Ninety to 100 percent of climate scientists agree that the planet is warming due to human activity, according to a peer-reviewed paper published Wednesday in the journal Environmental Research Letters. The study, called a "consensus on consensus," synthesizes findings from prior published research.
While there is a near-unanimous consensus among climate scientists that human activity is causing the planet to warm, public opinion in the U.S. lags far behind. Only 70 percent of Americans (79 percent of Democrats and 56 percent of Republicans) believe there is evidence for global warming, according to recent national figures. Corporate funding that seeds doubt on the science of climate change has helped create this wide disparity in beliefs on climate change between scientists and the general public, particularly Republicans, according to a recent study published in the Proceedings of the National Academy of Sciences. The Republican party's two leading presidential candidates say they do not believe in manmade global warming.
The current study comes in response to climate skeptic Richard Tol, a professor of economics at the University of Sussex in England challenging the validity of a 2013 consensus study by John Cook, a climate communication fellow at The University of Queensland's Global Change Institute in Australia. Cook's widely cited survey had found 97 percent of climate scientists agree that humans are causing climate change, mainly through the burning of fossil fuels. Cook also authored the current study with other researchers who have previously published a total of seven peer-reviewed studies on the consensus of human-caused climate change.
The new study reaffirms Cook's prior work. The 90 to 100 percent range in the current study is a result of slight variations in the wording of the question, as well as the timing and sampling methodology used when surveying scientists or analyzing their published research.
"No matter how you slice or dice it, you still come up with essentially the same result," Naomi Oreskes, a history of science professor at Harvard University and co-author of the study, said. "The vast, vast majority of scientists are on board on this issue."
Tol came to a different conclusion, using results from surveys of non-experts such as economic geologists and what the current study describes as a "self-selected group of those who reject the consensus." At one point in his critique of Cook's 2013 study, Tol assumed that published sources that do not explicitly state the cause of global warming count as a non-endorsement of the science. If applied elsewhere, this approach would "reject consensus on well-established theories such as plate tectonics," the current study concluded.
"What this latest study shows, definitively and authoritatively, is that the scientific consensus behind human-caused climate change is overwhelming," said Michael Mann, director of the Earth System Science Center at Penn State University. "It is time to end the fake debate about whether or not climate change is real, human-caused, and a threat, and get on to the worthy debate about what to do about it."
Oreskes, who first published consensus data about climate change in 2004 and co-authored Merchants of Doubt, a book about the origins and persistence of climate denial, echoed the sentiments.
"It's really very sad that we still have to write a paper like this, but unfortunately we do," Oreskes said. "We've known about the science for a long time now. Can we please have a conversation about how to fix this problem?"