Researchers, hunting for climate consensus, find it among scientists

Posted: May 23, 2013

Written by

Evan Lehmann, ClimateWire
Environment

There's a "minuscule" amount of climate skepticism among scientists studying global warming, according to new research that contrasts starkly to the opinions of a large segment of the public that sees no consensus among experts.

Ninety-seven percent of scientific study summaries, known as abstracts, examined by a team of researchers say that climate change is being caused by human activity, the researchers found. Nearly 4,000 abstracts published between 1991 and 2011 were examined.

"Our analysis indicates that the number of papers rejecting the consensus on [man-made global warming] is a vanishingly small proportion of the published research," says the resulting study, which appeared yesterday in the journal Environmental Research Letters.

The findings underscore the public's mistaken belief that there's widespread disagreement among scientists around the cause of rising temperatures. A Pew poll from last October found that 45 percent of respondents think scientists agree that climate change is man-made. Forty-three percent said they don't.

That gap is often blamed on the outsized influence of skeptical scientists, who claim that they're part of a large coalition that sees little warming and even less danger. But the researchers say less than 3 percent of the climate papers they reviewed dismiss humanity's impact.

In a follow-up survey with 1,189 scientists, the support for man-made impacts was just as high: 97 percent said humans were the cause of climate change.

Mark Richardson, a doctoral student in meteorology at the University of Reading in the United Kingdom who co-authored the paper, said the findings could reinforce other research with similar conclusions.

"Hopefully this can be used if a normal person wants to know what scientists think," he said. "We now have a pretty strong and pretty definitive answer."

'It's not a matter of what the facts are'

The notion of climate consensus is a topic of dispute for think tanks and lawmakers who don't believe in climate change, or have political reasons not to.

The Heartland Institute, a libertarian outfit in Chicago, regularly denies the findings of peer-reviewed studies concluding that a large majority of scientists see climate change as a proven point. So do some lawmakers.

Last month, Rep. Chris Stewart (R-Utah), chairman of the House Science, Space and Technology Subcommittee on Environment, said that the findings of one study have been "repeatedly discounted" in an opinion piece published by The Salt Lake Tribune.

He was referring to a survey in 2009 of 10,000 experts identified by the American Geological Institute. Of the 3,146 scientists who responded to a question about whether human activity has been a significant factor in changing temperatures, 82 percent said yes.

Stewart focused on a different number: 97 percent of climate scientists who answered that question said climate change is man-made. The lawmaker claims that the sample size is too small to be accurate. Seventy-seven climate experts responded to the man-made question, and 75 agreed that humans are playing a role.

Peter Doran, who studies climatic impacts on ice at the University of Illinois, Chicago, and co-authored the 2009 survey, says yesterday's paper reinforces past findings on the consensus question. But he doesn't think it will persuade the disbelievers.

"It's not about what the facts are," he said of his critics. "It's about trying to win the argument. I don't know how those people are ever going to change their mind. No matter what, they just won't see the data, they won't see the consensus among the scientists."

No consensus -- on specific impacts of climate change

Others believe that a newly emerging dissonance among scientists is confusing the public about the level of consensus on man-made climate change -- even though there's near-uniform agreement on it.

Martin Hoerling, a meteorologist who studies climate dynamics at NOAA's Earth System Research Laboratory, believes that people see scientists disagreeing about the impacts of climate change on extreme weather and assume that global warming isn't real. In fact, it is real, he said, even if it doesn't affect every storm.

For example, Hoerling released a study recently finding that climate change didn't cause last year's drought. But temperatures are still rising, he said, and future impacts are certain.

"It's one thing to talk about the global average temperature and be very, very confident that that's rising since the 19th century because of human influence," he said. "But then it's the pragmatic question of well, what does this mean for me locally? Do I have to wear a rain slicker in the morning more often or not?"

In other words, scientists have moved beyond asking whether climate change is happening and into harder questions, like how is it affecting individual storms.

"Here, you start getting into a tremendous amount of uncertainty in the scientific dialogue," Hoerling said. "Because the evidence of greenhouse warming on storms happening in your backyard is very weak. So there the scientific consensus is not the 97 percent spoken about in this paper."

Hoerling is an expert on climate attribution, which tries to establish whether individual weather events were worsened by climbing temperatures.

Katharine Hayhoe, an atmospheric scientist at Texas Tech University, applauded the study released yesterday for expanding on similar research by Naomi Oreskes, a history professor at the University of California, San Diego.

"It shows, once again, that there is overwhelming consensus in the published, peer-reviewed literature regarding the reality of a changing climate and the role of human activities in driving that climate," Hayhoe said in an email.



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