ref>{{cite journal|author=Henderson, D.M.|date=2003|title=Effects of stomach stones on the buoyancy and equilibrium of a floating crocodilian: A computational analysis|journal=Canadian Journal of Zoology|volume=81|issue=8|pages=1346–1357|doi=10.1139/z03-122}}</ref>

===Physiology===
{{main|Physiology of dinosaurs}}
[[Image:Palais de la Decouverte Tyrannosaurus rex p1050042.jpg|210px|thumb|right|''[[Tyrannosaurus|Tyrannosaurus rex]]'' skull and upper vertebral column, Palais de la Découverte, Paris.]]
[[Image:Eubrontes01.JPG|210px|thumb|right|''Eubrontes'', a dinosaur footprint in the Lower [[Jurassic]] Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm, southwestern Utah.]]
A vigorous debate on the subject of temperature regulation in dinosaurs has been ongoing since the 1960s. Originally, scientists broadly disagreed as to whether dinosaurs were capable of regulating their body temperatures at all. More recently, dinosaur [[Warm-blooded|endotherm]] has become the consensus view, and debate has focused on the mechanisms of temperature regulation.

After dinosaurs were discovered, paleontologists first posited that they were [[ectotherm]]ic creatures: "terrible [[lizard]]s" as their name suggests. This supposed cold-bloodedness implied that dinosaurs were relatively slow, sluggish organisms, comparable to modern reptiles, which need external sources of heat in order to regulate their body temperature. Dinosaur ectothermy remained a prevalent view until [[Robert T. Bakker|Robert T. "Bob" Bakker]], an early proponent of dinosaur endothermy, published an influential paper on the topic in 1968.

Modern evidence indicates that dinosaurs thrived in cooler temperate climates, and that at least some dinosaur species must have regulated their body temperature by internal biological means (perhaps aided by the animals' bulk). Evidence of [[Warm-blooded|endotherm]] in dinosaurs includes the discovery of [[polar dinosaurs in Australia]] and [[Antarctica]] (where they would have experienced a cold, dark six-month winter), the discovery of dinosaurs whose feathers may have provided regulatory insulation, and analysis of blood-vessel structures that are typical of endotherms within dinosaur bone. Skeletal structures suggest that theropods and other dinosaurs had active lifestyles better suited to an endothermic cardiovascular system, while sauropods exhibit fewer endothermic characteristics. It is certainly possible that some dinosaurs were endothermic while others were not. Scientific debate over the specifics continues.<ref>Parsons, K.M. (2001). ''Drawing Out Leviathan''. Indiana University Press. 22–48. ISBN 0-253-33937-5.</ref>

Complicating the debate is the fact that warm-bloodedness can emerge based on more than one mechanism. Most discussions of dinosaur endothermy tend to compare them to average birds or mammals, which expend energy to elevate body temperature above that of the environment. Small birds and mammals also possess [[thermal insulation|insulation]], such as [[fat]], [[fur]], or [[feather]]s, which slows down heat loss. However, large mammals, such as elephants, face a different problem because of their relatively small ratio of surface area to volume ([[J. B. S. Haldane|Haldane's]] principle). This ratio compares the volume of an animal with the area of its skin: as an animal gets bigger, its surface area increases more slowly than its volume. At a certain point, the amount of heat radiated away through the skin drops below the amount of heat produced inside the body, forcing animals to use additional methods to avoid overheating. In the case of elephants, they have little hair as adults, and have large ears which increase their surface area, and have behavioral adaptations as well (such as using the trunk to spray water on themselves and mud wallowing). These behaviors increase cooling through evaporation.

Large dinosaurs would presumably have had to deal with similar issues; their body size suggest they lost heat relatively slowly to the surrounding air, and so could have been what are called [[gigantothermy|inertial homeotherms]], animals that are warmer than their environments through sheer size rather than through special adaptations like those of birds or mammals. However, so far this theory fails to account for the numerous dog- and goat-sized dinosaur species, or the young of larger species.

Modern [[computerized tomography]] (CT) scans of a [[Thescelosaurus|dinosaur]]'s chest cavity (conducted in 2000) found the apparent remnants of a four-chambered heart, much like those found in today's mammals and birds.<ref>{{cite journal|author=Fisher, P. E., Russell, D. A., Stoskopf, M. K., Barrick, R. E., Hammer, M. & Kuzmitz, A. A.|date=2000|title=Cardiovascular evidence for an intermediate or higher metabolic rate in an ornithischian dinosaur|journal=Science|volume=288|issue=5465|pages=503–505|doi=10.1126/science.288.5465.503|pmid=10775107}}</ref> The idea is controversial within the scientific community, coming under fire for bad anatomical science<ref>{{cite journal|author=Hillenius, W. J. & Ruben, J. A.|date=2004|title=The evolution of endothermy in terrestrial vertebrates: Who? when? why?|journal=Physiological and Biochemical Zoology|volume=77|issue=6|pages=1019–1042|doi=10.1086/425185}}</ref> or simply wishful thinking.<ref>{{cite journal|title=Dinosaur with a Heart of Stone|author=Rowe T, McBride EF, & Sereno PC |date=2001 |journal=Science |volume=291 |issue=5505 |pages=783 |doi=10.1126/science.291.5505.783a|pmid=11157158}}</ref> The question of how this find reflects on metabolic rate and dinosaur internal anatomy may be moot, though, regardless of the object's identity: both modern [[crocodilia]]ns and [[bird]]s, the closest living relatives of dinosaurs, have four-chambered hearts (albeit modified in crocodilians), so dinosaurs probably had them as well.<ref name=CH04>Chinsamy, Anusuya; and Hillenius, Willem J. (2004). "Physiology of nonavian dinosaurs". ''The Dinosauria'', 2nd. 643–659.</ref>

===Soft tissue and DNA===
[[Image:9119 - Milano, Museo storia naturale - Scipionyx samniticus - Foto Giovanni Dall'Orto 22-Apr-2007.jpg|thumb|''Scipionyx samniticus'' fossil showing tissue impressions, at the [[Museo Civico di Storia Naturale de Milan|Museo Civico di Storia Naturale]], in Milan, Italy.]]
One of the best examples of soft tissue impressions in a fossil dinosaur was discovered in [[Petraroia]], [[Italy]]. The discovery was reported in 1998, and described the specimen of a small, very young [[coelurosaur]], ''[[Scipionyx]] samniticus''. The fossil includes portions of the intestines, colon, liver, muscles, and windpipe of this immature dinosaur.<ref name="softtissue" />

In the March 2005 issue of ''[[Science (journal)|Science]]'', the paleontologist [[Mary Higby Schweitzer]] and her team announced the discovery of flexible material resembling actual soft tissue inside a 68-million-year-old ''[[Tyrannosaurus|Tyrannosaurus rex]]'' leg [[bone]] from the [[Hell Creek Formation]] in [[Montana]]. After recovery, the tissue was rehydrated by the science team.<ref name="Schweitzer2005"/>

When the fossilized bone was treated over several weeks to remove mineral content from the fossilized bone marrow cavity (a process called demineralization), Schweitzer found evidence of intact structures such as [[blood vessel]]s, bone matrix, and connective tissue (bone fibers). Scrutiny under the microscope further revealed that the putative dinosaur soft tissue had retained fine structures (microstructures) even at the cellular level. The exact nature and composition of this material, and the implications of Schweitzer's discovery, are not yet clear; study and interpretation of the material is ongoing.<ref name="Schweitzer2005">{{cite journal|author=Schweitzer, M.H., Wittmeyer, J.L. and Horner, J.R.|date=2005|title=Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex|journal=Science|volume=307|issue=5717|pages=1952–1955|doi=10.1126/science.1108397|pmid=15790853}}</ref>

Newer research, published in PloS One (30 July 2008), has challenged the claims that the material found is the soft tissue of ''Tyrannosaurus''. Thomas Kaye of the [[University of Washington]] and his co-authors contend that what was really inside the tyrannosaur bone was slimy [[biofilm]] created by bacteria that coated the voids once occupied by blood vessels and cells.<ref>{{cite journal|year=2008|month=July|title=Dinosaurian Soft Tissues Interpreted as Bacterial Biofilms.|journal=PLoS ONE|volume=3|issue=7|pages=e2808doi=10.1371/journal.pone.0002808|url=http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0002808|accessdate=2008-07-29|doi=10.1371/journal.pone.0002808|url=http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0002808|accessdate=2008-07-29|doi_brokendate=2008-10-08|unused_data=MKaye TG, Gaugler G, Sawlowicz Z}}</ref> The researchers found that what previously had been identified as remnants of blood cells, because of the presence of iron, were actually [[framboid]]s, microscopic mineral spheres bearing iron. They found similar spheres in a variety of other fossils from various periods, including an [[ammonite]]. In the ammonite they found the spheres in a place where the iron they contain could not have had any relationship to the presence of blood.<ref>[http://newswise.com/articles/view/542898/ New Research Challenges Notion That Dinosaur Soft Tissues Still Survive] Newswise, Retrieved on 29 July 2008.</ref>

The successful extraction of ancient DNA from dinosaur fossils has been reported on two separate occasions, but upon further inspection and [[peer review]], neither of these reports could be confirmed.<ref>{{cite journal|author=Wang, H., Yan, Z. and Jin, D.|date=1997|title=Reanalysis of published DNA sequence amplified from Cretaceous dinosaur egg fossil|journal=Molecular Biology and Evolution|volume=14|pages=589–591|url=http://mbe.oupjournals.org/cgi/reprint/14/5/589|accessdate=2007-12-05}}</ref> However, a functional visual [[peptide]] of a theoretical dinosaur has been inferred using analytical phylogenetic reconstruction methods on gene sequences of related modern species such as reptiles and birds.<ref>{{cite journal|author=Chang BS, Jönsson K, Kazmi MA, Donoghue MJ, Sakmar TP|date=2002|title=Recreating a Functional Ancestral Archosaur Visual Pigment|journal=Molecular Biology and Evolution|volume=19|issue=9|pages=1483–1489|pmid=12200476|url=http://mbe.oxfordjournals.org/cgi/content/full/19/9/1483|accessdate=2007-12-05}}</ref> In addition, several [[protein]]s have putatively been detected in dinosaur fossils,<ref>{{cite journal|author=Embery G, Milner AC, Waddington RJ, Hall RC, Langley MS, Milan AM|title=Identification of proteinaceous material in the bone of the dinosaur Iguanodon|journal=Connect Tissue Res|date=2003|volume=44|issue=Suppl 1|pages=41–6|pmid=12952172|doi=10.1080/713713598}}</ref> including hemoglobin.<ref>{{cite journal|author=Schweitzer MH, Marshall M, Carron K, Bohle DS, Busse SC, Arnold EV, Barnard D, Horner JR, Starkey JR|title=Heme compounds in dinosaur trabecular bone|journal=Proc Natl Acad Sci U S A.|date=1997|volume=94|issue=12|pages=6291–6|pmid=9177210|doi=10.1073/pnas.94.12.6291}}</ref>

Even if dinosaur DNA could be reconstructed, it would be exceedingly difficult to clone and "grow" dinosaurs using current technology since no closely related species exist to provide [[zygote]]s or a suitable environment for [[Embryogenesis|embryonic development]].

==Feathers and the origin of birds==
{{main|Origin of birds}}

The possibility that dinosaurs were the ancestors of birds was first suggested in 1868 by [[Thomas Henry Huxley]].<ref name=huxley1868>{{cite_journal |last=Huxley |first=Thomas H. |authorlink=Thomas Henry Huxley |year=1868 |title=On the animals which are most nearly intermediate between birds and reptiles |journal=Annals of the Magazine of Natural History |volume=4 |issue=2 |pages=66–75}}</ref> After the work of [[Gerhard Heilmann]] in the early 20th century, the theory of birds as dinosaur descendants was abandoned in favor of generalized [[thecodont]] ancestors, with the key piece of evidence being the supposed lack of [[clavicle]]s in dinosaurs.<ref name=heilmann>{{cite_book |last=Heilmann |first=Gerhard |year=1926 |title=The Origin of Birds |location=London |publisher=Witherby |pages=208pp}}</ref> However, as later discoveries showed, clavicles (or a single fused [[furcula|wishbone]], which derived from separate clavicles) were not actually absent;<ref name=KP04/> they had been found as early as 1924 in ''Oviraptor'', but misidentified as an [[interclavicle]].<ref name=HO24>{{cite journal |last=Osborn |first=Henry Fairfield |year=1924 |title=Three new Theropoda, ''Protoceratops'' zone, central Mongolia |journal=American Museum Novitates |volume=144 |pages=1–12 |url=http://digitallibrary.amnh.org/dspace/bitstream/2246/3223/1/N0144.pdf |format=pdf}}</ref> In the 1970s, [[John Ostrom]] revived the dinosaur-bird theory,<ref name=ostrom1973>{{cite_journal |last=Ostrom |first=John H. |authorlink=John Ostrom |year=1973 |title=The ancestry of birds |journal=Nature |volume=242 |issue=5393 |pages=136 |doi=10.1038/242136a0}}</ref> which gained momentum in the coming decades with the advent of cladistic analysis,<ref name=gauthier1986>{{cite_book |last=Gauthier |first=Jacques. |authorlink=Jacques Gauthier |year=1986 |chapter=Saurischian monophyly and the origin of birds |editor=Padian, Kevin. (ed.) |title=The Origin of Birds and the Evolution of Flight |series=Memoirs of the California Academy of Sciences '''8''' |pages=1–55}}</ref> and a great increase in the discovery of small theropods and early birds.<ref name=TRHJ00/> Of particular note has been the fossils of the [[Yixian Formation]], where a variety of theropods and early birds have been found, often with feathers of some type.<ref name=KP04/> Birds share over a hundred distinct anatomical features with theropod dinosaurs, which are now generally accepted to have been their closest ancient relatives.<ref>{{cite journal|author=Mayr, G., Pohl, B. and Peters, D.S.|date=2005|title=A Well-Preserved Archaeopteryx Specimen with Theropod Features|journal=Science|volume=310|issue=5753|pages=1483–1486|doi=10.1126/science.1120331|pmid=16322455}}</ref>
They are most closely allied with [[maniraptora]]n coelurosaurs.<ref name=KP04/> A minority of scientists, most notably [[Alan Feduccia]] and [[Larry Martin]], have proposed other evolutionary paths, including revised versions of Heilmann's basal archosaur proposal,<ref name=martin2004>{{cite_journal |last=Martin |first=Larry D. |authorlink=Larry Martin |year=2006 |title=A basal archosaurian origin for birds |journal=Acta Zoologica Sinica |volume=50 |issue=6 |pages=977–990}}</ref> or that maniraptoran theropods are the ancestors of birds but themselves are not dinosaurs, only [[convergent evolution|convergent]] with dinosaurs.<ref name=AF02/>

===Feathers===
{{main|Feathered dinosaurs}}
[[Image:SArchaeopteryxBerlin2.jpg|thumb|210px|right|The famous Berlin Specimen of ''[[Archaeopteryx|Archaeopteryx lithographica]]''.]]

''[[Archaeopteryx]]'', the first good example of a "feathered dinosaur", was discovered in 1861. The initial specimen was found in the [[Solnhofen limestone]] in southern Germany, which is a ''[[Lagerstätten|lagerstätte]]'', a rare and remarkable geological formation known for its superbly detailed fossils. ''Archaeopteryx'' is a [[transitional fossil]], with features clearly intermediate between those of modern reptiles and birds. Brought to light just two years after Darwin's seminal ''[[The Origin of Species]]'', its discovery spurred the nascent debate between proponents of [[evolutionary biology]] and [[creationism]]. This early bird is so dinosaur-like that, without a clear impression of feathers in the surrounding rock, at least one specimen was mistaken for ''[[Compsognathus]]''.<ref name=PW88>{{cite journal|author=Wellnhofer, P|date=1988|title=Ein neuer Exemplar von ''Archaeopteryx''|journal=Archaeopteryx|volume=6|pages=1–30}}</ref>

Since the 1990s, a number of additional [[feathered dinosaurs]] have been found, providing even stronger evidence of the close relationship between dinosaurs and modern birds. Most of these specimens were unearthed in the [[Lagerstätten|lagerstätte]] of the Yixian Formation, [[Liaoning]], northeastern [[China]], which was part of an island continent during the Cretaceous. Though feathers have been found only in a few locations, it is possible that non-avian dinosaurs elsewhere in the world were also feathered. The lack of widespread fossil evidence for feathered non-avian dinosaurs may be due to the fact that delicate features like skin and feathers are not often preserved by [[fossil]]ization and thus are absent from the fossil record. To this point, protofeathers (thin, filament-like structures) are known from dinosaurs at the base of Coelurosauria, such as [[compsognathidae|compsognathids]] like ''[[Sinosauropteryx]]'' and [[tyrannosauroidea|tyrannosauroids]] (''[[Dilong (dinosaur)|Dilong]]''),<ref>{{cite journal|author=Xu X.; Norell, M.A.; Kuang X.; Wang X.; Zhao Q.; and Jia C.|title=Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroids|journal=Nature|date=2004|volume=431|issue=7009|pages=680–684|pmid=15470426 |doi=10.1038/nature02855 }}</ref> but barbed feathers are only known among the coelurosaur subgroup Maniraptora, which includes oviraptorosaurs, troodontids, dromaeosaurids, and birds.<ref name=KP04/><ref name=GC06>{{cite journal |last=Göhlich |first=U.B. |coauthors=and Chiappe, L.M. |year=2006 |title=A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago |journal=Nature |volume=440 |pages=329–332 |doi=10.1038/nature04579}}</ref> The description of feathered dinosaurs has not been without controversy; perhaps the most vocal critics have been Alan Feduccia and Theagarten Lingham-Soliar, who have proposed that protofeathers are the result of the decomposition of collagenous fiber that underlaid the dinosaurs' integument,<ref name=TLS03>{{cite journal |last=Lingham-Soliar |first=T. |year=2003 |title=The dinosaurian origin of feathers: perspectives from dolphin (Cetacea) collagen fibers |journal=Naturwissenschaften |volume=12 |pages=563–567 |pmid=14676953 |doi=10.1007/s00114-003-0483-7 }}</ref><ref name=FLH05>{{cite journal|last=Feduccia |first=A. |coauthors=Lingham-Soliar, T.; and Hinchliffe, J.R. |year=2005 |title=Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence |journal=Journal of Morphology |volume=266 |issue=2 |pages=125–166 |pmid=16217748 |doi=10.1002/jmor.10382 }}</ref><ref name=LSFX07>{{cite journal |last=Lingham-Soliar |first=T. |coauthors=Feduccia, A.; and Wang X. |year=2007 |title=A new Chinese specimen indicates that 'protofeathers' in the Early Cretaceous theropod dinosaur ''Sinosauropteryx'' are degraded collagen fibres |journal=Proceedings of the Biological Sciences |volume=274 |issue=1620 |pages=1823–9 |pmid=17521978 |doi=10.1098/rspb.2007.0352 }}</ref> and that maniraptoran dinosaurs with barbed feathers were not actually dinosaurs, but [[convergent evolution|convergent]] with dinosaurs.<ref name=AF02>{{cite journal |last=Feduccia |first=A. |year=2002 |title=Birds are dinosaurs: simple answer to a complex problem |journal=The Auk |volume=119 |pages=1187–1201 |doi=10.1642/0004-8038(2002)119[1187:BADSAT]2.0.CO;2}}</ref><ref name=FLH05/> However, their views have for the most part not been accepted by other researchers, to the point that the question of the scientific nature of Feduccia's proposals has been raised.<ref>{{cite journal |last=Prum |first=Richard O. |month=April |year=2003 |title=Are Current Critiques Of The Theropod Origin Of Birds Science? Rebuttal To Feduccia 2002 |journal=[[The Auk]] |volume=120 |issue=2 |pages=550–61 |url=http://links.jstor.org/sici?sici=0004-8038(200304)120:2%3C550:ACCOTT%3E2.0.CO;2-0 |doi=10.1642/0004-8038(2003)120[0550:ACCOTT]2.0.CO;2}}</ref>

===Skeleton===
Because feathers are often associated with birds, feathered dinosaurs are often touted as the [[transitional fossil|missing link]] between birds and dinosaurs. However, the multiple skeletal features also shared by the two groups represent another important line of evidence for [[paleontologist]]s. Areas of the skeleton with important similarities include the neck, [[pubis (bone)|pubis]], [[wrist]] (semi-lunate [[carpal]]), arm and [[pectoral girdle]], furcula (wishbone), and [[keel (bird)|breast bone]]. Comparison of bird and dinosaur skeletons through [[cladistics|cladistic analysis]] strengthens the case for the link.

