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Experto Crede: Climate Expertise Lacking among Global Warming Contrarians

A majority of scientists who dispute global warming lack the climatological expertise to do so
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©iStockphoto.com/Mark Poprocki

A mathematician in Alberta, an oceanographer from the Massachusetts Institute of Technology and a darling of climate change contrarians share a rare distinction in a new analysis of expertise about global warming. The three scientists are the only ones, on the basis of their work, to appear on two lists: both among researchers who are convinced of the scientific evidence for climate change and on a roll of those who are unconvinced.

Gordon Swaters of the University of Alberta, Carl Wunsch of M.I.T., and climate scientist John Christy of the University of Alabama in Huntsville all qualify for both lists thanks to various efforts to canvas the scientific community for those who dissent from the consensus on climate change as well as efforts to build that consensus. For example, Christy—who appeared in a contrarian film documentary and was identified by Sen. James Inhofe's office as a dissenter from any scientific consensus about observed global warming—also participated in preparing the United Nations' Intergovernmental Panel on Climate Change's (IPCC) Fourth Assessment Report released in 2007.*

The new analysis, published June 21 in Proceedings of the National Academy of Sciences, surveyed 908 researchers publishing in scientific journals from around the world on the subject and found that not only were those in the unconvinced camp less expert in the field, they were also less likely to be trained in the climate science.

"A physicist or geologist with a PhD is a scientist, but not a climate scientist and thus their opinions on complex climatological issues is not likely to be expert opinion," says William Anderegg, lead author of the analysis and a biologist-in-training at Stanford University. "Cardiologists, for example, don't prescribe chemotherapies for cancer, nor do oncologists claim expertise at heart surgery—they are all doctors, of course, but not experts outside of a narrow specialty."

Climate scientist Stephen Schneider of Stanford, who worked on the new analysis, admits that it is born of frustration with "climate deniers," such as physicist Freeman Dyson or geologist Ian Plimer, being presented as "equally credible" to his peers and granted "equal weight" as science assessments from the IPCC or U.S. National Academy of Sciences, both of which ascribe ongoing climate change to increasing concentrations of atmospheric greenhouse gases due to human activities. "We wanted to ask by objective measures, 'Who publishes the bulk of the new science in the refereed literature and gets cited the most: those who accept anthropogenic global warming or those who deny it?'" Schneider says.

Anderegg and his colleagues ranked the researchers based on total number of climate-related publications and found that those unconvinced by the evidence made up just 2.5 percent of the top 200 most prolific researchers, in terms of number of scientific publications. In the total sample, the final list of 93 unconvinced researchers published an average of 89 papers in total compared with an average of 408 among those researchers who accept human-induced climate change. Researchers had to publish at least 20 papers to qualify for the convinced or unconvinced lists, disqualifying roughly 80 percent of researchers from the initial list of potential "unconvinced experts" that was culled from the overall sample of 1,372.

Of course, some climate contrarians allege an active effort to prevent the publication of scientific findings that would undermine the climate change consensus and point to e-mails stolen from the University of East Anglia in England—so-called "Climategate"—that vow to "redefine what peer-reviewed literature is" to keep certain findings from appearing in the 2007 IPCC report on climate change. Those papers nevertheless made it into the final report. "It is a data-free assertion of conspiracy," argues Schneider, who has edited the journal Climatic Change since the 1970s. "They have no data on their submission to rejection rates, no data on the quality of peer reviews on them versus others."

Ultimately, the best way to make a name for oneself as a scientist is to overthrow the conventional hypothesis "but to do that it takes extraordinarily good science," Schneider notes. Climate change contrarians have yet to do this.

The researchers also found that, on the whole, the pool of climate change contrarians was older—receiving their PhDs, on average, in 1977—compared with those convinced by the scientific evidence for anthropogenic global warming—receiving their PhDs, on average, in 1987. "The general stereotype for the [unconvinced experts] is that of aging scientists far outside of their field," Anderegg says. "To some extent, we've demonstrated that on the expertise angle in this paper."

As the world—and the U.S.—struggles to determine what to do about human emissions of the greenhouse gases causing climate change, applying appropriate expertise to the problem is critical. "The American public at large are increasingly confused about the risks of human induced climate change," Anderegg says, despite efforts such as a 2004 analysis in Science that found that of 928 scientific papers surveyed, none argued for natural explanations of climate change. That's because there is a short list of scientists willing to dispute the evidence for human emissions of greenhouse gases causing climate change—and yet both governments and the media have been willing to air the views of researchers on that list. As a result, the Sunday Times of London had to issue a retraction for an article that alleged the IPCC had relied on faulty evidence for its statements about potential drought in the Amazon as well as a formal apology to ecologist Simon Lewis of the University of Leeds for misrepresenting his scientific views on the subject.

And the list of the unconvinced also does not truly include M.I.T.'s Wunsch, who finds himself on it thanks to being selectively quoted in a climate contrarian documentary, nor Alberta's Swaters, who immediately issued a retraction when he discovered his name on a letter to Canada's prime minister arguing against anthropogenic global warming. That leaves Alabama's Christy and 90 other unconvinced colleagues with various levels of expertise. But, as the PNAS analysis authors wrote: "Not all climate researchers are equal in scientific credibility and expertise in the climate system."

*Correction (6/28/10): This sentence was changed to report the correct reasons that John Christy was included in the unconvinced experts list. It originally stated Christy had signed letters dissenting from scientific consensus about observed global warming.

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