The consensus gap of climate change perceptions

In case anyone is still in any doubt about the consensus among climate scientists on the existence of anthropogenic (man-made) global warming, the definitive study is still one published in the journal Environmental Research Letters (one of the Institute of Physics' journals) back in May 2013 by a team led by John Cook.

The study, entitled Quantifying the consensus on anthropogenic global warming in the scientific literature, concluded that, among published abstracts that expressed a position either way, 97% of them endorsed the consensus position that humans are causing global warming. Although three years old now, the study has been downloaded half a million times, four times more than any other IoP study, and it is considered by most to be rigorous and conclusive and pretty much the last word on the subject.

To address various attacks and misrepresentations of the original study, a follow-up paper, called Consensus on Consensus: a synthesis of consensus estimates on human-caused global warming, was published in April 2016, also by Cook et al., which looked at seven previous climate consensus papers. This paper concluded that, depending on exactly how you measure the expert consensus, the consensus among publishing climate scientists that humans are responsible for climate change is somewhere between 90% and 100%, with most of the studies finding a consensus of around 97% (that number again), and furthermore that the greater the climate expertise among those surveyed, the higher the consensus on human-caused global warming. This follow-up paper is now the second-most read paper in Environmental Research Letters after the original 2013 paper.

But, as The Guardian reports, thanks to a concerted decades-long misinformation campaign by the fossil fuel industry and some unscrupulous politicians, as well as a certain amount of false balance in media climate coverage, the public perception remains that just half to two-thirds of experts agree on human-caused global warming. This difference between the actual consensus and the public's perception of the consensus has become known as the "consensus gap". Although the consensus gap has modestly shrunk over the last few years, mainly due to increasingly accurate media coverage, it is still significant. For example, according to a March 2016 study, only 11% of Americans understand that nearly all climate scientists (here defined as more than 90%) are convinced that human-caused global warming is happening.

Of course, some contrarians (here is just one example) continue to propagate the myth that there is no consensus, or that a growing number of scientists are rejecting the consensus, so the public's confusion is perhaps understandable. I can only imagine the exasperation of the experts in this field that, after all their hard work and their attempts at engaging the general public on a hugely important issue, a whole lot of people just plain don't believe them.