===Soft anatomy===
Large meat-eating dinosaurs had a complex system of air sacs similar to those found in modern birds, according to an investigation which was led by [[Patrick O'Connor (paleontologist)|Patrick O'Connor]] of [[Ohio University]]. The lungs of theropod dinosaurs (carnivores that walked on two legs and had birdlike feet) likely pumped air into hollow sacs in their [[skeleton]]s, as is the case in birds. "What was once formally considered unique to birds was present in some form in the ancestors of birds", O'Connor said.<ref>{{cite journal|author=O'Connor PM & Claessens LPAM|date=2005|title=Basic avian pulmonary design and flow-through ventilation in non-avian theropod dinosaurs|journal=Nature|volume=436|pages=253–256|doi=10.1038/nature03716}}</ref> In a paper published in the online journal Public Library of Science ONE (September 29, 2008), scientists described ''[[Aerosteon|Aerosteon riocoloradensis]]'', the skeleton of which supplies the strongest evidence to date of a dinosaur with a bird-like breathing system. [[computed tomography|CT-scanning]] revealed the evidence of air sacs within the body cavity of the ''Aerosteon'' skeleton.<ref>{{cite journal|year=2008|month=Sept|title=Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina|journal=PLoS ONE|volume=3|issue=9|pages= e3303doi=10.1371/journal.pone.0003303|url=http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0003303|accessdate=2008-09-29|doi=10.1371/journal.pone.0003303|url=http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003303|accessdate=2008-09-29|doi_brokendate=2008-10-08|unused_data=Sereno PC, Martinez RN, Wilson JA, Varricchio DJ, Alcober OA, et al.}}</ref><ref>[http://newswise.com/articles/view/544722/ Meat-Eating Dinosaur from Argentina Had Bird-Like Breathing System] Newswise, Retrieved on September 29, 2008.</ref>

Another piece of evidence that birds and dinosaurs are closely related is the use of [[gizzard]] stones. These stones are swallowed by animals to aid digestion and break down food and hard fibres once they enter the stomach. When found in association with [[fossil]]s, gizzard stones are called [[gastrolith]]s.<ref>{{cite journal|author=Wings O|title=A review of gastrolith function with implications for fossil vertebrates and a revised classification|journal=Palaeontologica Polonica|volume=52|issue=1|pages=1–16|date=2007|url=http://www.app.pan.pl/acta52/app52-001.pdf|accessdate=2007-11-24|format={{dead link|date=June 2008}}{{ndash}} [http://scholar.google.co.uk/scholar?hl=en&lr=&q=intitle%3AA+review+of+gastrolith+function+with+implications+for+fossil+vertebrates+and+a+revised+classification&as_publication=Palaeontologica+Polonica&as_ylo=&as_yhi=&btnG=Search Scholar search]}}</ref>

===Reproductive biology===
A discovery of features in a ''[[Tyrannosaurus|Tyrannosaurus rex]]'' [[skeleton]] recently provided more evidence that dinosaurs and birds evolved from a common ancestor and, for the first time, allowed paleontologists to establish the sex of a dinosaur. When laying eggs, female birds grow a special type of bone in their limbs between the hard outer bone and the [[marrow]]. This ''medullary'' bone, which is rich in [[calcium]], is used to make eggshells. The presence of endosteally-derived bone tissues lining the interior marrow cavities of portions of the ''Tyrannosaurus rex'' specimen's hind limb suggested that ''T. rex'' used similar reproductive strategies, and revealed the specimen to be female.<ref name="schweitzeretal2005">{{cite journal |last=Schweitzer |first=M.H. |coauthors=Wittmeyer, J.L.; and Horner, J.R. |title=Gender-specific reproductive tissue in ratites and ''Tyrannosaurus rex'' |journal=Science |volume=308 |pages=1456–1460|url=http://www.sciencemag.org/cgi/content/abstract/308/5727/1456 |doi=10.1126/science.1112158 |year=2005 | pmid=15933198}}</ref> Further research has found medullary bone in the theropod ''[[Allosaurus]]'' and ornithopod ''[[Tenontosaurus]]''. Because the line of dinosaurs that includes ''Allosaurus'' and ''Tyrannosaurus'' diverged from the line that led to ''Tenontosaurus'' very early in the evolution of dinosaurs, this suggests that dinosaurs in general produced medullary tissue. Medullary bone has been found in specimens of sub-adult size, which suggests that dinosaurs reached sexual maturity rather quickly for such large animals.<ref name=LW08>{{cite journal |last=Lee |first=Andrew H. |coauthors=and Werning, Sarah |year=2008 |title=Sexual maturity in growing dinosaurs does not fit reptilian growth models |journal=Proceedings of the National Academy of Sciences |volume=105 |issue=2 |pages=582–587 |doi=10.1073/pnas.0708903105 |url=http://www.pnas.org/cgi/content/abstract/105/2/582 |pmid=18195356 }}</ref>

===Behavioral evidence===
A recently discovered [[Troodontidae|troodont]] fossil demonstrates that some dinosaurs slept like certain modern birds, with their heads tucked under their arms.<ref>{{cite journal|author=Xu, X. and Norell, M.A.|date=2004|title=A new troodontid dinosaur from China with avian-like sleeping posture|journal=Nature|volume=431|pages=838–841|doi=10.1038/nature02898}}</ref> This behavior, which may have helped to keep the head warm, is also characteristic of modern birds.

==Extinction==
{{main|Cretaceous–Tertiary extinction event|K–T boundary}}

Non-avian dinosaurs suddenly became [[extinct]] approximately 65 million years ago. Many other groups of animals also became extinct at this time, including [[ammonite]]s ([[nautilus]]-like [[mollusk]]s), [[mosasaur]]s, plesiosaurs, pterosaurs, herbivorous [[turtle]]s and [[crocodile]]s, most birds, and many groups of mammals.<ref name="MacLeod">{{cite journal|author=MacLeod, N, Rawson, PF, Forey, PL, Banner, FT, Boudagher-Fadel, MK, Bown, PR, Burnett, JA, Chambers, P, Culver, S, Evans, SE, Jeffery, C, Kaminski, MA, Lord, AR, Milner, AC, Milner, AR, Morris, N, Owen, E, Rosen, BR, Smith, AB, Taylor, PD, Urquhart, E & Young, JR|title=The Cretaceous–Tertiary biotic transition|date=1997|journal=Journal of the Geological Society|volume=154|issue=2|pages=265–292|url=http://findarticles.com/p/articles/mi_qa3721/is_199703/ai_n8738406/print|doi=10.1144/gsjgs.154.2.0265}}</ref> This [[mass extinction]] is known as the [[Cretaceous–Tertiary extinction event]]. The nature of the event that caused this mass extinction has been extensively studied since the 1970s; at present, several related theories are supported by paleontologists. Though the general consensus is that an impact event was the primary cause of dinosaur extinction, some scientists cite other possible causes, or support the idea that a confluence of several factors was responsible for the sudden disappearance of dinosaurs from the fossil record.

At the peak of the Mesozoic, there were no [[polar ice cap]]s, and sea levels are estimated to have been from 100 to 250 meters (300 to 800 ft) higher than they are today. The planet's temperature was also much more uniform, with only 25 °[[Celsius|C]] (45 °[[Fahrenheit|F]]) separating average polar temperatures from those at the equator. On average, atmospheric temperatures were also much warmer; the poles, for example, were 50 °C (90 °F) warmer than today.<ref name="pmid16311326">{{cite journal |author=Miller KG, Kominz MA, Browning JV, Wright JD, Mountain GS, Katz ME, Sugarman PJ, Cramer BS, Christie-Blick N, Pekar SF |title=The Phanerozoic record of global sea-level change |journal=Science |volume=310 |issue=5752 |pages=1293–8 |year=2005 |pmid=16311326 |doi=10.1126/science.1116412}}</ref><ref>{{cite journal|title=Palaeotemperatures, polar ice-volume, and isotope stratigraphy (Mg/Ca, δ18O, δ13C, 87Sr/86Sr): The Early Cretaceous (Berriasian, Valanginian, Hauterivian)|author=McArthura JM, Janssenb NMM, Rebouletc S, Lengd MJ, Thirlwalle MF & van de Shootbruggef B|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|volume=248|issues=3-4|date=2007|pages=391–430|doi=10.1016/j.palaeo.2006.12.015}}</ref>

The atmosphere's composition during the Mesozoic was vastly different as well. Carbon dioxide levels were up to 12 times higher than today's levels, and oxygen formed 32 to 35% of the atmosphere, as compared to 21% today. However, by the late Cretaceous, the environment was changing dramatically. Volcanic activity was decreasing, which led to a cooling trend as levels of atmospheric carbon dioxide dropped. Oxygen levels in the atmosphere also started to fluctuate and would ultimately fall considerably. Some scientists hypothesize that climate change, combined with lower oxygen levels, might have led directly to the demise of many species. If the dinosaurs had respiratory systems similar to those commonly found in modern birds, it may have been particularly difficult for them to cope with reduced respiratory efficiency, given the enormous oxygen demands of their very large bodies.<ref name="MacLeod"/>

===Impact event===
{{main|Chicxulub crater}}
[[Image:Chicxulub radar topography.jpg|thumb|The [[Chicxulub Crater]] at the tip of the [[Yucatán Peninsula]]; the impactor that formed this crater may have caused the dinosaur extinction.]]
The asteroid collision theory, which was brought to wide attention in 1980 by [[Walter Alvarez]] and colleagues, links the [[extinction event]] at the end of the Cretaceous period to a [[bolide]] impact approximately 65.5 million years ago. Alvarez ''et al.'' proposed that a sudden increase in [[iridium]] levels, recorded around the world in the period's rock stratum, was direct evidence of the impact.<ref name=Alvarezetal80>{{cite journal|title=Extraterrestrial cause for the Cretaceous–Tertiary extinction|author=Alvarez, LW, Alvarez, W, Asaro, F, and Michel, HV|date=1980|journal=Science|volume=208|issue=4448|pages=1095–1108|doi=10.1126/science.208.4448.1095|pmid=17783054}}</ref> The bulk of the evidence now suggests that a 5 to 15 kilometer (3 to 9 mi) wide [[bolide]] hit in the vicinity of the [[Yucatán Peninsula]], creating the {{km to mi|170|precision=-1}} wide [[Chicxulub Crater]] and triggering the [[mass extinction]].<ref name=ARHetal91>{{cite journal|author=Hildebrand, Alan R.; Penfield, Glen T.; Kring, David A.; Pilkington, Mark; Zanoguera, Antonio Camargo; Jacobsen, Stein B.; Boynton, William V. |title=Chicxulub Crater; a possible Cretaceous/Tertiary boundary impact crater on the Yucatan Peninsula, Mexico|year=1991|month=September |volume=19|issue=9 |journal=[[Geology (journal)|Geology]]|pages=867–871|url=http://geology.geoscienceworld.org/cgi/content/abstract/19/9/867 |doi=10.1130/0091-7613(1991)019<0867:CCAPCT>2.3.CO;2}}</ref> Scientists are not certain whether dinosaurs were thriving or declining before the [[impact event]]. Some scientists propose that the meteorite caused a long and unnatural drop in Earth's atmospheric temperature, while others claim that it would have instead created an unusual heat wave.

Although the speed of extinction cannot be deduced from the fossil record alone, various models suggest that the extinction was extremely rapid. The consensus among scientists who support this theory is that the impact caused extinctions both directly (by heat from the meteorite impact) and also indirectly (via a worldwide cooling brought about when matter ejected from the impact crater reflected thermal radiation from the sun).

In September of 2007, U.S. researchers led by [[William Bottke]] of the [[Southwest Research Institute]] in [[Boulder, Colorado]], and [[Czech Republic|Czech]] scientists used [[computer]] simulations to identify the probable source of the Chicxulub impact. They calculated a 90% probability that a giant asteroid named [[Baptistina]], approximately {{km to mi|160|precision=-1}} in diameter, orbiting in the asteroid belt which lies between [[Mars]] and [[Jupiter]], was struck by a smaller unnamed asteroid about 55 kilometers (35 mi) in diameter about 160 million years ago. The impact shattered Baptistina, creating a cluster which still exists today as the [[Baptistina family]]. Calculations indicate that some of the fragments were sent hurtling into earth-crossing orbits, one of which was the {{km to mi|10}} wide [[meteorite]] which struck [[Mexico]]'s [[Yucatan]] [[peninsula]] 65 million years ago, creating the [[Chicxulub crater]] ({{km to mi|175|precision=-1}}).<ref name='Billiards'> {{cite journal|title=Solar System: Lethal billiards|journal=Nature|date=2007-09-05|first=Claeys|last=P|coauthors=Goderis, S|volume=449|issue= |pages=30–31|doi=10.1038/449030a|url= |format= |accessdate=}}</ref>

While similar to Alvarez's impact theory (which involved a single asteroid or comet), this theory proposes that "passages of the [[Nemesis (star)|solar companion star Nemesis]] through the [[Oort cloud|Oort comet cloud]] would trigger comet showers."<ref name="Koeberl">{{cite book|date=2002|title=Catastrophic Events and Mass Extinctions|publisher=Geological Society of America|isbn=0-8137-2356-6|author=edited by Christian Koeberl and Kenneth G. MacLeod.|oclc=213836505|unused_data=Koeberl, C & MacLeodKG}}</ref> One or more of these objects then collided with the Earth at approximately the same time, causing the worldwide extinction. As with the impact of a single asteroid, the end result of this comet bombardment would have been a sudden drop in global temperatures, followed by a protracted cool period.<ref name="Koeberl"/>

===Deccan Traps===
{{main|Deccan Traps}}

Before 2000, arguments that the [[Deccan Traps]] [[flood basalt]]s caused the [[extinction]] were usually linked to the view that the extinction was gradual, as the flood basalt events were thought to have started around 68 mya and lasted for over 2 million years. However, there is evidence that two-thirds of the Deccan Traps were created in 1 million years about 65.5 mya, so these eruptions would have caused a fairly rapid extinction, possibly a period of thousands of years, but still a longer period than what would be expected from a single impact event.<ref name = "wwnjsd">{{cite journal|author=Hofman, C, Féraud, G & Courtillot, V|date=2000|title=40Ar/39Ar dating of mineral separates and whole rocks from the Western Ghats lava pile: further constraints on duration and age of the Deccan traps|journal=Earth and Planetary Science Letters|volume=180|pages=13–27|doi=10.1016/S0012-821X(00)00159-X}}</ref><ref name="Duncan">{{cite journal|title=Rapid eruption of the Deccan flood basalts at the Cretaceous/Tertiary boundary|author=Duncan, RA & Pyle, DG|date=1988|journal=Nature|volume=333|pages=841–843|doi=10.1038/333841a0}}</ref>

The Deccan Traps could have caused extinction through several mechanisms, including the release of dust and sulphuric aerosols into the air which might have blocked sunlight and thereby reducing photosynthesis in plants. In addition, Deccan Trap volcanism might have resulted in carbon dioxide emissions which would have increased the [[greenhouse effect]] when the dust and aerosols cleared from the atmosphere.<ref name="Duncan"/> Before the mass extinction of the dinosaurs, the release of [[volcanic gas]]ses during the formation of the [[Deccan traps]] "contributed to an apparently massive [[Global warming#History|global warming]]. Some data point to an average rise in temperature of 8 °C (14 °F) in the last half million years before the [[Chicxulub Crater|impact [at Chicxulub]]]."<ref name = "wwnjsd"/><ref name="Duncan"/>

In the years when the Deccan Traps theory was linked to a slower extinction, [[Luis Alvarez]] (who died in 1988) replied that [[paleontologists]] were being misled by [[Signor-Lipps effect|sparse data]]. While his assertion was not initially well-received, later intensive field studies of fossil beds lent weight to his claim. Eventually, most paleontologists began to accept the idea that the mass extinctions at the end of the Cretaceous were largely or at least partly due to a massive Earth impact. However, even Walter Alvarez has acknowledged that there were other major changes on Earth even before the impact, such as a drop in [[sea level]] and massive volcanic eruptions that produced the Indian Deccan Traps, and these may have contributed to the extinctions.<ref>{{cite book|author=Alvarez, W|title=T. rex and the Crater of Doom|date=1997|publisher=Princeton University Press|isbn=978-0691016306|pages=130–146}}</ref>

===Failure to adapt to changing conditions===
Lloyd ''et al'' (2008) noted that, in the Mid Cretaceous, the flowering [[angiosperm]] plants became a major part of terrestrial [[ecosystem]]s, which had previously been dominated by [[gymnosperm]]s such as conifers. Dinosaur [[coprolite]]s — fossilized dung — indicate that, while some ate angiosperms, most herbivorous dinosaurs mainly ate gymnosperms. Statistical analysis by Lloyd ''et al'' concluded that, contrary to earlier studies, dinosaurs did not diversify very much in the Late Cretaceous. Lloyd ''et al'' suggested that dinosaurs' failure to diversify as ecosystems were changing doomed them to extinction.<ref name="LloydDavisPisaniEtAl2008DinosAndKTR" />

