10 December 2009

Stephen H. Schneider: Hammering Out a Deal for Our Future #cop15 #climate

Hockey Stick vs. Fingerprinting

Unfortunately, Climate Denier Gate is being used by some on blogs and the usual suspects in media to lionize the perpetrators as some kind of heroic stealth investigative reporters who have just in time saved the world from the “big mistake” of fashioning climate policy in Copenhagen. The amazing scientific thing that nobody seems to be covering is that the "hockey stick" was never used as proof of anthropogenic global warming by IPCC—it was the "fingerprinting" studies of many scientists dating back to 1995—three years before the first hockey stick was even published. A fingerprint is an attempt to combine models of climate change with observed data. The models are driven by natural forces like solar variations or volcanic eruptions, and their retrodictions of what should have happened between 1900 and 2000 are compared to what actually happened. Then the models are driven by anthropogenic forces such as increasing greenhouse gases as has been observed and again compared to what actually happened to the 20th century climate. And finally models are driven by combined natural and anthropogenic forces—and as expected, the latter has the highest correlation with observations, the former the least and the middle one in between correlations. That is a smoking gun—but for AGW—and the number of such studies appearing in the peer reviewed scientific literature since 1995 has multiplied. Ergo, IPCC has increased its confidence in AGW over successive studies, with the “very likely” the most recent 2007 assessment.

For those who, because of lack of time or attention span, aren't getting to the bottom of this article.

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