Anthropogenic Change: 97% Climate Scientists For, 3% Against

New research says that the vast majority of the world’s active climate scientists accept the evidence for global warming as well as the case that human activities are the principal cause of it. This data comes from a new survey out this week in the Proceedings of the US National Academy of Sciences. It found that 97% of scientific experts agree that climate change is “very likely” caused mainly by human activity.

By Justin Gillis in New York Times (22 June 2010):

Many debates about global warming seem to boil down to appeals to authority, with one side or the other citing some famous scientist, or group of them, to buttress a particular argument. The tone is often, “My expert is better than yours!”

Against this backdrop, some analysts have been trying for several years to get a firm handle on where climate researchers come down, as a group, on the central issues in the global-warming debate: Is the earth warming up, and if so, are humans largely responsible?

Now comes another entry in this developing literature. William R.L. Anderegg, a doctoral candidate at Stanford University, and his fellow authors compiled a database of 1,372 climate researchers. They then focused on scientists who had published at least 20 papers on climate, as a way to concentrate on those most active in the field. That produced a list of 908 researchers whose work was subjected to close scrutiny.

The authors then classified those researchers as convinced or unconvinced by the evidence for human-induced climate change, based on such factors as whether they have signed public statements endorsing or dissenting from the big United Nations reports raising alarm about the issue. Then the authors analyzed how often each scientist had been published in the climate-science literature, as well as how often each had been cited in other papers. (The latter is a standard measure of scientific credibility and influence.)

The results are pretty conclusive. The new research supports the idea that the vast majority of the world’s active climate scientists accept the evidence for global warming as well as the case that human activities are the principal cause of it.

For example, of the top 50 climate researchers identified by the study (as ranked by the number of papers they had published), only 2 percent fell into the camp of climate dissenters. Of the top 200 researchers, only 2.5 percent fell into the dissenter camp. That is consistent with past work, including opinion polls, suggesting that 97 to 98 percent of working climate scientists accept the evidence for human-induced climate change.

The study demonstrates that most of the scientists who have been publicly identified as climate skeptics are not actively publishing in the field. And the handful who are tend to have a slim track record, with about half as many papers published as the scientists who accept the mainstream view. The skeptics are also less influential, as judged by how often their scientific papers are cited in the work of other climate scientists.

“We show that the expertise and prominence, two integral components of overall expert credibility, of climate researchers convinced by the evidence” of human-induced climate change “vastly overshadows that of the climate change skeptics and contrarians,” Mr. Anderegg and the other authors write in their paper.

Climate-change skeptics will most likely find fault with this research, as they have with similar efforts in the past. For starters, Mr. Anderegg’s dissertation advisers are Christopher Field and Stephen H. Schneider, two of the most prominent advocates of the mainstream view of climate change; Dr. Schneider is a co-author of the new paper.

The climate dissenters have long complained that global-warming science is an echo chamber in which, they contend, it is hard to get published if one does not accept the conventional wisdom that humans are heating up the planet. So they argue that it is circular reasoning to claim a broad scientific consensus based on publication track records. The mainstream researchers reject that charge, contending that global warming skeptics do not get published for the simple reason that their work is weak.

In this long-running battle over scientific credibility and how to measure it, the Anderegg paper analyzes a particularly large database of climate researchers, and therefore goes farther than any previous effort in attaching hard numbers to the discussion.

Source: www.green.blogs.nytimes.com

By Doyle Rice in USA Today (22 June 2010):

Forget the four out of five dentists who recommend Trident…. Try the 97 out of 100 scientists that believe in man-made climate change.

This data comes from a new survey out this week in the Proceedings of the National Academy of Sciences.

The study found that 97 percent of scientific experts agree that climate change is “very likely” caused mainly by human activity.

The report is based on questions posed to 1,372 scientists. Nearly all the experts agreed that it is “very likely that anthropogenic greenhouse gases have been responsible for most of the unequivocal warming of the Earth’s average global temperature in the second half of the twentieth century.”

As for the 3 percent of scientists who remain unconvinced, the study found their average expertise is far below that of their colleagues, as measured by publication and citation rates.

In the study, the authors wrote: “This extensive analysis of the mainstream versus skeptical/contrarian researchers suggests a strong role for considering expert credibility in the relative weight of and attention to these groups of researchers in future discussions in media, policy, and public forums regarding anthropogenic climate change.”

The study authors were William R.L. Anderegg, James W. Prall, Jacob Harold and Stephen H. Schneider.

The report comes as the Earth continues to sizzle in 2010. So far, through May, 2010 is the warmest year ever recorded, according to the National Climatic Data Center.

Source: www.content.usatoday.com