===Possible Paleocene survivors===
Nonavian dinosaur remains are occasionally found above the [[K-T boundary]]. In 2002, paleontologists Zielinski and Budahn reported the discovery of a single [[hadrosauridae|hadrosaur]] leg bone fossil in the San Juan Basin, New Mexico and described it as evidence of [[Paleocene dinosaurs]]. The formation in which the bone was discovered has been dated to the early [[Paleocene]] epoch approximately 64.5 million years ago. If the bone was not re-deposited into that [[stratum]] by weathering action, it would provide evidence that some dinosaur populations may have survived at least a half million years into the Cenozoic Era.<ref name="Fassett">{{cite journal|url=http://www.lpi.usra.edu/meetings/impact2000/pdf/3139.pdf|title=Compelling new evidence for Paleocene dinosaurs in the Ojo Alamo Sandstone, San Juan Basin, New Mexico and Colorado, USA|author=Fassett, JE, Lucas, SG, Zielinski, RA, and Budahn, JR|date=2001|journal=Catastrophic events and mass extinctions, Lunar and Planetary Contribution|volume=1053|pages=45–46|accessdate=2007-05-18}}</ref> Other evidence includes the finding of dinosaur remains in the [[Hell Creek Formation]] up to 1.3 meters (51 in) above (40,000 years later than) the K-T boundary. Similar reports have come from other parts of the world, including China.<ref name="Sloan">{{cite journal|author=Sloan, R. E., Rigby, K,. Van Valen, L. M., Gabriel, Diane|date=1986|title=Gradual dinosaur extinction and simultaneous ungulate radiation in the Hell Creek Formation |journal=Science |volume=232 |issue=4750 |pages=629–633 |url=http://www.sciencemag.org/cgi/content/abstract/232/4750/629|doi=10.1126/science.232.4750.629|accessdate=2007-05-18|pmid=17781415}}</ref> Many scientists, however, dismiss the "Paleocene dinosaurs" as re-worked, i.e. washed out of their original locations and then re-buried in much later sediments,<ref name=FS05>{{cite journal |last=Fastovsky |first=David E. |coauthors=and Sheehan, Peter M. |year=2005 |title=Reply to comment on "The Extinction of the dinosaurs in North America" |journal=GSA Today |volume=15 |pages=11 |url=http://www.gsajournals.org/archive/1052-5173/15/7/pdf/i1052-5173-15-7-11a.pdf |format=pdf |doi=10.1130/1052-5173(2005)015[11b:RTEOTD]2.0.CO;2 }}</ref><ref>{{cite journal|last=Sullivan|first=RM|title=No Paleocene dinosaurs in the San Juan Basin, New Mexico|url=http://gsa.confex.com/gsa/2003RM/finalprogram/abstract_47695.htm|journal=Geological Society of America Abstracts with Programs|volume=35|issue=5|pages=15|date=2003|accessdate=2007-07-02}}</ref> or find that, if correct, the presence of a handful of dinosaurs in the early Paleocene would not change the underlying facts of the extinction.<ref name=FS05/>

==History of discovery==
Dinosaur fossils have been known for millennia, although their true nature was not recognized. The Chinese, whose modern word for dinosaur is ''konglong'' (恐龍, or "terrible dragon"), considered them to be [[Chinese dragon|dragon]] [[bone]]s and documented them as such. For example, ''Hua Yang Guo Zhi'', a book written by Zhang Qu during the [[Western Jin Dynasty]], reported the discovery of dragon bones at Wucheng in [[Sichuan]] Province.<ref>{{cite book|author=[[Dong Zhiming]]|year=1992|title=Dinosaurian Faunas of China|publisher=China Ocean Press, Beijing|isbn=3-540-52084-8|oclc=26522845}}</ref> Villagers in central China have been digging up dinosaur bones for decades, thinking they were from dragons, to make traditional medicine.<ref>{{cite web|last= |first= |authorlink= |coauthors= |title=Dinosaur bones 'used as medicine' |work= |publisher=BBC News|date=2007|url=http://news.bbc.co.uk/2/hi/asia-pacific/6276948.stm|format= |doi= |accessdate=2007-07-06}}</ref> In Europe, dinosaur fossils were generally believed to be the remains of [[Giant (mythology)|giants]] and other creatures killed by the [[Deluge (mythology)|Great Flood]].

[[Image:William Buckland detail.png|thumb|left|130px|[[William Buckland]].]]
''[[Megalosaurus]]'' was the first dinosaur to be formally described, in 1677, when part of a bone was recovered from a [[limestone]] [[quarry]] at Cornwell near [[Chipping Norton, Oxfordshire|Chipping Norton]], [[Oxfordshire]], [[England]]. This bone fragment was identified correctly as the lower extremity of the [[femur]] of an animal larger than anything living in modern times. The second dinosaur genus to be identified, ''[[Iguanodon]]'', was discovered in 1822 by Mary Ann Mantell - the wife of English geologist [[Gideon Mantell]]. Gideon Mantell recognized similarities between [http://collections.tepapa.govt.nz/objectdetails.aspx?oid=212194&coltype=history&regno=gh004839 his fossils] and the bones of modern [[iguana]]s. Two years later, the Rev [[William Buckland]], a professor of [[geology]] at [[University of Oxford|Oxford University]], unearthed more fossilized bones of ''Megalosaurus'' and became the first person to describe dinosaurs in a [[scientific journal]].<ref name=WAS97>{{cite book |last=Sarjeant |first=William A.S. |editor=Farlow, James O.; and Brett-Surman, Michael K. (eds.) |title=The Complete Dinosaur |year=1997 |publisher=Indiana University Press |location=Bloomington |isbn=0-253-33349-0 |pages=3–11 |chapter=The earliest discoveries }}</ref>

The study of these "great fossil lizards" soon became of great interest to European and American scientists, and in 1842 the English paleontologist [[Richard Owen]] coined the term "dinosaur". He recognized that the remains that had been found so far, ''Iguanodon'', ''Megalosaurus'' and ''[[Hylaeosaurus]]'', shared a number of distinctive features, and so decided to present them as a distinct taxonomic group. With the backing of [[Prince Albert of Saxe-Coburg-Gotha]], the husband of [[Victoria of the United Kingdom|Queen Victoria]], Owen established the [[Natural History Museum]] in [[South Kensington]], [[London]], to display the national collection of dinosaur fossils and other biological and geological exhibits.

In 1858, the first known American dinosaur was discovered, in [[marl]] pits in the small town of [[Haddonfield, New Jersey]] (although fossils had been found before, their nature had not been correctly discerned). The creature was named ''[[Hadrosaurus]] foulkii''. It was an extremely important find; ''Hadrosaurus'' was one of the first nearly complete dinosaur skeletons found and it was clearly a [[bipedal]] creature. ([[Iguanodon#Gideon_Mantell.2C_Sir_Richard_Owen.2C_and_the_discovery_of_dinosaurs|The first]] was in 1834, in Maidstone, Kent, England) This was a revolutionary discovery as, until that point, most scientists had believed dinosaurs walked on four feet, like other lizards. Foulke's discoveries sparked a wave of dinosaur mania in the [[United States]].

[[Image:OthnielCharlesMarsh.jpg|left|thumb|130px|[[Othniel Charles Marsh]], 19th century photograph.]]
[[Image:edcope.jpg|130px|right|thumb|[[Edward Drinker Cope]], 19th century photograph.]]

Dinosaur mania was exemplified by the fierce rivalry between [[Edward Drinker Cope]] and [[Othniel Charles Marsh]], both of whom raced to be the first to find new dinosaurs in what came to be known as the [[Bone Wars]]. The feud probably originated when Marsh publicly pointed out that Cope's reconstruction of an ''[[Elasmosaurus]]'' skeleton was flawed; Cope had inadvertently placed the [[plesiosaur]]'s head at what should have been the animal's tail end. The fight between the two scientists lasted for over 30 years, ending in 1897 when Cope died after spending his entire fortune on the dinosaur hunt. Marsh 'won' the contest primarily because he was better funded through a relationship with the [[US Geological Survey]]. Unfortunately, many valuable dinosaur specimens were damaged or destroyed due to the pair's rough methods; for example, their diggers often used [[dynamite]] to unearth bones (a method modern paleontologists would find appalling). Despite their unrefined methods, the contributions of Cope and Marsh to paleontology were vast; Marsh unearthed 86 new species of dinosaur and Cope discovered 56, for a total of 142 new species. Cope's collection is now at the [[American Museum of Natural History]] in [[New York]], while Marsh's is on display at the [[Peabody Museum of Natural History]] at [[Yale University]].<ref>{{cite book|author=Holmes T|title=Fossil Feud: The Bone Wars of Cope and Marsh, Pioneers in Dinosaur Science|date=1996|publisher=Silver Burdett Press|isbn=978-0382391477|oclc=34472600}}</ref>

Since 1897, the search for dinosaur fossils has extended to every continent, including [[Antarctica]]. The first Antarctic dinosaur to be discovered, the [[ankylosaur]]id ''[[Antarctopelta|Antarctopelta oliveroi]]'', was found on [[Ross Island]] in 1986, although it was 1994 before an Antarctic species, the theropod ''[[Cryolophosaurus ellioti]]'', was formally named and described in a scientific journal.

Current dinosaur "hot spots" include southern South America (especially [[Argentina]]) and [[China]]. China in particular has produced many exceptional [[feathered dinosaur]] specimens due to the unique geology of its dinosaur beds, as well as an ancient arid climate particularly conducive to [[fossil]]ization.

===The "dinosaur renaissance"===
{{main|Dinosaur renaissance}}
The field of dinosaur research has enjoyed a surge in activity that began in the 1970s and is ongoing. This was triggered, in part, by [[John Ostrom]]'s discovery of ''[[Deinonychus]]'', an active predator that may have been [[warm-blooded]], in marked contrast to the then-prevailing image of dinosaurs as sluggish and [[cold-blooded]]. [[Vertebrate paleontology]] has become a global [[science]]. Major new dinosaur discoveries have been made by paleontologists working in previously unexploited regions, including [[India]], South America, [[Madagascar]], [[Antarctica]], and most significantly in [[China]] (the amazingly well-preserved [[feathered dinosaurs]] in [[China]] have further consolidated the link between dinosaurs and their conjectured living descendants, modern birds). The widespread application of [[cladistics]], which rigorously analyzes the relationships between biological organisms, has also proved tremendously useful in [[scientific classification|classifying]] dinosaurs. Cladistic analysis, among other modern techniques, helps to compensate for an often incomplete and fragmentary [[fossil record]].

==Cultural depictions==
{{main|Cultural depictions of dinosaurs}}
[[Image:London - Crystal Palace - Victorian Dinosaurs 1.jpg|right|thumb|170px|A ''[[Megalosaurus]]'' stalks [[Crystal Palace Park]] in [[London]].]]
By human standards, dinosaurs were creatures of fantastic appearance and often enormous size. As such, they have captured the public imagination and become an enduring part of human culture. Only three decades after the first scientific descriptions of dinosaur remains, the famous [[Crystal Palace dinosaurs|dinosaur sculptures]] were erected in [[Crystal Palace Park]] in [[London]]. These sculptures excited the public so strongly that smaller replicas were sold, one of the first examples of [[tie-in]] [[merchandising]]. Since Crystal Palace, dinosaur exhibitions have opened at parks and [[Museum#Natural history museums|museums]] around the world, both catering to, and reinforcing, the public interest.<ref name="torrens1993">{{cite journal|author=Torrens, H.S.|date=1993|title=The dinosaurs and dinomania over 150 years|journal=Modern Geology|volume=18|issue=2|pages=257–286}}</ref> Dinosaur popularity has long had a reciprocal effect on dinosaur science, as well. The competition between museums for public attention led directly to the [[Bone Wars]] waged between Marsh and Cope, each striving to return with more spectacular fossil remains than the other, and the resulting contribution to dinosaur science was enormous.<ref name="breithaupt1997">{{cite book|author=Breithaupt, Brent H.|date=1997|title=First golden period in the USA." In: Currie, Philip J. & Padian, Kevin (Eds.). ''The Encyclopedia of Dinosaurs''|publisher=University of California Press|pages=347–350|isbn=978-0122268106}}</ref>

Dinosaurs hold an integral place in modern culture. The word "dinosaur" itself has entered the English [[lexicon]] as an expression describing anything that is impractically large, slow-moving, or obsolete, bound for extinction.<ref name="m-w">"[http://www.m-w.com/dictionary/dinosaur Definition of dinosaur]" Merriam-Webster's Online Dictionary. Accessed 26 May 2007.</ref> The public preoccupation with dinosaurs led to their inevitable entrance into worldwide [[popular culture]]. Beginning with a passing mention of ''Megalosaurus'' in the first paragraph of [[Charles Dickens]]' ''[[Bleak House]]'' in 1852,<ref name="bleakhouse">"''London. Michaelmas term lately over, and the Lord Chancellor sitting in Lincoln's Inn Hall. Implacable November weather. As much mud in the streets, as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborne Hill.''" From page 1 of Dickens, Charles J.H. (1852). ''Bleak House''. London: Bradbury & Evans.</ref> dinosaurs have been featured in a broad array of [[fiction]]al works. [[Sir Arthur Conan Doyle]]'s 1912 book ''[[The Lost World (Arthur Conan Doyle)|The Lost World]]'', the iconic 1933 [[motion picture|film]] ''[[King Kong (1933 film)|King Kong]]'', the 1954 introduction of ''[[Godzilla (1954 film)|Godzilla]]'' and its many subsequent sequels, the best-selling 1990 novel ''[[Jurassic Park]]'' by [[Michael Crichton]] and its 1993 [[Jurassic Park (film)|film version]], briefly the [[List of highest-grossing films|highest-grossing film of all time]], are just a few prominent examples of the long tradition of dinosaurs in fiction. [[Non-fiction]] authors, including some prominent paleontologists, have also sought to take advantage of dinosaur popularity, especially among children, to educate readers about dinosaurs in particular and science in general. Dinosaurs are ubiquitous in [[advertising]], with numerous [[Company (law)|companies]] seeking to utilize dinosaurs to sell their own products or to characterize their rivals as slow-moving or obsolete.<ref name=DFGlut1997>{{cite book|author=Glut, DF, & Brett-Surman, MK|date=1997|title=Dinosaurs and the media." In: Farlow, James O. & Brett-Surman, Michael K. (Eds.). ''The Complete Dinosaur''|publisher=Indiana University Press|pages=675–697|isbn=978-0253213136}}</ref>

==Religious views==
{{main|Young Earth Creationism#Palaeontology and dinosaurs}}
Various religious groups have views about dinosaurs that differ from those held by the vast majority of scientists, usually due to conflicts with [[Creationism|creation stories]] in their scriptures. However, most of the [[Scientific method|scientific]] community rejects these religiously-inspired interpretations of dinosaurs.<ref name="Kitcher">{{cite book|last=Kitcher|first=Philip|authorlink= |coauthors= |title=Abusing Science: The Case Against Creationism|publisher=MIT Press|date=1983|location= |pages=213|url=http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=5383|doi= |isbn=978-0-262-61037-7 }}</ref><ref name="Dawkins">{{cite book|last=Dawkins|first=Richard|authorlink= |coauthors= |title=The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe Without Design|publisher=W.W. Norton|date=1996|location= |pages=400|url= |doi= |isbn=978-0393315707}}</ref>

==See also==
{{seealsosection
|commons=Dinosauria
|portal=Dinosaurs}}
* [[Dinosaur classification]]
* [[Physiology of dinosaurs]]
* [[Fossil]]s
* [[List of dinosaurs]]
* [[List of dinosaur-bearing rock formations]]
* [[Prehistoric life]]
* [[Prehistoric reptile]]s

==Notes and references==
{{reflist|colwidth=45em}}

==General references==
<div class="references-small">
* Kevin Padian, and Philip J. Currie. (1997). ''Encyclopedia of Dinosaurs''. Academic Press. ISBN 0-12-226810-5. (Articles are written by experts in the field).
* [[Gregory S. Paul|Paul, Gregory S.]] (2000). ''The Scientific American Book of Dinosaurs''. St. Martin's Press. ISBN 0-312-26226-4.
*Paul, Gregory S. (2002). ''Dinosaurs of the Air: The Evolution and Loss of flight in Dinosaurs and Birds''. Baltimore: The Johns Hopkins University Press. ISBN 0-8018-6763-0.
*[[David B. Weishampel|Weishampel, David B.]] (2004). ''The Dinosauria''. University of California Press; 2nd edition. ISBN 0-520-24209-2.
</div>

==External links==

{{Spoken Wikipedia|Dinosaur.ogg|2005-12-30}}


;Images

*[http://skeletaldrawing.com/ Skeletal Drawing] Professional restorations of numerous dinosaurs, and discussions of dinosaur anatomy.

;Popular
*[http://www.nhm.ac.uk/nature-online/life/dinosaurs-other-extinct-creatures/index.html Dinosaurs & other extinct creatures]: From the [[Natural History Museum]], a well illustrated dinosaur directory.

*[http://www.dinosaurnews.org/ Dinosaurnews] (''www.dinosaurnews.org'') The dinosaur-related headlines from around the world. Recent news on dinosaurs, including finds and discoveries, and many links.
*[http://www.ucmp.berkeley.edu/diapsids/dinosaur.html Dinosauria] From UC Berkeley Museum of Paleontology Detailed information - scroll down for menu.
*[http://www.livescience.com/dinosaurs/ LiveScience.com] All about dinosaurs, with current featured articles.
*[http://www.dinoruss.com/ Dino Russ's Lair] hosts a large collection of dinosaur-related links.
*[http://www.enchantedlearning.com/subjects/dinosaurs/ Zoom Dinosaurs] (''www.enchantedlearning.com'') From Enchanted Learning. Kids' site, info pages and stats, theories, history.
*[http://www.geol.umd.edu/~tholtz/dinoappendix/DinoappendixSummer2008.pdf Dinosaur genus list] contains data tables on nearly every published dinosaur genus.

;Technical
*[http://palaeo-electronica.org/ ''Palaeontologia Electronica''] From Coquina Press. Online technical journal.
*[http://dinobase.gly.bris.ac.uk Dinobase] A searchable dinosaur database, from the University of Bristol, with dinosaur lists, classification, pictures, and more.
*[http://www.dinodata.org/index.php DinoData] (''www.dinodata.org'') Technical site, essays, classification, anatomy.
*[http://www.dinosauria.com/dml/dml.htm Dinosauria On-Line] (''www.dinosauria.com'') Technical site, essays, pronunciation, dictionary.
*[http://www.users.qwest.net/~jstweet1/ Thescelosaurus!] By Justin Tweet. Includes a cladogram and small essays on each relevant genera and species.
*[http://www.palaeos.com/Vertebrates/Units/Unit310/000.html Dinosauromorpha Cladogram] From [http://www.Palaeos.com Palaeos]. A detailed amateur site about all things paleo.
*[http://www.dinoruss.com/de_4/dino30.htm The Dinosaur Encyclopaedia], an extensive overview of genera-based dinosaur information from 1999 and before.

