Anthropogenic global warming is any increase in global average air temperature caused by human activities.
An assessment panel created by the United Nations is 90% sure that most global warming is caused by human beings.
The idea that human activities, such as the combustion of fossil fuels, can significantly warm the earth's atmosphere is sometimes referred to as the enhanced greenhouse effect.
Relation to current climate change
The anthropogenic global warming theory is one of several explanations for the approximately 1.2 degrees F warming of the earth's surface recorded since the beginning of the 20th century.
The theory enjoys broad based political support from Liberals, Greens and the US Democratic Party, and theory supporters frequently assert the existence of a "scientific consensus" favoring their viewpoint (see Politics of global warming).
Assessment of the theories
President Bush's primary science advisor, Dr. John H. Marburger, supports anthropogenic global warming.[1] A number of key Republicans support taking action to combat global warming as well, including George W. Bush. [2]