The 97 Percent ‘Statistic’ — Is There Nothing It Can’t Do?

The 97 Percent ‘Statistic’ — Is There Nothing It Can’t Do?

This video clip of Ted Cruz disemboweling Aaron Mair, the head of the Sierra Club, is making the rounds. It shows Cruz at his very best, cross-examining a witness to a pulp. The most striking thing, however, is how unbelievably hackish and ill-prepared Mair is. Here’s the video:

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Over and over again, Mair simply says that he’s going to rely on the 97 percent of scientists who say that global warming is happening, it’s caused by man and it’s a huge problem. People of good faith can take Mair’s position on one or all of those particulars. But the 97 percent stat is pure public relations b.s. 

Here’s a good explainer by Joseph Bast and Roy Spencer on where that number — which Barack Obama, John Kerry and countless other politicians and journalists retail uncritically:

One frequently cited source for the consensus is a 2004 opinion essay published in Science magazine by Naomi Oreskes, a science historian now at Harvard. She claimed to have examined abstracts of 928 articles published in scientific journals between 1993 and 2003, and found that 75% supported the view that human activities are responsible for most of the observed warming over the previous 50 years while none directly dissented.

Ms. Oreskes’s definition of consensus covered “man-made” but left out “dangerous”—and scores of articles by prominent scientists such as Richard Lindzen, John Christy,Sherwood Idso and Patrick Michaels, who question the consensus, were excluded. The methodology is also flawed. A study published earlier this year in Nature noted that abstracts of academic papers often contain claims that aren’t substantiated in the papers.

Another widely cited source for the consensus view is a 2009 article in “Eos, Transactions American Geophysical Union” by Maggie Kendall Zimmerman, a student at the University of Illinois, and her master’s thesis adviser Peter Doran. It reported the results of a two-question online survey of selected scientists. Mr. Doran and Ms. Zimmerman claimed “97 percent of climate scientists agree” that global temperatures have risen and that humans are a significant contributing factor.

The survey’s questions don’t reveal much of interest. Most scientists who are skeptical of catastrophic global warming nevertheless would answer “yes” to both questions. The survey was silent on whether the human impact is large enough to constitute a problem. Nor did it include solar scientists, space scientists, cosmologists, physicists, meteorologists or astronomers, who are the scientists most likely to be aware of natural causes of climate change.

The “97 percent” figure in the Zimmerman/Doran survey represents the views of only 79 respondents who listed climate science as an area of expertise and said they published more than half of their recent peer-reviewed papers on climate change. Seventy-nine scientists—of the 3,146 who responded to the survey—does not a consensus make.

They go on, but I don’t want to reprint the whole article here. Besides the more important point is that consensus — manufactured or otherwise — is not how science is done. “Settled science” — another concept Mair invokes — is an oxymoron. The whole point of science is to unsettle what we know at any given moment. Personally, I am more open to the claim that global warming is happening and is a potential problem than some of my friends on the right (my views line up pretty well with Matt Ridley’s for what that’s worth). But when I listen to people like Mair invoke the Union of Concerned Scientists and deny objective facts by hiding behind the skirts of a bogus statistic, it gives me no confidence that these are the kinds of people who should have anything to do with formulating public policy.

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