{{featured article}}

{{Archosauromorpha}}

[[Category:Dinosaurs| ]]
[[Category:Paleontology]]
[[Category:Paleozoology]]
[[Category:Greek loanwords]]

{{Link FA|sl}}
{{Link FA|th}}
{{Link FA|es}}
{{Link FA|hu}}
{{Link FA|zh}}

[[ar:ديناصور]]
[[an:Dinosauria]]
[[ast:Dinosauriu]]
[[bn:ডাইনোসর]]
[[zh-min-nan:Khióng-liông]]
[[map-bms:Dinosaurus]]
[[bs:Dinosaurusi]]
[[br:Dinosaor]]
[[bg:Динозаври]]
[[ca:Dinosaure]]
[[cs:Dinosauři]]
[[cy:Deinosor]]
[[da:Dinosaurus]]
[[de:Dinosaurier]]
[[et:Dinosaurused]]
[[el:Δεινόσαυρος]]
[[es:Dinosauria]]
[[eo:Dinosaŭro]]
[[eu:Dinosauro]]
[[fa:دایناسور]]
[[fo:Dinosaurur]]
[[fr:Dinosaure]]
[[gan:恐龍]]
[[gl:Dinosauro]]
[[zh-classical:恐龍]]
[[hak:Khiúng-liùng]]
[[ko:공룡]]
[[hi:डायनोसोर]]
[[hr:Dinosauri]]
[[id:Dinosaurus]]
[[is:Risaeðlur]]
[[it:Dinosauria]]
[[he:דינוזאורים]]
[[jv:Dinosaurus]]
[[ka:დინოზავრები]]
[[sw:Dinosau]]
[[ku:Dînezor]]
[[la:Dinosauria]]
[[lv:Dinozauri]]
[[lt:Dinozaurai]]
[[li:Dinosaurusse]]
[[hu:Dinoszaurusz]]
[[ml:ഡൈനസോര്‍]]
[[ms:Dinosaur]]
[[nl:Dinosauriërs]]
[[ja:恐竜]]
[[no:Dinosaurer]]
[[nn:Dinosaurus]]
[[oc:Dinosaures]]
[[pa:ਡਾਯਨੋਸੋਰ]]
[[pl:Dinozaury]]
[[pt:Dinossauros]]
[[ro:Dinozaur]]
[[rm:Dinosaurs]]
[[qu:Dinusawru]]
[[ru:Динозавры]]
[[scn:Dinusauru]]
[[simple:Dinosaur]]
[[sk:Dinosaury]]
[[sl:Dinozavri]]
[[sr:Диносауруси]]
[[su:Dinosaurus]]
[[fi:Dinosaurukset]]
[[sv:Dinosaurier]]
[[tl:Dinosauro]]
[[ta:தொன்மா]]
[[te:డైనోసార్]]
[[th:ไดโนเสาร์]]
[[vi:Khủng long]]
[[tr:Dinozor]]
[[uk:Динозаври]]
[[ur:حیوان المہیب]]
[[yi:דיינעסאר]]
[[zh-yue:恐龍]]
[[bat-smg:Dinuozaurā]]
[[zh:恐龙]]

Young Earth Creationism

2008-10-22T22:39:58Z

ReaganFan0101:

{{Creationism2}}
[[Image:Durer Adam and Eve.jpg|thumb|right|Adam and Eve, the first human beings according to [[Genesis]].]]

'''Young Earth creationism''' (YEC) is the religious belief that [[Heaven]], [[Earth]], and [[life on Earth]] were created by a direct act of [[God]] dating [[Dating Creation|between 6,000<ref name = "Griffiths"/> and 10,000 years ago]].
Its adherents are those [[Christian]]s and [[Jew]]s who believe that [[God]] created the Earth in six 24-hour days, taking the [[Hebrew Bible|Hebrew]] text of [[Genesis (Hebrew Bible)|Genesis]] as a [[Biblical literalism|literal account]]. Some adherents believe that existing evidence in the natural world today supports a strict interpretation of scriptural creation as historical fact. Those adherents believe that the scientific evidence supporting [[evolution]], [[Geology|geological]] [[uniformitarianism]], or other theories which are at odds with a literal interpretation of the [[Creation according to Genesis|Genesis creation account]], is either flawed or misinterpreted.<ref>{{cite web |url=http://www.thefirstsixdays.com |title=The First Six Days (of Creation): Confronting the God-Plus-Evolution Myth |accessdate=2007-08-25 |format= |work=}}</ref>

Many Young Earth creationists (YECs) are active in the development of [[creation science]], an endeavor that holds that the events associated with supernatural creation can be evidenced and modelled through an interpretation of the [[scientific method]]. This has led to the establishment of a number of Young Earth Creation Science organizations such as the [[Institute for Creation Research]] and the [[Creation Research Society]].

YECs claim that the lack of support for a Young Earth theory in professional science journals or among professional science organizations is due to discrimination and censorship.<ref>{{cite web|url=http://www.answersingenesis.org/docs2005/0822sternberg.asp|title=The Smithsonian/Sternberg controversy|author=Sheppard, P|year=2005|publisher=[http://www.answersingenesis.org Answers in Genesis]|accessdate=2007-07-03}}</ref><ref>{{cite web|url=http://www.answersingenesis.org/docs2005/0822sternberg.asp|title=Do Creationists Publish in Notable Refereed Journals?|author=Buckna, D|year=2007|publisher=[http://www.answersingenesis.org Answers in Genesis]|accessdate=2007-07-03}}</ref><ref>{{cite web|url=http://worldnetdaily.com/news/article.asp?ARTICLE_ID=53400|title=Congress slams Smithsonian's anti-religious attacks|year=2006|author=Unruh, B|accessdate=2007-07-03}}</ref><ref>{{cite web|url=http://www.discovery.org/scripts/viewDB/index.php?command=view&id=3833&program=DI%20Main%20Page%20-%20News&callingPage=discoMainPage|title=US Congressional Committee Report: INTOLERANCE AND THE POLITICIZATION OF SCIENCE AT THE SMITHSONIAN|year=2006|author=United States House of Representatives Committee on Government Reform|publisher=[http://www.discovery.org The Discovery Institute]|accessdate=2007-07-03}}</ref> However, the overwhelming [[scientific consensus]] is that YEC claims have no scientific basis. For example, a statement by 68 national and international [[Academy of Sciences|science academies]] lists the following as evidence-based facts, established by numerous observations and independently derived experimental results from a multitude of scientific disciplines, without any contradiction from scientific evidence: that the Earth is approximately 4.5 billion years old and has shown continuing change; that life appeared on Earth at least 2.5 billion years ago, and has subsequently taken many forms, all of which continue to evolve; and that the genetic code of all organisms living today, including humans, clearly indicates their common primordial origin.<ref>{{cite web|url=http://www.interacademies.net/Object.File/Master/6/150/Evolution%20statement.pdf|title=IAP Statement on the teaching of evolution|year=2006|publisher=the Interacademy Panel on international issues|accessdate=2007-07-03|format=PDF}}</ref>

== History ==
=== Origins ===

Some YECs have claimed that this view has its earliest roots in Judaism, citing, for example, the commentary on Genesis by [[Abraham ibn Ezra|Ibn Ezra]] (c. 1089–1164).<ref name="Griffiths">{{ cite journal | title=Creation days and Orthodox Jewish tradition | last=James-Griffiths | first=P|journal=Creation|volume=26|issue=2|pages=53–55| url=http://www.answersingenesis.org/creation/v26/i2/tradition.asp|accessdate=2007-07-03}}</ref> However, Shai Cherry of [[Vanderbilt University]] notes that Jewish theologians have generally rejected such literalist interpretations of the written text, and that even Jewish commentators who oppose some aspects of Darwinian thought generally accept scientific evidence that the Earth is much older.<ref>{{cite book|author=Cherry, S|title=Crisis management via Bilbical Interpretation: Fundamentalism, Modern Orthodoxy, and Genesis in Jewish Tradition and the Challenge of Darwinism (Cantor, G Swetlitz, M, editors|publisher=University of Chicago Press|year=2006|isbn=978-0226092775}}</ref> Similar claims are made of Christian commentators, but a number of prominent early [[Christianity|Christian]] [[Church Fathers]] including [[Justin Martyr]], [[Clement of Alexandria]], [[Origen]], and [[Augustine of Hippo|Augustine]], did not believe the Genesis account depicted ordinary solar days and read [[Allegorical interpretations of Genesis|creation history as an allegory]] as well as being theologically true (however this being said, all of these men certainly ''did'' believe in a young earth<ref>Origen: < 10,000 years, Celsus, 1.20; Augustine: < 5,600 years, City 12.11; Eusebius: 5,228 years, Chronicle; Clement 5,592 years, Miscellanies 1.21</ref>). The [[Protestant reformation]] [[hermeneutic]] inclined some of the Reformers and later Protestants toward a literal reading of the Bible as translated, believing in an ordinary day, and maintaining this younger-Earth view.

The belief that the universe was made by a rational Creator was held by many of the founders of modern science, such as [[Nicolaus Copernicus|Copernicus]], [[Johannes Kepler|Kepler]], [[Michael Faraday|Faraday]], [[Galileo Galilei|Galileo]], [[James Clerk Maxwell|Maxwell]], [[Isaac Newton|Newton]], [[Robert Boyle|Boyle]], [[Blaise Pascal|Pascal]] and [[Nicolas Steno]], all of whom followed the empirical [[Baconian method]] described by [[Francis Bacon]] (1561 – 1626), who emphasised that the works of God in nature teach us how to interpret the word of God in the Bible.<ref name="moore">{{cite web | last = Moore | first = James | authorlink = James Moore (biographer) | title = Evolution and Wonder - Understanding Charles Darwin | work = Speaking of Faith (Radio Program) | publisher = American Public Media | url =http://speakingoffaith.publicradio.org/programs/darwin/transcript.shtml | accessdate = 2007-06-27 }}</ref>

In [[1650]], [[Archbishop Ussher]] published the [[Ussher chronology]], a chronology dating the [[Creation according to Genesis|creation]] to the night preceding [[October 23]] [[4004 BC]]. Ussher's proposed date of 4004 BC differed little from [[Dating Creation#Date of Creation according to the Pentateuch|other Biblically-based estimates]], such as those of [[Bede]] (3952 BC), Ussher's near-contemporary, [[Joseph Justus Scaliger|Scaliger]] (3949 BC), [[Johannes Kepler]] (3992 BC), [[Sir Isaac Newton]] (c. 4000 BC), or [[John Lightfoot]] (3929 BC).

=== Decline ===

Support for YEC declined from the 18th century onwards with the development of the [[scientific revolution]], and scientific [[paradigm shift]]s. Findings in geology led to a number of explanations which required an ancient Earth, such as [[Abraham Gottlob Werner]]'s [[Neptunism]]. [[James Hutton]], now regarded as the father of modern geology, went further and opened up the concept of [[deep time]] for scientific inquiry. Rather than accepting that the Earth was deteriorating from a primal state, he maintained that the Earth must be much older (indeed, he asserted that the Earth was infinitely old). Hutton stated that "the past history of our globe must be explained by what can be seen to be happening now … No powers are to be employed that are not natural to the globe, no action to be admitted except those of which we know the principle."<ref>'Theory of the Earth', a paper (with the same title of his 1795 book) communicated to the Royal Society of Edinburgh, and published in ''Transactions of the Royal Society of Edinburgh'', 1785; cited with approval in Holmes, A., ''Principles of Physical Geology'', 2nd edition, Thomas Nelson and Sons Ltd., Great Britain, pp. 43–44, 1965.</ref>

Hutton's main line of argument was that the tremendous displacements and changes he was seeing did not happen in a short period of time by means of catastrophe, but that the incremental processes of uplift and erosion happening on the Earth in the present day had caused them. As these processes were very gradual, the Earth needed to be ancient, in order to allow time for the changes to occur. While his ideas of [[Plutonism]] were hotly contested, scientific inquiries on competing ideas of [[catastrophism]] pushed back the age of the Earth into the millions of years — still much younger than commonly accepted by modern scientists, but a great change from the literalist view of an Earth that was only a few thousand years old.<ref>[http://www.uwmc.uwc.edu/geography/hutton/hutton.htm ''Theory of the Earth''] full text (1788 version)</ref>

Hutton's ideas, called [[Uniformitarianism (science)|uniformitarianism]], or [[Gradualism]] were popularized by Sir [[Charles Lyell]] in the early 19th century. The energetic advocacy of Lyell led to the public and scientific communities largely accepting an ancient Earth. By this time the Reverends [[William Buckland]], [[Adam Sedgwick]] and other early geologists had abandoned their earler ideas of catastrophism related to a Biblical flood and confined their explanations to local floods. By the 1830s, mainstream science had abandoned YEC as a serious hypothesis. It became therefore important for biblical scholars as well as Christian scientists to harmonize the [[Genesis]] account with new scientific results into a 'new geology'.<ref>[http://evolution.berkeley.edu/evolibrary/article/_0/history_12 Uniformitarianism: Charles Lyell], University of California Museum of Paleontology</ref>

John H Mears was one such scholar who proposed several theories varying from a mix of long/indefinite periods with moments of creation to a day-age theory of indefinite 'days'. He subscribed to the latter theory (indefinite days) and found support from the side of [[James Dwight Dana]], Professor at Yale and one of the fathers of [[Mineralogy]] who wrote a paper consisting of 4 articles named 'Science and the Bible' on the topic.<ref name="Dana">{{cite book | last = Dana, Phd. Professor at Yale | first = James Dwight | title = Science and the Bible, a review of and the six days of creation of Prof. Lewis Taylor | publisher = Bibl. Soc. | year = 1856-1857}} URL: [http://www.farlang.com/gemstones/dana-science-bible/page_001 Prof. James Dwight Dana, Science and the Bible, online version] </ref> With the acceptance by many biblical scholars of a reinterpretation of Genesis 1 in the light of the breakthrough results of Lyell and supported by a number of renowned (christian) scientific scholars, a new hurdle was taken in the future acceptance of Developmentalism (based on Darwin's Natural selection). <ref>{{cite web | url = http://www.bible.org/page.php?page_id=2054#P52_10723 | title = Bible.org, Darwinism and New England Theology | year = 2004 | accessdate = 2007-07-08 }}</ref>

In the 20th century, many religious groups abandoned (Young Earth) creationism as a literal description of the Earth's history altogether and came to regard the biblical account of creation in [[Genesis]] as purely allegorical or mythological.{{Fact|date=April 2008}}

=== Revival ===
The rise of [[fundamentalist Christianity]] at the start of the twentieth century saw a revival of interest in YEC, as a part of their rejection of the explanation of [[evolution]].{{Fact|date=August 2008}} In 1923, [[George McCready Price]], a [[Seventh-day Adventist Church|Seventh-day Adventist]] wrote ''The New Geology'', a book partly inspired by the book ''Patriarchs and Prophets'' in which [[Seventh-day Adventist Church|Seventh-day Adventist]] prophet [[Ellen G. White]] described the impact of the [[Great Flood (Biblical)|Great flood]] on the shape of the Earth. Although not an accredited geologist, Price's writings, which were based upon reading geological texts and documents, rather than field or laboratory work,<ref>The Creationists (Expanded Edition), p92, 106 [[Ronald Numbers]], 2006</ref> provide an explicitly fundamentalist perspective on geology. The book attracted only a small following, with its advocates almost all being Lutheran pastors and Seventh-day Adventists in America.<ref name="rsf">{{cite book|author=Marston, P & Forster, R| year=2001| title=Reason Science and Faith| publisher=Monarch Books| isbn =978-1579106614| url=http://www.ivycottage.org/group/group.aspx?id=6826| accessdate =2007-06-30}}</ref> [[Harry Rimmer]] was another prominent exponent of similar views, at least during some of his evangelizing career (Rimmer appears to have also subscribed to "[[gap creationism]]", and a local flood, at least at some times).

In the 1950’s, Price's work came under severe criticism, particularly by [[Bernard Ramm]] in his book ''The Christian View of Science and Scripture''. Together with [[J. Laurence Kulp]], a geologist and in fellowship with the [[Plymouth Brethren]],and other scientists<ref>[http://www.asa3.org/ASA/PSCF/1993/PSCF12-93Yang.html Radiocarbon Dating and American Evangelical Christians]</ref>, Ramm influenced Christian organisations such as the [[American Scientific Affiliation]] (ASA) in not supporting [[flood geology]].

Price's work was subsequently adapted and updated by [[Henry M. Morris]] and [[John C. Whitcomb]] Jr. in their book ''[[The Genesis Flood]]'' in 1961. Morris and Whitcomb argued that the Earth was geologically recent and that the [[Great Flood]] had laid down most of the geological strata in the space of a single year, reviving pre-Uniformitarian arguments. Given this history, they argued, "the last refuge of the case for evolution immediately vanishes away, and the record of the rocks becomes a tremendous witness... to the holiness and justice and power of the living God of Creation!"<ref>Whitcomb, JC (1960). The Genesis Flood: The Biblical Record and Its Scientific Implications. P&R Publishing. ISBN 978-0875523385</ref>

This became the foundation of a new generation of YEC thinkers, who organized themselves around Morris' [[Institute for Creation Research]]. Sister organizations such as the [[Creation Research Society]] have sought to re-interpret geological formations within a YEC viewpoint. [[Langdon Brown Gilkey|Langdon Gilkey]] writes,

<blockquote>... no distinction is made between scientific theories on the one hand and philosophical or religious theories on the other, between scientific questions and the sorts of questions religious beliefs seek to answer... It is, therefore, no surprise that in their theological works, as opposed to their creation science writings, creationists regard evolution and all other theories associated with it, as the intellectual source for and intellectual justification of everything that is to them evil and destructive in modern society. For them all that is spiritually healthy and creative has been for a century or more under attack by "that most complex of godless movements spawned by the pervasive and powerful system of evolutionary uniformitarianism", "If the system of flood geology can be established on a sound scientific basis... then the entire evolutionary cosmology, at least in its present neo-Darwinian form, will collapse. This in turn would mean that every anti-Christian system and movement ([[communism]], [[racism]], [[humanism]], [[libertarianism]], [[behaviorism]], and all the rest) would be deprived of their pseudo-intellectual foundation", "It [evolution] has served effectively as the pseudo-scientific basis of [[atheism]], [[agnosticism]], [[socialism]], [[fascism]], and numerous faulty and dangerous philosophies over the past century"<ref>(Gilkey, 1998, p. 35; quotations from Henry Morris).</ref></blockquote>

Morris' ideas had a considerable impact on creationism and fundamentalist Christianity. Armed with the backing of conservative organizations and individuals, his brand of "[[creation science]]" was widely promoted throughout the [[United States]] and overseas, with his books being translated into at least ten different languages.

In 1978, the International Council on Biblical Inerrancy developed the [[Chicago Statement on Biblical Inerrancy]] which included the following:

<blockquote>WE DENY that Biblical infallibility and inerrancy are limited to spiritual, religious, or redemptive themes, exclusive of assertions in the fields of history and science. We further deny that scientific hypotheses about Earth history may properly be used to overturn the teaching of Scripture on creation and the flood.<ref>{{cite web|url=http://www.bible-researcher.com/chicago1.html|title=Chicago Statement on Biblical Inerrancy with Exposition|year=1978|publisher=Bible Research|accessdate=2007-07-03}}</ref></blockquote>

As of 2008 a [[Gallup]] poll indicated that 50% of US adults agreed with the statement "human beings developed over millions of years from less advanced forms of life." Whereas 44% of US adults agreed with the statement "God created human beings pretty much in their present form at one time within the last 10,000 years."<ref>[ http://www.pollingreport.com/science.htm Gallup Poll. May 8-11, 2008. N=1,017 adults nationwide. MoE ± 3.]</ref>

The revival of YEC has had a periodic impact on science education, particularly in the United States, where periodic controversies have raged over the appropriateness of teaching YEC doctrine and creation science in public schools (see [[Teach the Controversy]]) side by side with the theory of [[evolution]].

