Wednesday, December 02, 2009

The Hockey Stick Graph Is Still True In Spite of Climategate

The "Hockey Stick" graph was the result of the first comprehensive attempt to reconstruct the average northern hemisphere temperature over the past 1000 years, based on numerous indicators of past temperatures, such as tree rings. The graph is relatively flat from the period A.D. 1000 to 1900, indicating that temperatures were relatively stable for this period of time. The flat part forms the stick's "shaft." After 1900, however, temperatures appear to shoot up, forming the hockey stick's "blade"(see graphic, right). The hockey graph was first published in a 1999 paper (pdf) by Michael Mann and colleagues.

It provided yet more evidence that the rise in greenhouse gases due human activity is causing warming, although the case for this was already very strong. The conclusion that we are making the world warmer certainly does not depend on reconstructions of temperature prior to direct records.

The hockey graph/paper was an extension of a 1998 study in Nature. The graph was highlighted in the 2001 report of the Intergovernmental Panel on Climate Change (IPCC). The Hockey Stick Graph is not under attack due to the Climategate email scandal. The Center maintains that although there is controversy surrounding the Hockey Stick now due to Dr. Mann's email statements, data presented by the National Oceanic and Atmospheric Administration (NOAA) clearly verifies its findings. (Newscientist)

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