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'''YAD06''' is a tree growing in the Yamal Peninsula of Siberia. A core sample from this tree, YADO61, provided data used to support Michael Mann's [[hockey stick]] interpretation of global climate history. Mann's graph was first published in 1998. It shows global temperatures as stable for 900 years until the 20th century, when carbon dioxide emissions supposedly caused a rapid increase in global temperature. Mann create the graph to address reconstructions made by earlier climatologists that show a [[Medieval Warm Period]] between 950 and 1150. These reconstructions show that the climate was somewhat warmer at that time than it is at present. Although Mann claimed to have used a dozen proxies, analysis showed that only the data from YAD06 had the hockey stick pattern that Mann reported as his result.<ref>A comparison of the various tree cores from Yamal can be seen [http://wattsupwiththat.com/2009/10/01/response-from-briffa-on-the-yamal-tree-ring-affair-plus-rebuttal/ here].</ref>

'''YAD06''' is a tree growing in the Yamal Peninsula of Siberia. A core sample from this tree, YADO61, provided data used to support Michael Mann's [[hockey stick]] interpretation of global climate history. Mann's graph was first published in 1998. It shows global temperatures as stable for 900 years until the 20th century, when carbon dioxide emissions supposedly caused a rapid increase in global temperature. Mann create the graph to address reconstructions made by earlier climatologists that show a [[Medieval Warm Period]] between 950 and 1150. These reconstructions show that the climate was somewhat warmer at that time than it is at present. Although Mann claimed to have used a dozen proxies, analysis showed that only the data from YAD06 had the hockey stick pattern that Mann reported as his result. Compared to other samples taken Yamal, the YAD061 core was an outliner by a factor of 8 sigma.<ref>Watts, Anthony,"[http://wattsupwiththat.com/2009/10/01/response-from-briffa-on-the-yamal-tree-ring-affair-plus-rebuttal/ Response from Briffa on the Yamal tree ring affair – plus rebuttal]," October 1, 2009.</ref>

Mann's graph appeared prominently in the report of the UN's Intergovernmental Panel on Climate Change, used a basis for international policy on climate change. YAD06 has been dubbed, "the most influential tree in the world." Even the cherry-picked YAD06 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 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.<ref>Booker, Christopher, "[http://www.telegraph.co.uk/comment/columnists/christopherbooker/6738111/Climategate-reveals-the-most-influential-tree-in-the-world.html Climategate reveals 'the most influential tree in the world']", ''The Telegraph'', Dec. 5, 2009.</ref>

Mann's graph appeared prominently in the report of the UN's Intergovernmental Panel on Climate Change, used a basis for international policy on climate change. YAD06 has been dubbed, "the most influential tree in the world." Even the cherry-picked YAD06 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 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.<ref>Booker, Christopher, "[http://www.telegraph.co.uk/comment/columnists/christopherbooker/6738111/Climategate-reveals-the-most-influential-tree-in-the-world.html Climategate reveals 'the most influential tree in the world']", ''The Telegraph'', Dec. 5, 2009.</ref>