YEC has failed to make an impact in more liberal circles of Christianity. For example, the Articles of Faith of the Baptist Church states no required beliefs concerning creation.<ref>[http://www.answersincreation.org/denomination.htm Church Denominations, Creation Science]</ref> Some Churches, such as the [[Roman Catholic Church]], accept the possibility of [[theistic evolution]] but despite this, some individual church members support YEC.<ref>{{cite web |url=http://www.catholicintl.com/scienceissues/dialogue-evolution1.htm |title=Dialogue on Evolution versus Creationism |accessdate=2007-10-10 |author=Philip Porvaznik |publisher=Catholic Apologetics International}} </ref>

===Oriental Orthodox Church===

YEC has always been the stated position of the [[Oriental Orthodox Church]], without having gone through any decline and revival. Fr. Tadros Y. Malaty, a Coptic Orthodox scholar, expresses the typical Oriental Orthodox view as follows:

<blockquote>
Using mathematical calculations, man cannot be more than 6,000 years old. Assuming that every family had three children (a low number compared to previous centuries) and after accounting for natural death catastrophes and wars, we find that the world's population would approximate what it actually is now. If human history goes back a million years, then the world's population would have needed several times the land space we have now.<ref>Fr. Tadros Y. Malaty, ''Commentary on the Book of Genesis'' (1998) p. 22.</ref>
</blockquote>

== Characteristics and beliefs ==
===Age of the Earth===
YECs believe that the Earth is "young", on the order of 6,000 to 10,000 years old,<ref>[http://www.earthage.org/youngearthev/evidence_for_a_young_earth.htm Evidence for a young Earth]</ref> rather than the [[Age of the Earth|age of 4.6 billion years]] calculated by modern [[geology]] using [[geochronology|geochronological]] methods including [[radiometric dating]]. YECs typically derive their range of figures using the ages given in the [[genealogies of Genesis|genealogies]] and other dates in the [[Bible]], similar to the process used by [[James Ussher]] (1581–1656), [[Church of Ireland Archbishop of Armagh]] and [[Primate of All Ireland]], when he dated creation at [[5th millennium BC|4004 BC]]. [[Ussher chronology|Ussher's chronology]], published in 1650, has been subsequently revised many times, most recently in 2003 by Larry and Marion Pierce.<ref>{{cite web|url=http://www.answersingenesis.org/creation/v26/i1/archbishop.asp|title=Archbishop’s achievement|publisher=[[Answers in Genesis]]|author=Jonathan Sarfati}}</ref>

YECs believe that life was created by God [[created kind|'each after their kind']] in the universe's first six normal-length (24-hour) days. Additionally, they believe that the biblical account of [[Noah|Noah's flood]] is historically true, maintaining that there was a worldwide flood (circa 2349 BC) that destroyed all terrestrial life except that which was saved on [[Noah's Ark]]. (Barry Setterfield proposed in 1999 that the flood occurred much earlier around 3536 BC.) They assert that this global flood caused a multitude of geological features that scientists regard as evidence of an old Earth.

=== Attitude towards science ===

YEC is normally characterized as opposing [[evolution]], though it also opposes many claims and theories in the fields of [[physics]] and [[chemistry]] (especially absolute dating methods), [[geology]], [[astronomy]], [[cosmology]], [[molecular biology]], [[genomics]], [[linguistics]], [[anthropology]], [[archaeology]] and any other fields of science that have developed theories or made claims incompatible with the Young Earth version of world history. YECs are fundamentally opposed to any explanation for the origins of anything which replaces God as the universal creator as stated in the Bible, whether it be the origins of biological diversity, the origins of life or the origins of the universe itself. This has led some YECs to criticize [[intelligent design]], a proposal which some see as an alternative form of creationism, for not taking a stand on the age of the Earth, special creation, or even the identity of the designer. Some YECs see this as too compromising.<ref>{{cite web|title=AiG’s views on the Intelligent Design Movement|url=http://www.answersingenesis.org/docs2002/0830_IDM.asp|author=Carl Wieland|date=30 August 2002|publisher=[[Answers in Genesis]]}}</ref>

YECs challenge the [[methodological naturalism]] of the [[scientific method]], which they conflate with [[philosophical naturalism]], and [[uniformitarianism (science)|uniformitarianism]] as the dominant principles of the scientific community. They assert instead that available physical evidence best supports original catastrophism and a young Earth. See [[Creation-evolution controversy]] for a more complete discussion.

=== View of the Bible ===

YECs regard the Bible as a historically accurate, factually [[Biblical inerrancy|inerrant]] record of natural history. They accept its authority as the central organizing text for human life — the sole indisputable source of knowledge on every topic with which it deals. As [[Henry M. Morris|Henry Morris]], a leading YEC, explained it, Christians who flirt with less-than-literal readings of biblical texts are also flirting with theological disaster.<ref name="Morris Conflict">{{cite book|title=The Long War Against God: The History and Impact of the Creation/Evolution Conflict|author=Morris, HM|year=2000|publisher=Master Books|isbn=978-0890512913}}</ref><ref>{{cite book|author=Morris, HM|title=Biblical Creationism: What Each Book of the Bible Teaches About Creation & the Flood|year=2000|publisher=Master Books|isbn=978-0890512937}}</ref> For the vast majority of YECs, an [[Allegorical interpretations of Genesis|allegorical reading]] of the [[Creation according to Genesis|Genesis accounts of Creation]], the [[Fall of man|Fall]], the [[Noah's ark|Deluge]], and the [[Tower of Babel]] would undermine core Christian doctrines like the birth and resurrection of [[Jesus|Jesus Christ]]. According to Morris, Christians must "either ... believe God's Word all the way, or not at all."<ref name="Morris Conflict" />Therefore, YECs take the account of Genesis to be a historical account of the origin of the Earth and life. The corollary is that many YECs regard Christians who do not regard [[Genesis]] as historically accurate as being inconsistent.

=== Interpretation of Genesis ===

YECs interpret the text of Genesis in a strictly literal fashion. Therefore, they believe that God created the world in six normal-length days, and planted below the [[Firmament]] the [[Garden of Eden]] for the habitation of an original human couple ([[Adam and Eve]]). As a result of the subsequent [[Fall of Man]], humanity was forced to work hard to provide food, childbirth became painful, and physical death entered the world. Some YECs assert that prior to the Fall all animals were herbivores (see below).

The [[Genealogies of Genesis]] record the line of descent from Adam through [[Noah]] to [[Abraham]]. YECs interpret these genealogies literally, including the old ages of the men; up to Methuselah who lived 969 years. Differences of opinion exist regarding whether the genealogies should be taken as complete or abbreviated, hence the 6,000 to 10,000 year range usually quoted for the Earth's age. Proponents of [[Old Earth Creationism]], tend to interpret the genealogies as incomplete, and usually interpret the days of Genesis 1 figuratively as long periods of time.

YECs believe that the [[Great Flood (Biblical)|great flood]] described in Genesis 6-9 was global in extent, and submerged the highest mountains on Earth. A range of suggestions are made to account for the mechanism for such a deluge. Earlier generations (following the lead of Morris and Whitcomb) believed that an orbiting [[vapor canopy]] collapsed, generating extreme rainfall (from "windows of heaven"). In more recent times it has been proposed that radical geological activity (the opening of the "fountains of the great deep") was largely responsible for the flood — elaborate theories such as [[Catastrophic plate tectonics]] and [[hydroplates]] have been put forward by some. These theories have the added benefit of explaining how the flood transformed an originally flatter Earth, raising up mountains and dropping sea beds; this then solves the problem of finding sufficient water to cover [[Mount Everest]]. Whatever the case, almost all YECs refer to a loosely codified idea called "[[Flood geology]]" to argue that the vast majority of present-day geological features are the result of the Great Flood.

To support their belief in a worldwide flood, YECs argue that anthropological evidence supports their belief that every culture studied has, in its history, a myth or story similar to that of Noah in two aspects: 1) the occurrence of a catastrophic flood and 2) human and animal life saved by a man who built a large boat and took aboard it for the duration of the flood enough life to repopulate the Earth.{{Fact|date=June 2007}} According to Genesis, two of every "unclean" kind of animal (male and female) and seven of every "clean" kind of animal were placed on the ark during the flood.

After the flood, Genesis reports increasingly shortened lifespans dropping quickly from an average of 900 years at the time of [[Noah]] to an average of 100 by the time of [[Abraham]]. Some YECs have suggested that this is due to effects associated with [[inbreeding]] that took place after the flood, as only eight people remained.<ref>{{cite web|url=http://www.answersingenesis.org/creation/v20/i4/years.asp|author=Carl Wieland|title=Living for 900 years|publisher=[[Answers in Genesis]]}}</ref> Another theory{{Fact|date=February 2008}} suggests that the [[Earth]] had a higher concentration of [[oxygen]] prior to the Flood, possibly due to a layer of water vapor ("[[vapor canopy]]") above the [[Earth]]. The result of such a postulation would be a giant [[Hyperbaric Chamber]], extending lifespans. Others hypothesize that the "[[firmament]]" of the "waters above" screened the Earth from harmful [[ultraviolet]] rays, which they argue, shorten [[life expectancy]].

=== Human history ===

In keeping with a strictly literal interpretation of Genesis, YECs believe that [[Adam and Eve]] were the universal ancestors of the entire human race; accordingly it is usually held that their sons and daughters married amongst themselves to produce the next generation of children.<ref>{{cite web|url=http://www.answersingenesis.org/Home/Area/Tools/cains_wife.asp|title=Cain’s wife — who was she?|publisher=[[Answers In Genesis]]}}</ref> [[Noah's flood]] is supposed to have killed all humans on Earth with the exception of Noah and his sons and their wives. All humans alive today are therefore believed to be descended from this single family, which carried the [[gene pool]] for the entire human race. In contradiction to what is accepted by [[anthropology|anthropologists]], YECs assert that [[Indigenous peoples of the Americas|native Americans]], [[Australian aborigines]] and all other races arose from the migration of people around the world following the [[Tower of Babel]] event in the [[3rd millennium BC]].

Genealogies in the Genesis text identify individuals named [[Egypt]], [[Gomer]], [[Sheba]], [[Canaan]], and [[Sidon]], who are said to have founded the cities and civilizations that were later to bear their names.

=== Animal behavior ===

YECs usually interpret [[Genesis]] to teach that prior to the [[Fall of man]] there was no predatory or [[carnivore|carnivorous activity]] amongst animals, and animals did not die. It is thought that all animals, together with humans, subsisted on an entirely vegetarian diet.<ref>{{cite web|title=Creation’s original diet and the changes at the Fall|publisher=[[Answers in Genesis]]|url=http://www.answersingenesis.org/tj/v5/i2/diet.asp}}</ref> This raises the question of what was the original (i.e. pre-Fall) function of such things as snake venom and spiders webs. YECs typically answer these questions either by postulating a non-lethal original purpose for these predatory mechanisms (eg. snake venom was designed to soften fruit), or suggesting that these mechanisms were miraculously added to animals by God or the [[devil]] at the time of the Fall.<ref>{{cite web|url=http://www.answersingenesis.org/home/area/faq/bad_things.asp|title=How did bad things come about?|publisher=[[Answers in Genesis]]}}</ref>

The implication of these ideas - that before the Fall animals would eventually exceed the [[carrying capacity]] of the Earth - is not considered a problem by some YECs since they believe that the Earth did not remain in its unfallen state for any (generationally) appreciable time.<ref name="Grudem">Wayne A. Grudem "Systematic Theology: An Introduction to Biblical Doctrine", Zondervan, 1996. ISBN 0-3102-8670-0</ref>

=== Diversification of life ===

YECs also assert that all modern species of land vertebrates are descended from those [[created kind|original animals on the ark]]. Most YECs believe that the Ark "kinds" diversified as they subsequently adapted to their environments by the process of variation and rapid natural selection. The selection of such animals as kangaroo and koalas on the ark is based upon hypothesized sunken land bridges between Australia and South East Asia, over which Noah or his sons, or the ancestors of the animals themselves, could travel. Many YECs assert that the process of variation and natural selection resulted in a net ''loss'' of genetic information.{{Fact|date=September 2008}}

=== Palaeontology and dinosaurs ===
The significance of this issue to YECs has its roots in a biblical interpretation of the fall of man that results in sin bringing death into the world, not just for mankind but for all creatures.<ref>{{cite web|last=Ham|first=Ken|last2= and others|url=http://www.answersingenesis.org/home/Area/AnswersBook/dinosaurs19.asp|title=What happened to the dinosaurs?|accessdate=2007-03-14}}</ref>

The term "dinosaur" was first used by [[Richard Owen]] in 1842. As it is a modern coinage derived from Greek, the Bible does not use the word "dinosaur", but the [[Hebrew language|Hebrew]] word ''tanniyn'' ({{IPA|/tan·ˈnin/}}) has been interpreted as referring to them by some Christians.<ref name="clarifying">{{cite web|url=http://www.clarifyingchristianity.com/dinos.shtml|title=Dinosaurs and the Bible|publisher=Clarifying Christianity'|year=2005|accessdate=2007-03-14}}</ref> In English translations, ''tanniyn'' may be translated as “sea monster” or “serpent”, but it is usually translated as “dragon”. These creatures are mentioned close to thirty times in the [[Old Testament]], where they are encountered both on land and in the water.

The Old Testament also describes a huge creature called a "[[behemoth]]" (Job 40:15-24) that "moves his tail like a cedar"; the behemoth is described as ranking "first among the works of God" and as impossible to capture (vs. 24). Some Biblical scholars identify the behemoth as either an [[elephant]], a [[hippopotamus]], or a [[cattle|bull]], but as these animals have very thin tails that are not comparable to the size of a [[cedar]] tree, [[creationists]] often identify the behemoth as a [[sauropod]] dinosaur. Other creationists refer to "behemoth" as a ''[[Brachiosaurus]]'', since the Bible says in Job: "He is the chief of the ways of God", suggesting he is the largest animal God created.<ref name="clarifying">{{cite web|url=http://www.clarifyingchristianity.com/dinos.shtml|title=Dinosaurs and the Bible|publisher=Clarifying Christianity'|year=2005|accessdate=2007-03-14}}</ref> However, others postulate that the reference to the cedar tree actually refers to its needle-like leaves, which resemble the bristly hair present on the tails of modern elephants, rhinoceroses, and hippopotamuses.<ref name="BOTF">{{cite book | author= Bright, Michael | title=Beasts of the Field: The Revealing Natural History of Animals in the Bible | year=2006 | pages= p346 | id=1861058314 }}</ref> Other critics contend that the word "tail" is a euphemism for the animal's [[penis]], and that the passage should be understood as describing its virility.<ref name="isbn0-262-66165-9">{{cite book |author=Pennock, Robert T. |title=Tower of Babel: the evidence against the new creationism |publisher=MIT Press |location=Cambridge, Mass |year=2000 |pages= |isbn=0-262-66165-9 |oclc= |doi=}}</ref><ref>{{cite web |url=http://www.talkorigins.org/indexcc/CH/CH711.html |title=CH711: Behemoth a Dinosaur |accessdate=2007-09-13 |format= |work=}}</ref>

[[Image:Zuiyo Maru.jpg|thumb|250px|Carcass found by the ''[[Zuiyo Maru]]'', said to be a plesiosaur-like creature by some creationists; scientists who have studied it concluded that the remains belong to a [[basking shark]].]]

The [[Leviathan]] is another creature referred to in the Bible's Old Testament; it is described as having a variety of dinosaur, dragon, and water-serpent-like characteristics. Some scholars identify the Leviathan in Job c. 41 with the [[nile crocodile]], others point out that it has seven heads and suggest it is purely mythical. As with the behemoth, creationists have sometimes tried to connect the Leviathan with dinosaurs.<ref>{{cite web|url=http://www.talkorigins.org/indexcc/CH/CH711_1.html|title=Claim CH711.1: Leviathan as a dinosaur|publisher=the TalkOrigins Archive|accessdate=2007-03-14}}</ref>

One view proposed by some is that the serpent in the [[Garden of Eden]] may have actually been a type of dinosaur.<ref>{{cite web |url=http://www.totheends.com/dino.html |title=To The Ends Of The Earth--Dinosaurs in the Bible |accessdate=2007-09-14 |format= |work=}}</ref> They point out that, according to Christian interpretation, God was speaking to the Devil when he cursed the serpent, not to an ordinary snake.

YECs do not deny the existence of [[dinosaur]]s and other extinct animals present in the [[fossil record]].<ref>{{cite web|url=http://www.answersingenesis.org/Docs/2.asp|title=Dinosaurs and the Bible|publisher=Answers in Genisis|accessdate=2007-12-23}}</ref><ref>{{cite web|url=http://www.washingtonpost.com/wp-dyn/content/article/2005/09/24/AR2005092401262.html|title=In Evolution Debate, Creationists Are Breaking New Ground|publisher=The Washington Post}}</ref> Usually, they assert that the fossils represent the remains of animals that perished in the Great Flood. Most believe that Noah took the dinosaurs with him in his Ark<ref>{{cite web|url=http://www.abc.net.au/news/stories/2007/05/27/1934224.htm|title=Dinosaurs were on Noah's Ark: US museum|publisher=ABC News (Australia)|accessdate=2007-11-06}}</ref>, and that they gradually became extinct as a result of a vastly different post-flood environment.<ref>[http://www.answersingenesis.org/articles/nab/what-happened-to-the-dinosaurs What Really Happened to the Dinosaurs? - Answers in Genesis]</ref> The newly-established [[Creation Museum]] in [[Kentucky]] portrays humans and dinosaurs co-existing before the Flood. For many years, YECs referred to supposed associated human and dinosaur tracks in the Paluxy Riverbed of [[Glen Rose, Texas|Glen Rose]], [[Texas]] as proof of coexistence, though most now have abandoned these "[[man track controversy]]" claims, as careful scrutiny has shown them to be either fabrications or spurious phenomena.<ref name=Humanist>{{cite journal
| last = Edwords
| first = Frederick
| authorlink = Fred Edwords
| title = Seeing the Light
| journal = The Humanist
| volume = 46
| issue = 2
| pages = 33–34
| publisher = [[American Humanist Association]]
| date = March/April 1986
| issn = 0018-7399
}}</ref>

Some creationists assert that [[living dinosaurs]] (as well as other extinct creatures such as [[plesiosaur]]s) still survive in isolated spots, accounting for alleged sightings of lake and [[sea monster]]s.<ref>[http://www.drdino.com/articles.php?spec=115 Creation Science Evangelism - Creation, Evolution, Dinosaurs, and the Bible]</ref> Other creationists urge caution about alleged plesiosaurs living today, since rotting [[basking sharks]] can form a pseudo-plesiosaur shape.<ref>[http://www.answersingenesis.org/tj/v13/i2/sharks.asp Letting rotting sharks lie]</ref> Creationists sometimes turn to [[cryptozoology]] to support the idea that creatures known from fossils lived alongside humans in historical times.

YECs occasionally claim that dinosaurs survived in [[Australia]], and that [[Indigenous Australians|Aboriginal]] legends of reptilian monsters are evidence of this,<ref>{{cite web|url=http://www.answersingenesis.org/creation/v21/i1/aborigines.asp|title=Australia’s Aborigines ... did they see dinosaurs?|first=Rebecca|last=Driver|publisher=Answers in Genesis|accessdate=2007-03-14}}</ref> referring to what is known as ''[[Megalania]]'' (''Varanus priscus''). However, ''Megalania'' was a gigantic [[monitor lizard]], and not a dinosaur, as its discoverer, Richard Owens, realized.

== Comparison with other forms of creationism ==

YEC is only one of several forms of creationism. YECs typically oppose these alternative theories, which they consider to be as "compromises" with science<ref>[http://www.answersingenesis.org/home/area/faq/compromise.asp Get Answers: Creation Compromises]</ref> or otherwise flawed.

=== Old Earth creationism ===
{{see also|Old Earth creationism}}

YECs reject [[Old Earth creationism]] and [[Day-Age Creationism]] on textual and theological grounds. In addition, they claim the scientific data in geology and astronomy point to a young Earth, against the consensus of the general scientific community.

