Yamal 06

Yamal 06 is a tree in Yamal, Siberia. Its rings provided data used to support Michael Mann's hockey stick interpretation of global climate history. According to Mann's theory, global temperatures had been stable for centuries until carbon dioxide emissions caused them to increase in the 20th century. Other climatologists have suggested there was a Medieval Warm Period between 950 and 1150 during which global temperatures were somewhat warmer than they are at present. Although Mann claimed to have used numerous proxies, analysis showed that only the data from Yamal 06 had the hockey stick pattern that Mann reported as his result. Mann graph appeared prominently in the report of the UN's Intergovernmental Panel on Climate Change, used a basis for international policy on climate change. Yamal 06 has been dubbed, "the most influential tree in the world." Even the cherry-picked Yamal 06 data did not correspond closely enough to a hockey stick pattern to serve Mann's purpose. It shows a temperature decline since 1960, which is wildly unrepresentative of the pattern of global temperature as a whole. This inconvenient trend was disguised with further manipulation. For the post-1960 period, "Mike [Mann]'s Nature trick of adding in the real temps" was used to "hide the decline," according to the Climategate emails.