09 February 2007

Statistical Ignoramuses Overload Climate Science

In modern scientific studies, it is important that competent statisticians have input into the data analysis phase. In climate science, many researchers seem to have forgotten that basic step. As a result, much of what most journalists and members of the public believe has been "proven" about climate change, is simply wrong.
Dr. Wegman is a professor at the Center for Computational Statistics at George Mason University, chair of the National Academy of Sciences' Committee on Applied and Theoretical Statistics, and board member of the American Statistical Association. Few statisticians in the world have CVs to rival his (excerpts appear nearby).

Wegman became involved in the global-warming debate after the energy and commerce committee of the U.S. House of Representatives asked him to assess one of the hottest debates in the global-warming controversy: the statistical validity of work by Michael Mann. You may not have heard of Mann or read Mann's study but you have often heard its famous conclusion: that the temperature increases that we have been experiencing are "likely to have been the largest of any century during the past 1,000 years" and that the "1990s was the warmest decade and 1998 the warmest year" of the millennium. You may have also heard of Mann's hockey-stick shaped graph, which showed relatively stable temperatures over most of the last millennium (the hockey stick's long handle), followed by a sharp increase (the hockey stick's blade) this century.

Mann's findings were arguably the single most influential study in swaying the public debate, and in 2001 they became the official view of the International Panel for Climate Change, the UN body that is organizing the worldwide effort to combat global warming. But Mann's work also had its critics, particularly two Canadians, Steve McIntyre and Ross McKitrick, who published peer-reviewed critiques of their own.

Wegman accepted the energy and commerce committee's assignment, and agreed to assess the Mann controversy pro bono. He conducted his third-party review by assembling an expert panel of statisticians, who also agreed to work pro bono. Wegman also consulted outside statisticians, including the Board of the American Statistical Association. At its conclusion, the Wegman review entirely vindicated the Canadian critics and repudiated Mann's work.

You may remember that "hockey stick" graph from Al Gore's unintentionally comedic documentary, "An Inconvenient Truth." Dr. Wegman apparently confirmed the McIntyre and McKitrick paper that revealed Mann's hockey stick as garbage science. Al Gore was a bit slow on the uptake, and even the IPCC still releases statements based upon the phony hockey stick claims.

Here are links to a series from the National Post on science skeptics of the orthodox doctrine of CAGW--catastrophic anthropogenic global warming. It's really more fun to be a skeptic--especially when the orthodoxy is as dimwitted as this one seems to be.

The entire series is well worth reading:

Statistics needed -- The Deniers Part I

Warming is real -- and has benefits -- The Deniers Part II

The hurricane expert who stood up to UN junk science -- The Deniers Part III

Polar scientists on thin ice -- The Deniers Part IV

The original denier: into the cold -- The Deniers Part V

The sun moves climate change -- The Deniers Part VI

Will the sun cool us? -- The Deniers Part VII

The limits of predictability -- The Deniers Part VIII

Look to Mars for the truth on global warming -- The Deniers Part IX

Limited role for C02 -- the Deniers Part X

Dr. Shariv's digging led him to the surprising discovery that there is no concrete evidence -- only speculation -- that man-made greenhouse gases cause global warming. Even research from the Intergovernmental Panel on Climate Change-- the United Nations agency that heads the worldwide effort to combat global warming -- is bereft of anything here inspiring confidence. In fact, according to the IPCC's own findings, man's role is so uncertain that there is a strong possibility that we have been cooling, not warming, the Earth. Unfortunately, our tools are too crude to reveal what man's effect has been in the past, let alone predict how much warming or cooling we might cause in the future.

All we have on which to pin the blame on greenhouse gases, says Dr. Shaviv, is "incriminating circumstantial evidence," which explains why climate scientists speak in terms of finding "evidence of fingerprints." Circumstantial evidence might be a fine basis on which to justify reducing greenhouse gases, he adds, "without other 'suspects.' " However, Dr. Shaviv not only believes there are credible "other suspects," he believes that at least one provides a superior explanation for the 20th century's warming.

"Solar activity can explain a large part of the 20th-century global warming," he states, particularly because of the evidence that has been accumulating over the past decade of the strong relationship that cosmic- ray flux has on our atmosphere. So much evidence has by now been amassed, in fact, that "it is unlikely that [the solar climate link] does not exist."

The sun's strong role indicates that greenhouse gases can't have much of an influence on the climate -- that C02 et al. don't dominate through some kind of leveraging effect that makes them especially potent drivers of climate change. The upshot of the Earth not being unduly sensitive to greenhouse gases is that neither increases nor cutbacks in future C02 emissions will matter much in terms of the climate.

Even doubling the amount of CO2 by 2100, for example, "will not dramatically increase the global temperature," Dr. Shaviv states. Put another way: "Even if we halved the CO2 output, and the CO2 increase by 2100 would be, say, a 50% increase relative to today instead of a doubled amount, the expected reduction in the rise of global temperature would be less than 0.5C. This is not significant."

Hat tip Climate Audit Blog.

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“During times of universal deceit, telling the truth becomes a revolutionary act” _George Orwell

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