YECs generally hold that when Genesis describes the creation of the Earth occurring over a period of days, this indicates normal-length 24 hour days, and cannot reasonably be interpreted otherwise. They agree that the Hebrew word for "day" (''yôm'') can refer to either a 24-hour day or a long or unspecified time, but argue that whenever the latter interpretation is used it includes a preposition defining the long or unspecified period. In the ''specific context of Genesis 1'', since the days are both numbered and are referred to as "evening and morning", this can mean only normal-length days. Further, they argue that the 24-hour day is the only interpretation that makes sense of the [[Shabbat|Sabbath]] command in [[Exodus]] 20:8–11. YECs argue that it is a glaring [[exegesis|exegetical]] [[fallacy]] to take a meaning from one context (yom referring to a long period of time in Genesis 1) and apply it to a completely different one (yom referring to normal-length days in Exodus 20).<ref>[http://www.answersingenesis.org/creation/v19/i1/days.asp How long were the days of Genesis 1?]</ref>

Further, YECs argue that their position is the only way to explain the [[Fall (religion)|Fall]], which introduced death and suffering into the world. They argue that all long-age views entail death before sin, which they regard as a severe theological error, violating [[Genesis]] 3, and for Christians, [[Epistle to the Romans|Romans]] 5:12–19, 8:17–22 and [[1 Corinthians]] 15:21–22.<ref>[http://www.answersingenesis.org/docs2005/0221plant_death.asp The Fall: a cosmic catastrophe]</ref>. Further discussion and refutation of these objections can be found on the [[Day-Age Creationism]] page.

=== Gap creationism ===
{{see also|Gap creationism}}

The "gap theory" acknowledges a vast age for the universe, including the Earth and solar system, while asserting that life was created recently in six 24-hour days by divine fiat. Genesis 1 is thus interpreted literally, with an indefinite "gap" of time inserted between the first two verses. (Some gap theorists insert a "primordial creation" and [[Lucifer]]'s rebellion into the gap.)

Most YEC organizations reject the gap theory, and say it is unscriptural, unscientific, and not necessary, in its various forms.<ref>{{cite web
| title=The gap theory — an idea with holes?
| author=Henry M. Morris
| month=December | year=1987
| url=http://www.answersingenesis.org/creation/v10/i1/gaptheory.asp
| accessdate = 2007-02-14
}}</ref><ref>{{cite web
| title=‘Soft’ gap sophistry
| author=Don Batten
| month=June | year=2004
| url=http://www.answersingenesis.org/creation/v26/i3/softgap.asp
| accessdate = 2007-02-14
}}</ref> It is asserted that the entire universe is only thousands of years old.

=== The ''Omphalos'' hypothesis ===
{{see also|Omphalos hypothesis}}

Many YECs distinguish their own hypotheses from the "Omphalos hypothesis", today more commonly referred to as the apparent age concept, put forth by the naturalist and science writer [[Philip Henry Gosse]]. [[Omphalos (book)|Omphalos]] was an unsuccessful mid-19th century attempt to reconcile creationism with geology. Gosse proposed that just as [[Adam and Eve|Adam]] had a [[navel]] (''omphalos'' is Greek for navel), evidence of a [[gestation]] he never experienced, so also the Earth was created ''[[ex nihilo]]'' complete with evidence of a prehistoric past that never actually occurred. The Omphalos hypothesis allows for a young Earth without giving rise to any predictions that would contradict scientific findings of an old Earth. Although both logically unassailable and consistent with a literal reading of Scripture, Omphalos was rejected at the time by scientists on the grounds that it was completely [[falsifiability|unfalsifiable]] and by theologians because it implied to them a deceitful God, which they found theologically unacceptable.

Most YECs today argue that Adam did ''not'' have a [[navel]],<ref>[http://www.answersingenesis.org/creation/v18/i3/bellybutton.asp Did Adam have a belly-button?]</ref> and in contrast to Gosse, posit that not only is the Earth young but the scientific data supports that view. However, the apparent age concept is still used in YEC literature.<ref>[http://www.apologeticspress.org/articles/1674 Apologetics Press - Apparent Age]</ref><ref>[http://www.don-lindsay-archive.org/creation/apparent_age.html The Apparent Age Argument]</ref><ref>[http://www.asa3.org/ASA/education/origins/aa.htm Appearance of Age - theology overview & web-links]</ref>

== Criticism ==
===Scientific===
YEC was abandoned as a mainstream scientific concept around the start of the 19th century.<ref>{{cite web |url=http://www.mala.bc.ca/~johnstoi/darwin/sect2.htm |title=History of Science: Early Modern Geology|accessdate=2007-09-24 |format= |work=}}</ref> Many scientists see it as a faith position, and regard attempts to prove it scientifically as being little more than religiously motivated [[pseudoscience]]. In 1997, a poll by the Gallup organization showed that 5% of US adults with professional degrees in science took a YEC view. In the aforementioned poll 40% of the same group said that they believed that life, including humans, had evolved over millions of years, but that [[God]] guided this process; a view described as [[theistic evolution]], while 55% held a view of "naturalistic evolution" in which God took no part in this process.<ref name="gallup 1997">{{cite web|url=http://www.religioustolerance.org/ev_publi.htm|title=Gallup Poll 1997}}</ref> Some scientists who believe in creationism are known to subscribe to other forms such as [[Old Earth creationism]] which posits an act of creation that took place millions or billions of years ago, with variations on the timing of the creation of mankind. [[Kent Hovind]] commented on discussing the topic of people asking, "Couldn't God use Evolution to create?" He gives the answer, "Well, it wouldn't be the God of the Bible! The "god" that would use an evolutionary process is cruel, and wasteful, and retarded! Doesn't he know what He wants? Can't He just make it right in six days?"{{Citequote|date=August 2008}}

Critics argue that every challenge to evolution by YECs is either made in an unscientific fashion, or is readily explainable by science, and that while a gap in scientific knowledge may exist now it is likely to be closed through further research. While scientists acknowledge that there are indeed a number of gaps in the scientific theory, they generally reject the creationist viewpoint that these gaps represent fatal, insurmountable flaws with evolution. Those working in the field who pointed out the gaps in the first place have often explicitly rejected the creationist interpretation. The "[[God of the gaps]]" viewpoint has also been criticized by [[theology|theologians]], although creationists claim that their models are based on what is known, not on gaps in knowledge.

Christian YECs adhere strongly to the concept of [[biblical inerrancy]], which declares the Bible to be divinely inspired and therefore scientifically infallible and non-correctable. This position is considered by devotees and critics alike to be incompatible with the principles of scientific [[Objectivity (philosophy)#Epistemic objectivity|objectivity]]. The creationist organizations [[Answers in Genesis]] (AiG) and [[Institute for Creation Research]] (ICR) require all members to pledge support for biblical inerrancy.

YECs often suggest that supporters of evolution theory are primarily motivated by [[atheism]]. Critics reject this claim by pointing out that many supporters of evolutionary theory are in fact religious believers, and that major religious groups such as the [[Roman Catholic Church]] and [[Church of England]] believe that the concept of biological evolution does not imply a rejection of the scriptures. Nor do they support the specific doctrines of biblical inerrancy proposed by YEC. Critics also point out that workers in fields related to evolutionary biology are not required to sign statements of belief in evolution comparable to the biblical inerrancy pledges required by [[Institute for Creation Research|ICR]] and [[Answers in Genesis|AiG]]. This is contrary to the popular belief of creationists that scientists operate on an [[A priori and a posteriori (philosophy)|a priori]] disbelief in biblical principles<ref>[http://www.answersingenesis.org/creation/v20/i3/admission.asp Amazing admission]</ref>. They also discount Christian faith positions, like those of French Jesuit priest, geologist and paleontologist [[Pierre Teilhard de Chardin]], who saw that his work with evolutionary sciences actually confirmed and inspired his faith in the cosmic Christ. Nor do they believe the views of Catholic priest Fr. [[Thomas Berry]], a cultural historian and eco-theologian, that the [[cosmology|cosmological]] 13 billion year "Universe Story" provides all faiths and all traditions a single account by which the divine has made its presence in the world.

Proponents of YEC are regularly accused of [[quote mining]], the dishonest practice of isolating passages from academic texts that appear to support their claims while deliberately excluding context and conclusions to the contrary.<ref>[http://www.talkorigins.org/faqs/quotes/mine/project.html Quote Mine Project: Examining 'Evolution Quotes' of Creationists]</ref>

=== Theological ===

Some theologians oppose the proposition that God can be a legitimate or viable subject for scientific experimentation, and reject a literal interpretation of Genesis. They propose there are statements in the creation week itself which render the historical interpretation of [[Genesis]] incompatible with [[scientific evidence]].

One example is that God created the Earth and heavens, and light, on Day 1, plant life on Day 3, and the sun and moon on Day 4. One must ask where the light in Day 1 came from, and why there were plants in Day 3 if the sun, which provides all light to the Earth, did not even exist until Day 4.<ref>[http://www.answersingenesis.org/articles/am/v2/n2/framework-interpretation-critique-part-one A Critique of the Framework Interpretation of the Creation Account (Part 1 of 2) - Answers in Genesis]</ref> YECs such as [[Basil the Great]] and [[John Calvin]] answered this by suggesting that the light created by God on Day 1 was the light source. [[Answers in Genesis]] has refined this by suggesting that the Earth was already rotating with respect to this light.<ref>[http://www.answersingenesis.org/docs/1203.asp How could the days of Genesis 1 be literal before the sun was created?]</ref> One can also make a case that God created the plants toward the evening of Day 3, the Sun was created on the morning of Day 4, therefore the plants only had to endure darkness for a period not much longer than a typical night.

Another problem is the fact that distant galaxies can be seen. If the universe did not exist until 10,000 years ago, then light from anything farther than 10,000 light-years would not have time to reach us. Most cosmologists accept an inflation model as the likely explanation for the horizon problem. Inflationary models also account for other phenomena, and are in agreement with observations of recent microwave anisotropy satellites. Creationists have also proposed models to explain why we see distant starlight.<ref>[http://www.answersingenesis.org/creation/v25/i4/lighttravel.asp Light-travel time: a problem for the big bang]</ref><ref>[http://www.answersingenesis.org/docs/405.asp Does Distant Starlight Prove the Universe Is Old? - Answers in Genesis]</ref> See [[creationist cosmologies]] for more information.

Many critics claim that Genesis itself is internally inconsistent on the question of whether man was created before the animals ({{bible|Genesis 2:19}}) or after the animals as stated in Genesis 1. Proponents of the [[Documentary hypothesis]] suggest that Genesis 1 was a [[litany]] from the ''[[Priestly source|Priestly]]'' source (possibly from an early Jewish [[liturgy]]) while Genesis 2 was assembled from older ''[[Jahwist]]'' material, holding that for both stories to be a single account, Adam would have named all the animals, and God would have created Eve from his rib as a suitable mate, all within a single 24 hour period. Many creationists attribute this view to misunderstanding having arisen from poor translation of the tenses in Genesis 2 in contemporary translations of the Bible (e.g. compare "planted" and "had planted" in [http://www.biblegateway.com/passage/?search=Gen%202:8;&version=9 KJV] and [http://www.biblegateway.com/passage/?search=Gen%202:8;&version=31 NIV]).<ref>http://www.answersingenesis.org/creation/v16/i1/genesis.asp Biblical Exegesis</ref>
Some Christians assert that the Bible is free from error only in religious and moral matters, and that where scientific questions are concerned, the Bible should not be read literally. This position is held by a number of major denominations. For instance, in a publication entitled ''The Gift of Scripture''<ref>http://www.catholic-ew.org.uk/liturgy/Resources/Scripture/ (October 2005)</ref>, the [[Roman Catholic Church in England and Wales]] comments that "We should not expect to find in Scripture full scientific accuracy or complete historical precision". The Bible is held to be true in passages relating to human salvation, but "We should not expect total accuracy from the Bible in other, secular matters."<ref>[http://www.timesonline.co.uk/article/0,,13509-1811332,00.html Catholic Church no longer swears by truth of the Bible - Times Online]</ref> However, that view of the inerrancy of scripture was rejected by [[Paul VI]] in the formulation of [[Dei Verbum]] 11 forcing the commission to adjust the wording and add crucial footnotes to keep it in line with prior teaching. The relater then said that it was not to be understood as limiting biblical inerrancy to only matters of salvation. However that view has since become predominant due to the deliberate decision to interpret it in a heterodox manner regardless of what it was truly asserting.{{Syn|date=March 2008}}{{Clarifyme|date=March 2008}} By contrast, YECs contend that moral and spiritual matters in the Bible are intimately connected with its historical accuracy; in their view, the Bible stands or falls as a single indivisible block of knowledge.<ref>[http://www.answersingenesis.org/creation/v26/i4/editorial.asp ‘But Genesis is not a science textbook’]</ref>

While some theologians believe there is an inherent conflict between the Bible and science, popular Christian thought holds to the value of science in understanding the physical world. In this view the Bible serves to give understanding about God and the state of mankind (of which the accuracy of the Genesis account is a factor) and that supposed clashes between them are merely a matter of faulty understanding. Christian theologians and scientists like [[Augustine of Hippo]] and [[Gallileo]] held that, the literality creation in Genesis were believed to be true at the time, it doesn't destroy Christianity to suggest future scientific discoveries might change the way we view this account but, in the same way science could clarify the content of Scripture, it could also stand opposed to it and neither of these men ever proposed that science was superior or more reliable than the Bible.{{Clarifyme|date=March 2008}} This theological understanding is also upheld by the majority of YECs — that science is a very useful tool but still only a tool and that if, by science, something is found to contradict with the Bible, we should first question the science before trying to shift our understanding of the Bible.

Aside from the theological doubts voiced by other Christians, YEC also stands in opposition to the [[creation myth]]ologies of other religions (both [[extant]] and [[extinct]]). Many of these make claims regarding the origin of the universe and humanity that are completely incompatible with those of Christian creationists (and with one another).

== See also ==
{{portal|Creationism}}
{{col-begin}}
{{col-3}}
* [[Antediluvian]]
* [[Biblical cosmology]]
* [[Cosmogony]]
* [[Cosmological argument]]
* [[Creator god]]
* [[Dating Creation]]
* [[Day-Age Creationism]]
* [[Deism]]
* [[Elohim]]

{{col-break}}

* [[Existence]]
* [[Ex nihilo]]
* [[Flat Earth Society]]
* [[Flood Geology]]
* [[Gap Creationism]]
* [[Higher criticism]]
* [[History of Creationism]]
* [[Living dinosaurs]]
* [[Quran]]

{{col-break}}

* [[Rapid-decay theory]]
* [[Rationalism]]
* [[Sons of Noah]]
* [[Starlight problem]]
* [[Theism]]
* [[Timeline of the Universe]]
* [[Ultimate fate of the Universe]]
* [[Ussher chronology]]
* [[Young Earth Creationist cosmologies]]

{{col-end}}
=== Church bodies whose official position is YEC ===
* [[Evangelical Reformed Presbyterian Church]]
* [[Lutheran Church Missouri Synod]]
* [[Protestant Reformed Churches in America]]

== References ==
{{reflist|2}}

== External links ==
===Websites supportive of YEC===
* [http://www.answersingenesis.org Answers in Genesis]
* [http://www.creationontheweb.com/ Creation Ministries International]
* [http://www.icr.org Institute for Creation Research]

=== Websites critical of YEC ===
* [http://www.talkorigins.org/ The TalkOrigins Archive]
* [http://www.noanswersingenesis.org.au/ No Answers In Genesis]
* [http://wiki.cotch.net/index.php/Main_Page EvoWiki]
* [http://www.answersincreation.org Answers In Creation] - Old Earth creationist website purportedly demonstrating the errors of YEC

=== Other ===
* [http://www.religioustolerance.org/ev_publi.htm US poll results — Public beliefs about evolution and creation]
* [http://wiki.cotch.net/index.php/The_History_of_Young_earth_creationism Evowiki article on the History of YEC]

[[Category:Young Earth creationism|*]]
[[Category:Creation science]]

[[ar:نظرية خلق الأرض الفتية]]
[[de:Junge-Erde-Kreationismus]]
[[fr:Créationnisme Jeune-Terre]]
[[ko:젊은 지구 창조론]]
[[nl:Jongeaardecreationisme]]
[[ru:Младоземельный креационизм]]
[[fi:Nuoren Maan kreationismi]]
[[tr:Genç Dünya yaratılışçılığı]]
[[zh:年轻地球创造论]]

Science

2008-10-22T22:38:49Z

ReaganFan0101:

{{sprotect2}}
{{otheruses}}
[[Image:Meissner effect p1390048.jpg|thumb|200px|right|The [[Meissner effect]] causes a [[magnet]] to levitate above a [[high-temperature superconductor]].]]
[[Image:Apollo Moonwalk2.jpg|thumb|right|200px|A human protected by high technology during the first lunar landing, demonstrates knowledge developed through study of the natural sciences.]]
'''Science''' (from the [[Latin]] ''scientia'', meaning "[[knowledge]]" or "knowing") is the effort to [[Discovery (observation)|discover]], and increase human understanding of how the [[physical]] [[world]] works. Through controlled methods, [[scientists]] use [[observable]] [[physical evidence]] of [[natural]] [[phenomena]] to collect data, and analyze this [[information]] to explain what and how things work. Such methods include [[experimentation]] that tries to [[simulate]] natural phenomena under controlled conditions and thought experiments. [[Knowledge]] in science is gained through [[research]].

==Etymology==
[[Image:DNA Overview2.png|thumb|right|upright|[[DNA]] determines the genetic structure of all life on earth]]
The word '''science''' is derived from the [[Latin]] word {{lang|la|''scientia''}} for [[knowledge]], the nominal form of the verb {{lang|la|''scire''}}, "to know". The [[Proto-Indo-European root|Proto-Indo-European]] (PIE) root that yields ''scire'' is ''*skei-'', meaning to "cut, separate, or discern". Other words from the same root include [[Sanskrit]] {{transl|sa|''chyati''}}, "he cuts off", [[Ancient Greek|Greek]] {{transl|grc|''schizo''}}, "I split" (hence English ''schism'', ''schizophrenia''), Latin {{lang|la|''scindo''}}, "I split" (hence English ''rescind'').<ref>[http://www.etymonline.com/index.php?search=science&searchmode=none Etymology of "science" at Etymology Online]. See also details of the PIE root at [http://www.bartleby.com/61/roots/IE464.html American Heritage Dictionary of the English Language'', 4th edition, 2000.].</ref> From the [[Middle Ages]] to the [[Age of Enlightenment|Enlightenment]], ''science'' or ''scientia'' meant any systematic recorded knowledge.<ref>{{cite book | first=Neville | last=MacMorris | year=1989 | title=The Natures of Science | pages=pp. 31–33 | publisher=Fairleigh Dickinson University Press | location=New York | isbn=0838633218 }}</ref> ''Science'' therefore had the same sort of very broad meaning that ''[[philosophy]]'' had at that time. In other languages, including French, Spanish, Portuguese, Italian, Polish and Russian, the word corresponding to ''science'' also carries this meaning.

==History of science==
{{main|History of science}}
While [[empiricism|empirical]] investigations of the natural world have been described since [[Ancient history|antiquity]] (for example, by [[Aristotle]], [[Theophrastus]] and [[Pliny the Elder]]), and [[scientific method]]s have been employed since the [[Middle Ages]] (for example, by [[Ibn al-Haytham]], [[Abū Rayhān al-Bīrūnī]] and [[Roger Bacon]]), the dawn of [[modern science]] is generally traced back to the [[early modern period]], during what is known as the [[Scientific Revolution]] of the [[16th century|16th]] and [[17th century|17th centuries]]. The word ''scientist'' was first coined by [[William Whewell]] in the 19th century. Previously, people investigating nature called themselves [[natural philosophers]].

==History of usage of the word science==
Well into the [[18th century|eighteenth century]], science and natural [[philosophy]] were not quite synonymous, but only became so later with the direct use of what would become known formally as the [[scientific method]], which was earlier developed during the [[Middle Ages]] and [[early modern period]] in Europe and the [[Islamic science|Middle East]] (see [[History of scientific method]]). Prior to the 18th century, however, the preferred term for the study of nature was [[natural philosophy]], while English speakers most typically referred to the study of the human mind as [[moral philosophy]]. By contrast, the word "science" in English was still used in the 17th century to refer to the [[Aristotelianism|Aristotelian]] concept of knowledge which was secure enough to be used as a sure prescription for exactly how to do something. In this differing sense of the two words, the philosopher [[John Locke]] in ''[[An Essay Concerning Human Understanding]]'' wrote that "natural philosophy [the study of nature] is not capable of being made a science".<ref name=Locke1838>{{cite book
| last=Locke | first=J. | authorlink=John Locke | year = 1838
| title = [[An Essay Concerning Human Understanding]]
| publisher = Printed by Thomas Davison }}</ref>

By the early 1800s, natural philosophy had begun to separate from philosophy, though it often retained a very broad meaning. In many cases, ''science'' continued to stand for reliable knowledge about any topic, in the same way it is still used in the broad sense (see the introduction to this article) in modern terms such as [[library science]], [[political science]], and [[computer science]]. In the more narrow sense of ''science'', as natural philosophy became linked to an expanding set of well-defined laws (beginning with Galileo's laws, Kepler's laws, and Newton's laws for motion), it became more popular to refer to natural philosophy as natural science. Over the course of the nineteenth century, moreover, there was an increased tendency to associate science with study of the natural world (that is, the non-human world). This move sometimes left the study of human thought and society (what would come to be called [[social science]]) in a linguistic limbo by the end of the century and into the next.<ref name = Thurs>{{cite book | first=Daniel Patrick | last=Thurs | year=2007 | title=Science Talk: Changing Notions of Science in American Popular Culture| publisher=Rutgers University Press | location=New Brunswick, NJ | isbn = 978-0813540733 | oclc=170031241}}</ref>

Through the 19th century, many English speakers were increasingly differentiating science (meaning a combination of what we now term natural and biological sciences) from all other forms of knowledge in a variety of ways. The now-familiar expression “[[scientific method]],” which refers to the ''prescriptive'' part of how to make discoveries in natural philosophy, was almost unused during the early part of the 19th century, but became widespread after the 1870s, though there was rarely totally agreement about just what it entailed.<ref name = Thurs/> The word "scientist," meant to refer to a systematically-working natural philosopher, (as opposed to an intuitive or empirically-minded one) was coined in 1833 by William Whewell.<ref name=Ross1962>{{cite journal | format = PDF | author = Ross, S. | year = 1962 | title = Scientist: The story of a word | journal = Annals of Science | volume = 18 | issue = 2 | pages = 65–85 | url = http://www.informaworld.com/index/739364907.pdf | accessdate = 2008-02-08 | doi = 10.1080/00033796200202722 }}</ref> Discussion of [[scientist]]s as a special group of people who did science, even if their attributes were up for debate, grew in the last half of the 19th century.<ref name = Thurs/> Whatever people actually meant by these terms at first, they ultimately depicted science, in the narrow sense of the habitual use of the scientific method and the knowledge derived from it, as something deeply distinguished from all other realms of human endeavor.

By the twentieth century, the modern notion of science as a special brand of information about the world, practiced by a distinct group and pursued through a unique method, was essentially in place. It was used to give legitimacy to a variety of fields through such titles as "scientific" medicine, engineering, advertising, or motherhood.<ref name = Thurs/> Over the 1900s, links between science and [[technology]] also grew increasingly strong.

===Distinguished from technology===
By the end of the century, it is arguable that technology had even begun to eclipse science as a term of public attention and praise. Scholarly studies of science have begun to refer to "[[technoscience]]" rather than science or technology separately. Meanwhile, such fields as [[biotechnology]] and [[nanotechnology]] are capturing the headlines. One author has suggested that, in the coming century, "science" may fall out of use, to be replaced by technoscience or even by some more exotic label such as "techknowledgy."<ref name = Thurs/>

==Scientific method==
{{main|Scientific method}}

[[Image:Bohr model.svg|thumb|The [[Bohr model]] of the [[atom]], like many ideas in the [[history of science]], was at first prompted by and later partially disproved by experiment.]]

The [[scientific method]] seeks to explain the events of [[nature]] in a [[reproducible]] way, and to use these reproductions to make useful [[prediction]]s. It is done through observation of natural phenomena, and/or through experimentation that tries to simulate natural events under controlled conditions. It provides an objective process to find solutions to problems in a number of scientific and technological fields.<ref name=backer>{{cite web
| last=Backer | first=Patricia Ryaby
| date=[[October 29]], [[2004]]
| url=http://www.engr.sjsu.edu/pabacker/scientific_method.htm
| title=What is the scientific method?
| publisher=San Jose State University
| accessdate=2008-03-28 }}</ref>

Based on observations of a phenomenon, a scientist may generate a [[Scientific modeling|model]]. This is an attempt to describe or depict the phenomenon in terms of a logical physical or mathematical representation. As empirical evidence is gathered, a scientist can suggest a [[hypothesis]] to explain the phenomenon. This description can be used to make predictions that are testable by experiment or observation using the scientific method. When a hypothesis proves unsatisfactory, it is either modified or discarded.

While performing experiments, [[Scientist]]s may have a preference for one outcome over another, and it is important that this tendency does not bias their interpretation.<ref>{{cite web
| last=van Gelder | first=Tim | year=1999
| url=http://www.philosophy.unimelb.edu.au/tgelder/papers/HeadsIWin.pdf
| format=PDF
| title="Heads I win, tails you lose": A Foray Into the Psychology of Philosophy
| publisher=University of Melbourne
| accessdate=2008-03-28
}}</ref><ref>{{cite web
| last=Pease | first=Craig
| date=[[September 6]], [[2006]]
| url=http://law-and-science.net/Science4BLJ/Scientific_Method/Deliberate.bias/Text.htm
| title=Chapter 23. Deliberate bias: Conflict creates bad science
| work=Science for Business, Law and Journalism
| publisher=Vermont Law School
| accessdate=2008-03-28
}}</ref> A strict following of the scientific method attempts to minimize the influence of a scientist's bias on the outcome of an experiment. This can be achieved by correct [[Design of experiments|experimental design]], and a thorough [[peer review]] of the experimental results as well as conclusions of a study.<ref>{{cite book
| first=David | last=Shatz | year=2004
| title=Peer Review: A Critical Inquiry
| publisher=Rowman & Littlefield | isbn=074251434X
| oclc=54989960
}}</ref><ref>{{cite book
| first=Sheldon | last=Krimsky | year=2003
| title=Science in the Private Interest: Has the Lure of Profits Corrupted the Virtue of Biomedical Research
| publisher=Rowman & Littlefield | isbn=074251479X
| oclc=185926306 }}</ref> Once the experiment results are announced or published, an important cross-check can be the need to validate the results by an independent party.<ref>{{cite book
| first=Ruth Ellen | last=Bulger | year=2002
| coauthors=Heitman, Elizabeth; Reiser, Stanley Joel
| title=The Ethical Dimensions of the Biological and Health Sciences
| edition=2nd edition | isbn=0521008867
| publisher=Cambridge University Press
| oclc=47791316 }}</ref>

Once a hypothesis has survived testing, it may become adopted into the framework of a [[theory (science)|scientific theory]]. This is a logically reasoned, self-consistent model or framework for describing the behavior of certain natural phenomena. A theory typically describes the behavior of much broader sets of phenomena than a hypothesis—commonly, a large number of hypotheses can be logically bound together by a single theory. These broader theories may be formulated using principles such as [[parsimony]] (e.g., "[[Occam's Razor]]"). They are then repeatedly tested by analyzing how the collected evidence ([[fact]]s) compares to the theory. When a theory survives a sufficiently large number of empirical observations, it then becomes a scientific generalization that can be taken as fully verified.

Despite the existence of well-tested theories, science cannot claim absolute knowledge of nature or the behavior of the subject or of the field of study due to [[Epistemology|epistemological]] problems that are unavoidable and preclude the discovery or establishment of absolute [[truth]]. Unlike a mathematical proof, a scientific theory is [[empirical]], and is always open to [[falsifiability|falsification]], if new evidence is presented. Even the most basic and fundamental theories may turn out to be imperfect if new observations are inconsistent with them. Critical to this process is making every relevant aspect of research publicly available, which allows ongoing review and repeating of experiments and observations by multiple researchers operating independently of one another. Only by fulfilling these expectations can it be determined how reliable the experimental results are for potential use by others.

Isaac Newton's Newtonian [[mechanics|law of gravitation]] is a famous example of an established law that was later found not to be universal—it does not hold in experiments involving motion at speeds close to the speed of light or in close proximity of strong gravitational fields. Outside these conditions, Newton's Laws remain an excellent model of motion and gravity. Since general relativity accounts for all the same phenomena that Newton's Laws do and more, general relativity is now regarded as a more comprehensive theory.<ref>{{cite book
| first=Bernard F. | last=Schutz | year=2003
| title=Gravity from the ground up
| publisher=Cambridge University Press
| isbn=0521455065
| oclc=239632969 }}</ref>

=== Mathematics ===
[[Image:Michelsonmorley-boxplot.svg|thumb|Data from the famous [[Michelson–Morley experiment]]]]
[[Mathematics]] is essential to many sciences. One important function of mathematics in science is the role it plays in the expression of scientific ''models''. Observing and collecting measurements, as well as hypothesizing and predicting, often require extensive use of mathematics and mathematical models. [[Calculus]] may be the branch of mathematics most often used in science, but virtually every branch of mathematics has applications in science, including "pure" areas such as [[number theory]] and [[topology]]. Mathematics is fundamental to the understanding of the natural sciences and the social sciences, many of which also rely heavily on [[statistics]].

Statistical methods, comprised of mathematical techniques for summarizing and exploring data, allow scientists to assess the level of reliability and the range of variation in experimental results. Statistical thinking also plays a fundamental role in many areas of science.

[[Computational science]] applies computing power to simulate real-world situations, enabling a better understanding of scientific problems than formal mathematics alone can achieve. According to the [[Society for Industrial and Applied Mathematics]], computation is now as important as theory and experiment in advancing scientific knowledge.<ref>[http://www.siam.org/students/resources/report.php Graduate Education for Computational Science and Engineering], SIAM Working Group on CSE Education. Accessed [[2008-04-27]].</ref>

Whether mathematics itself is properly classified as science has been a matter of some debate. Some thinkers see mathematicians as scientists, regarding physical experiments as inessential or mathematical proofs as equivalent to experiments. Others do not see mathematics as a science, since it does not require an experimental test of its theories and hypotheses. Mathematical [[theorem]]s and [[formula]]s are obtained by [[Mathematical logic|logical]] derivations which presume [[axiom]]atic systems, rather than the combination of [[empirical]] observation and logical reasoning that has come to be known as the [[scientific method]]. In general, mathematics is classified as [[formal science]], while natural and social sciences are classified as [[empirical]] sciences.<ref>{{cite book | title = Philosophy of Science: From Problem to Theory | author = Bunge, Mario Augusto | year = 1998 | publisher = Transaction Publishers | page 24 | isbn = 0-765-80413-1}}</ref>

== Philosophy of science==
[[Image:Bose Einstein condensate.png|right|thumb|Velocity-distribution data of a gas of [[rubidium]] atoms, confirming the discovery of a new phase of matter, the [[Bose–Einstein condensate]].]]
{{main|Philosophy of science}}

The philosophy of science seeks to understand the nature and justification of scientific knowledge. It has proven difficult to provide a definitive [[Scientific method#Philosophical issues|account of the scientific method]] that can decisively serve to distinguish science from non-science. Thus there are legitimate arguments about exactly where the borders are, leading to the [[problem of demarcation]]. There is nonetheless a set of core precepts that have broad consensus among published philosophers of science and within the [[scientific community]] at large.

Science is reasoned-based analysis of [[sensation]] upon our awareness. As such, the scientific method cannot deduce anything about the realm of [[reality]] that is beyond what is observable by existing or theoretical means.<ref>{{cite book
| first=Lawrence A. | last=Kuznar | year=1997
| title=Reclaiming a Scientific Anthropology
| publisher=Rowman Altamira | isbn=076199114X
| oclc=231704464 }}</ref> When a manifestation of our reality previously considered [[supernatural]] is understood in the terms of causes and consequences, it acquires a scientific explanation.<ref>{{cite book
| first=Christopher B. | last=Kaiser | year=2007
| title=Toward a Theology of Scientific Endeavour: The Descent of Science
| publisher=Ashgate Publishing, Ltd. | isbn=0754641597
| oclc=74964819 }}</ref>

Some of the findings of science can be very [[counter-intuitive]]. [[Atomic theory]], for example, implies that a granite boulder which appears a heavy, hard, solid, grey object is actually a combination of subatomic [[Particle physics|particles]] with none of these properties, moving very rapidly in space where the mass is concentrated in a very small fraction of the total volume. Many of humanity's [[folk physics|preconceived notions]] about the workings of the [[universe]] have been challenged by new scientific discoveries. [[Quantum mechanics]], particularly, examines phenomena that seem to defy our most basic postulates about causality and fundamental understanding of the world around us. Science is the branch of knowledge dealing with people and the understanding we have of our environment and how it works.

There are different schools of thought in the philosophy of scientific method. [[Methodological naturalism]] maintains that scientific investigation must adhere to [[empirical]] study and independent verification as a process for properly developing and evaluating natural explanations for [[observation|observable]] phenomena. Methodological naturalism, therefore, rejects [[supernatural]] explanations, [[Appeal to authority|arguments from authority]] and biased [[observational studies]]. [[Critical rationalism]] instead holds that unbiased observation is not possible and a demarcation between natural and supernatural explanations is arbitrary; it instead proposes [[falsifiability]] as the landmark of empirical theories and falsification as the universal empirical method. Critical rationalism argues for the ability of science to increase the scope of testable knowledge, but at the same time against its [[authority]], by emphasizing its inherent [[fallibilism|fallibility]]. It proposes that science should be content with the rational elimination of errors in its theories, not in seeking for their verification (such as claiming [[Certainty|certain]] or probable proof or disproof; both the proposal and falsification of a theory are only of methodological, conjectural, and tentative character in critical rationalism). [[Instrumentalism]] rejects the concept of truth and emphasizes merely the utility of theories as instruments for explaining and predicting phenomena.

==Critiques==
===Science, pseudoscience and nonscience===
{{main|Cargo cult science|Fringe science|Junk science|Pseudoscience|Scientific misconduct}}
Any established body of [[knowledge]] which masquerades as science in an attempt to claim a legitimacy which it would not otherwise be able to achieve on its own terms is not science; it is often known as [[fringe science|fringe]]- or alternative science. The most important of its defects is usually the lack of the carefully controlled and thoughtfully interpreted experiments which provide the foundation of the natural sciences and which contribute to their advancement. Another term, [[junk science]], is often used to describe scientific theories or data which, while perhaps legitimate in themselves, are believed to be mistakenly used to support an opposing position. There is usually an element of political or ideological bias in the use of the term. Thus the arguments in favor of limiting the use of fossil fuels in order to reduce global warming are often characterized as junk science by those who do not wish to see such restrictions imposed, and who claim that other factors may well be the cause of global warming. A wide variety of commercial advertising (ranging from hype to outright fraud) would also fall into this category. Finally, there is just plain bad science, which is commonly used to describe well-intentioned but incorrect, obsolete, incomplete, or over-simplified expositions of scientific ideas.

The status of many bodies of knowledge as true sciences, has been a matter of debate. Discussion and debate abound in this topic with some fields like the [[social sciences|social]] and [[behavioural sciences]] accused by critics of being unscientific. Many groups of people from academicians like Nobel Prize physicist [[Percy W. Bridgman]],<ref>{{cite journal | last = Siepmann | first = J. P. | title=What is Science? (Editorial) | journal=Journal of Theoretics | year=1999 | volume=3 | url=http://adsabs.harvard.edu/abs/1998RPPh...61...77K | accessdate=2007-07-23 }}</ref> or Dick Richardson, Ph.D.—Professor of Integrative Biology at the [[University of Texas at Austin]],<ref>{{cite web | last=Richardson | first=R. H. (Dick) | date=January 28, 2001 | url=http://www.sbs.utexas.edu/resource/onlinetext/Definitions/economicsNOTscience.htm | title=Economics is NOT Natural Science! (It is technology of Social Science.) | publisher=The University of Texas at Austin | accessdate=2007-07-23 }}</ref> to politicians like U.S. Senator [[Kay Bailey Hutchison]] and other co-sponsors,<ref>{{cite web | author=Staff | date=May 19, 2006 | url=http://www.asanet.org/page.ww?section=Advocacy&name=Social+Sciences+Under+Attack | title=Behavioral and Social Science Are Under Attack in the Senate | publisher=American Sociological Association | accessdate=2007-07-23 }}</ref> oppose giving their support or agreeing with the use of the label "science" in some fields of study and knowledge they consider non-scientific, ambiguous, or scientifically irrelevant compared with other fields. [[Karl Popper]] denied the existence of evidence<ref>''Logik der Forschung'', new appendix ''*XIX'' (not yet available in the English edition ''Logic of scientific discovery'')</ref> and of scientific method.<ref>{{cite book
| first=Karl | last=Popper | authorlink=Karl Popper
| chapter=Preface, On the non-existence of scientific method
| title=Realism and the Aim of Science
| year=1983 | edition=1st edition
| publisher=Rowman and Littlefield
| location=Totowa, New Jersey }}</ref> Popper holds that there is only one universal method, the negative method of [[trial and error]]. It covers not only all products of the human mind, including science, mathematics, philosophy, art and so on, but also the evolution of life.<ref>Karl Popper: ''Objective Knowledge'' (1972)</ref> He also contributed to the [[Positivism dispute]], a philosophical dispute between [[Critical rationalism]] ([[Popper]],[[Albert]]) and the [[Frankfurt School]] ([[Adorno]], [[Habermas]]) about the methodology of the social sciences.<ref>Critical examination of various positions on this issue can be found in [[Karl R. Popper]]'s ''The Poverty of Historicism''.</ref>

===Philosophical focus===
Historian [[Jacques Barzun]] termed science "a [[faith]] as [[fanaticism|fanatical]] as any in [[history]]" and warned against the use of scientific thought to suppress considerations of [[meaning]] as integral to [[humanity|human]] existence.<ref>Jacques Barzun, ''Science: The Glorious Entertainment'', Harper and Row: 1964. p. 15. (quote) and Chapters II and XII.</ref> Many recent thinkers, such as [[Carolyn Merchant]], [[Theodor Adorno]] and [[E. F. Schumacher]] considered that the 17th century [[scientific revolution]] shifted science from a focus on understanding [[nature]], or [[wisdom]], to a focus on manipulating nature, i.e. [[power (sociology)|power]], and that science's emphasis on manipulating nature leads it inevitably to manipulate people, as well.<ref name=UW>Fritjof Capra, ''Uncommon Wisdom'', ISBN 0-671-47322-0, p. 213</ref> Science's focus on quantitative measures has led to critiques that it is unable to recognize important qualitative aspects of the world.<ref name=UW/> It is not clear, however, if this kind of criticism is adequate to a vast number of non-experimental scientifics fields like [[Astronomy]], [[Cosmology]], [[Evolutionary Biology]], [[Complexity Theory]], [[Paleontology]], [[Paleoanthropology]], [[Archeology]], [[Earth Sciences]], [[Climatology]], [[Ecology]] and other sciences, like [[Statistical Physics]] of irreversible [[non-linear]] systems, that emphasize systemic and historically contingent frozen accidents. Considerations about the philosophical impact of science to the discussion of the (or lack of) meaning in human existence are not supressed but strongly discussed in the literature of science divulgation, a movement sometimes called [[The Third Culture]].

The implications of the ideological denial of [[ethics]] for the practice of science itself in terms of fraud, plagiarism, and data falsification, has been criticized by several academics. In "Science and Ethics", the philosopher [[Bernard Rollin]] examines the ideology that denies the relevance of ethics to science, and argues in favor of making education in ethics part and parcel of scientific training.<ref>{{cite book
| first=Bernard E. | last=Rollin | year=2006
| title=Science and Ethics
| publisher=Cambridge University Press
| isbn=0521857546
| oclc=238793190 }}</ref>

===The media and the scientific debate===
The [[mass media]] face a number of pressures that can prevent them from accurately depicting competing scientific claims in terms of their credibility within the scientific community as a whole. Determining how much weight to give different sides in a scientific debate requires considerable expertise on the issue at hand.<ref>{{cite web
| last=Dickson | first=David | date=[[October 11]], [[2004]]
| url=http://www.scidev.net/Editorials/index.cfm?fuseaction=readEditorials&itemid=131&language=1
| title=Science journalism must keep a critical edge
| publisher=Science and Development Network
| accessdate=2008-02-20
}}</ref> Few journalists have real scientific knowledge, and even beat reporters who know a great deal about certain scientific issues may know little about other ones they are suddenly asked to cover.<ref>{{cite web
| last=Mooney | first=Chris | year=2007
| url=http://cjrarchives.org/issues/2004/6/mooney-science.asp
| title=Blinded By Science, How 'Balanced' Coverage Lets the Scientific Fringe Hijack Reality
| publisher=Columbia Journalism Review
| accessdate=2008-02-20
}}</ref><ref>{{cite journal
| last=McIlwaine | first=S. | coauthors=Nguyen, D. A.
| title=Are Journalism Students Equipped to Write About Science?
| journal=Australian Studies in Journalism
| year=2005 | volume=14 | pages=41–60
| url=http://espace.library.uq.edu.au/view/UQ:8064
| accessdate=2008-02-20 }}</ref>

===Epistemological inadequacies===
Psychologist [[Carl Jung]] believed that though science attempted to understand all of nature, the experimental method used would pose artificial, conditional questions that evoke only partial answers.<ref>{{cite book | isbn = 0691017948 | title = Synchronicity: An Acausal Connecting Principle | pages = 35 | publisher = Princeton University Press | last = Jung | first = Carl | year = 1973 | authorlink = Carl Jung}}</ref> [[Robert Anton Wilson]] criticized science for using instruments to ask questions that produce answers only meaningful in terms of the instrument, and that there was no such thing as a completely objective vantage point from which to view the results of science.<ref>{{cite video|
| people=Wilson, Robert Anton
| title=[http://www.youtube.com/watch?v=lO7tGOr2NU0 Real Reality]
| medium=Adobe Flash video | publisher=YouTube
| year2=[[2007]] }}</ref>

== Scientific community ==
{{main|Scientific community}}
The scientific community consists of the total body of scientists, its relationships and interactions. It is normally divided into "sub-communities" each working on a particular field within science.

=== Fields ===
{{main|Fields of science}}

Fields of science are commonly classified along two major lines: [[natural science]]s, which study [[natural]] phenomena (including [[Biology|biological life]]), and [[social sciences]], which study [[human behavior]] and [[Society|societies]]. These groupings are [[empirical]] sciences, which means the knowledge must be based on [[Observation|observable]] [[phenomena]] and capable of being [[experiment]]ed for its [[validity]] by other researchers working under the same conditions.<ref name=Popper>{{cite book | last = Popper | first = Karl | authorlink = Karl Popper | title = The Logic of Scientific Discovery | origyear = 1959 | edition = 2nd English edition | year = 2002 | publisher = Routledge Classics | location = New York, NY | isbn = 0-415-27844-9 | oclc =59377149 }}</ref> There are also related disciplines that are grouped into interdisciplinary and applied sciences, such as [[engineering]] and [[health science]]. Within these categories are specialized scientific fields that can include elements of other scientific disciplines but often possess their own terminology and body of expertise.<ref>See: {{cite web | author=Editorial Staff | date=March 7, 2007 | url=http://www.seedmagazine.com/news/2007/03/scientific_method_relationship.php | title=Scientific Method: Relationships among Scientific Paradigms | publisher=Seed magazine | accessdate=2007-09-12 }}</ref>

[[Mathematics]], which is sometimes classified within a third group of science called [[formal science]], has both similarities and differences with the natural and social sciences.<ref name=Popper/> It is similar to [[empirical]] sciences in that it involves an objective, careful and systematic study of an area of knowledge; it is different because of its method of verifying its knowledge, using [[A priori and a posteriori (philosophy)|''a priori'']] rather than empirical methods.<ref name=Popper/> [[Formal science]], which also includes [[statistics]] and [[logic]], is vital to the empirical sciences. Major advances in formal science have often led to major advances in the physical and biological sciences. The formal sciences are essential in the formation of [[hypotheses]], [[theories]], and [[physical law|laws]],<ref name=Popper/> both in discovering and describing how things work (natural sciences) and how people think and act (social sciences).

=== Institutions ===
[[Image:Académie des Sciences 1671.jpg|thumb|150px|[[Louis XIV]] visiting the {{lang|fr|[[French Academy of Sciences|Académie des sciences]]}} in 1671.]]

[[Learned society|Learned societies]] for the communication and promotion of scientific thought and experimentation have existed since the [[Renaissance]] period.<ref>{{cite web | last=Parrott | first=Jim | date=August 9, 2007 | url=http://www.scholarly-societies.org/1599andearlier.html | title=Chronicle for Societies Founded from 1323 to 1599 | publisher=Scholarly Societies Project | accessdate=2007-09-11}}</ref> The oldest surviving institution is the {{lang|it|''[[Accademia dei Lincei]]''}} in [[Italy]].<ref>{{cite web | year=2006 | url=http://positivamente.lincei.it/ | title=Benvenuto nel sito dell'Accademia Nazionale dei Lincei | language=Italian | publisher=Accademia Nazionale dei Lincei | accessdate=2007-09-11}}</ref> National [[Academy of Sciences]] are distinguished institutions that exist in a number of countries, beginning with the British ''[[Royal Society]]'' in 1660<ref>{{cite web | url=http://www.royalsoc.ac.uk/page.asp?id=2176 | title=Brief history of the Society | publisher=The Royal Society | accessdate=2007-09-11}}</ref> and the French {{lang|fr|''[[Académie des Sciences]]''}} in 1666.<ref>{{cite web | first=G.G. | last=Meynell | url=http://www.royalsoc.ac.uk/page.asp?id=2176 | title=The French Academy of Sciences, 1666-91: A reassessment of the French Académie royale des sciences under Colbert (1666-83) and Louvois (1683-91) | publisher=Topics in Scientific & Medical History | accessdate=2007-09-11}}</ref>

International scientific organizations, such as the ''[[International Council for Science]]'', have since been formed to promote cooperation between the scientific communities of different nations. More recently, influential government agencies have been created to support scientific research, including the ''[[National Science Foundation]]'' in the [[United States|U.S.]]

Other prominent organizations include the [[academy of Sciences|academies of science]] of many nations, [[CSIRO]] in Australia, {{lang|fr|[[Centre national de la recherche scientifique]]}} in France, [[Max Planck Society]] and {{lang|de|[[Deutsche Forschungsgemeinschaft]]}} in Germany, and in Spain, [[CSIC]].

=== Literature ===
{{main|Scientific literature}}

An enormous range of [[scientific literature]] is published.<ref>{{cite journal
| last=Ziman | first=Bhadriraju
| journal=Science
| title=The proliferation of scientific literature: a natural process
| year=1980 | volume=208 | issue=4442
| pages=369–371
| doi= 10.1126/science.7367863
| pmid=7367863 }}</ref> [[Scientific journal]]s communicate and document the results of research carried out in universities and various other research institutions, serving as an archival record of science. The first scientific journals, ''[[Journal des Sçavans]]'' followed by the ''[[Philosophical Transactions of the Royal Society|Philosophical Transactions]]'', began publication in 1665. Since that time the total number of active periodicals has steadily increased. As of 1981, one estimate for the number of scientific and technical journals in publication was 11,500.<ref>{{cite book
| first=Krishna | last=Subramanyam
| coauthors=Subramanyam, Bhadriraju | year=1981
| title=Scientific and Technical Information Resources
| publisher=CRC Press | isbn=0824782976
| oclc=232950234 }}</ref> While [[Pubmed]] lists almost 40,000, related to the medical sciences only.<ref> ftp://ftp.ncbi.nih.gov/pubmed/J_Entrez.txt</ref>

Most scientific journals cover a single scientific field and publish the research within that field; the research is normally expressed in the form of a [[scientific paper]]. Science has become so pervasive in modern societies that it is generally considered necessary to communicate the achievements, news, and ambitions of scientists to a wider populace.

[[Science magazine]]s such as [[NewScientist|New Scientist]], [[Science & Vie]] and [[Scientific American]] cater to the needs of a much wider readership and provide a non-technical summary of popular areas of research, including notable discoveries and advances in certain fields of research. [[Science book]]s engage the interest of many more people. Tangentially, the [[science fiction]] genre, primarily fantastic in nature, engages the public imagination and transmits the ideas, if not the methods, of science.

Recent efforts to intensify or develop links between science and non-scientific disciplines such as [[Literature]] or, more specifically, [[Poetry]], include the ''Creative Writing <-> Science'' resource developed through the [[Royal Literary Fund]].<ref>{{cite web
| first=Mario | last=Petrucci
| url=http://writeideas.org.uk/creativescience/index.htm
| title=Creative Writing <-> Science
| accessdate=2008-04-27 }}</ref>

== See also ==
{{Portal|Science|Nuvola apps kalzium.png}}
: ''Main lists: [[List of basic science topics]] and [[List of science topics]]''
{| class="wikitable" style="float:left; margin-left:.5em; font-size:90%;"
!Application
|
* [[Military funding of science]]
* [[Scientific computing]]
* [[Scientific enterprise]]
* [[Science and technology]]
|-
!Controversy
|
* [[Fringe science]]
* [[Junk science]]
* [[Pathological science]]
* [[Pseudoscience]]
* [[Relationship between religion and science]]
* [[Creation-evolution controversy]]
* [[Scientific misconduct]]
* [[Scientific skepticism]]
|-
!History
|
* [[History of science and technology]]
* [[Historiography of science]]
* [[Protoscience]]
* [[Scientific constants named after people]]
* [[Scientific laws named after people]]
* [[Scientific phenomena named after people]]
* [[Scientific revolution]]
* [[Scientific units named after people]]
* [[Scientometry]]
|-
!Philosophy
|
* [[Naturalism (philosophy)]]
* [[Philosophy of science]]
* [[Rhetoric of science]]
* [[Scientific method]]
* [[Antiscience]]
|-
!Media
|
* [[List of publications in science]]
* [[Science.tv]]
|}
{{-}}

==Notes==
{{reflist}}

==References==
* [[Paul Feyerabend|Feyerabend, Paul]] (2005). ''Science, history of the philosophy'', as cited in {{cite book |author=Honderich, Ted |title=The Oxford companion to philosophy |publisher=Oxford University Press |location=Oxford [[Oxfordshire]] |year=2005 |pages= |isbn=0199264791 |oclc= 173262485|doi=}} of.'' Oxford Companion to Philosophy. Oxford.
*[[David Papineau|Papineau, David]]. (2005). ''Science, problems of the philosophy of.'', as cited in {{cite book |author=Honderich, Ted |title=The Oxford companion to philosophy |publisher=Oxford University Press |location=Oxford [[Oxfordshire]] |year=2005 |pages= |isbn=0199264791 |oclc= 173262485|doi=}}
*{{cite book | author = Feynman, R.P. | year = 1999 | title = The Pleasure of Finding Things Out: The Best Short Works of Richard P. Feynman | publisher = Perseus Books Group | isbn = 0465023959 | oclc = 181597764 }}

==Further reading==
* Augros, Robert M., Stanciu, George N., "The New Story of Science: mind and the universe", Lake Bluff, Ill.: Regnery Gateway, c1984. ISBN 0895268337
* [http://lipas.uwasa.fi/~ts/popsci.html A Book List of Popularized Natural and Behavioral Sciences]
* Baxter, Charles {{PDFlink|[http://www.adihome.org/phpshop/pdf/articles/DIN_02_01_10.pdf "Myth versus science in educational systems"]|66.4 KB}}
*{{cite book|last=Becker|first=Ernest|title=The structure of evil; an essay on the unification of the science of man|location=New York|publisher=G. Braziller|year=1968|authorlink=Ernest Becker}}
* "''[http://etext.lib.virginia.edu/cgi-local/DHI/dhi.cgi?id=dv1-57 Classification of the Sciences]''". Dictionary of the History of Ideas.
* Cole, K. C., ''Things your teacher never told you about science: Nine shocking revelations'' [[Newsday]], [[Long Island, New York]], March 23, 1986, pg 21+
* Feynman, Richard [http://calteches.library.caltech.edu/51/02/CargoCult.pdf "Cargo Cult Science"]
* Gopnik, Alison, [http://www.amacad.org/publications/winter2004/gopnik.pdf "Finding Our Inner Scientist"], [[Daedalus (journal)|Daedalus]], Winter 2004.
* Krige, John, and Dominique Pestre, eds., ''Science in the Twentieth Century'', Routledge 2003, ISBN 0-415-28606-9
* [[Thomas Samuel Kuhn|Kuhn, Thomas]], ''[[The Structure of Scientific Revolutions]]'', 1962.
* MacComas, William F. {{PDFlink|[http://earthweb.ess.washington.edu/roe/Knowability_590/Week2/Myths%20of%20Science.pdf "The principal elements of the nature of science: Dispelling the myths"]|189 KB}} Rossier School of Education, University of Southern California. Direct Instruction News. '''Spring 2002''' 24–30.
* [http://evolution.berkeley.edu/evosite/nature/index.shtml "Nature of Science"] University of California Museum of Paleontology
* {{cite book| last = Obler | first = Paul C. | coauthors = Estrin, Herman A. | title = The New Scientist: Essays on the Methods and Values of Modern Science | publisher = Anchor Books, Doubleday | date = 1962}}
* {{cite book | first=Daniel Patrick | last=Thurs | year=2007 | title=Science Talk: Changing Notions of Science in American Popular Culture| pages=pp. 22–52 | publisher=Rutgers University Press | location=New Brunswick, NJ | isbn=978-0-8135-4073-3 }}

==External links==
{{sisterlinks|Science}}
'''Publications''':
* "''[[b:GCSE Science|GCSE Science textbook]]''". [[Wikibooks]].org

'''News''':
* [http://www.newscientist.com Current Events]. [[New Scientist]] Magazine, Reed Business Information, Ltd.
* [http://www.sciencedaily.com ScienceDaily]
* [http://www.discovermagazine.com Discover Magazine]

'''Resources''':
* [http://www.science.gov United States Science Initiative]. Selected science information provided by U.S. Government agencies, including research and development results.
* [http://www.euroscience.org/ Euroscience]:
** [http://www.euroscience.org/esof.html Euroscience Open Forum] (ESOF)
[[Category:Science|Science]]
* [http://www.scienceresourceonline.com Science Resources]

{{Link FA|nl}}
{{Link FA|tr}}
[[af:Wetenskap]]
[[ar:علم]]
[[an:Zenzia]]
[[as:বিজ্ঞান]]
[[ast:Ciencia]]
[[ay:Yatxatawi]]
[[az:Elm]]
[[bn:বিজ্ঞান]]
[[zh-min-nan:Kho-ha̍k]]
[[ba:Фән]]
[[be:Навука]]
[[be-x-old:Навука]]
[[bar:Wissnschåft]]
[[bs:Nauka]]
[[br:Skiant]]
[[bg:Наука]]
[[ca:Ciència]]
[[cv:Ăслăлăх]]
[[ceb:Siyensiya]]
[[cs:Věda]]
[[cy:Gwyddoniaeth]]
[[da:Videnskab]]
[[de:Wissenschaft]]
[[et:Teadus]]
[[el:Επιστήμη]]
[[es:Ciencia]]
[[eo:Scienco]]
[[eu:Zientzia]]
[[fa:علم]]
[[fr:Science]]
[[fur:Sience]]
[[ga:Eolaíocht]]
[[gd:Saidheans]]
[[gl:Ciencia]]
[[gan:科學]]
[[gu:વિજ્ઞાન]]
[[zh-classical:格致]]
[[hak:Khô-ho̍k]]
[[ko:과학]]
[[hi:विज्ञान]]
[[hr:Znanost]]
[[io:Cienco]]
[[bpy:বিজ্ঞান]]
[[id:Ilmu]]
[[ia:Scientia]]
[[is:Vísindi]]
[[it:Scienza]]
[[he:מדע]]
[[jv:Èlmu]]
[[kn:ವಿಜ್ಞಾನ]]
[[ka:მეცნიერება]]
[[csb:Ùczba]]
[[kk:Ғылым]]
[[kw:Godhonieth]]
[[sw:Sayansi]]
[[kg:Kizabu]]
[[ht:Syans]]
[[ku:Zanist]]
[[la:Scientia]]
[[lv:Zinātne]]
[[lb:Wëssenschaft]]
[[lt:Mokslas]]
[[li:Weitesjap]]
[[jbo:saske]]
[[hu:Tudomány]]
[[mk:Наука]]
[[ml:ശാസ്ത്രം]]
[[mt:Xjenza]]
[[ms:Sains]]
[[mn:Шинжлэх ухаан]]
[[nah:Tlamatiliztli]]
[[nl:Wetenschap]]
[[ne:विज्ञान]]
[[ja:科学]]
[[pih:Saiens]]
[[no:Vitenskap]]
[[nn:Vitskap]]
[[nrm:Scienche]]
[[uz:Fan]]
[[pap:Siensia]]
[[pms:Siensa]]
[[nds:Wetenschop]]
[[pl:Nauka]]
[[pt:Ciência]]
[[crh:İlim]]
[[ro:Ştiinţă]]
[[ru:Наука]]
[[sm:Saienisi]]
[[sco:Science]]
[[sq:Shkenctari]]
[[scn:Scienza]]
[[simple:Science]]
[[ss:Isayensi]]
[[sk:Veda]]
[[sl:Znanost]]
[[sr:Наука]]
[[sh:Nauka]]
[[su:Élmu]]
[[fi:Tiede]]
[[sv:Naturvetenskap]]
[[tl:Agham]]
[[ta:அறிவியல்]]
[[th:วิทยาศาสตร์]]
[[vi:Khoa học]]
[[tr:Bilim]]
[[uk:Наука]]
[[ur:سائنس]]
[[vec:Sienzsa]]
[[wa:Syince]]
[[yi:וויסנשאפט]]
[[yo:Sáyẹ́nsì]]
[[zh-yue:科學]]
[[bat-smg:Muokslos]]
[[zh:科学]]