May 16, 2015, by Tim Radford
Ironic message in graffiti painted on a wall in London.
Image: Matt Brown via Flickr
New study indicates that loud dissent from contrarians may prompt some researchers to soften their language about the threats of climate change. LONDON, 16 May, 2015 − Climate change denial by contrarians claiming that global warming has stopped, is a natural cycle rather than a consequence of human action, or is simply a hoax or conspiracy can take its toll of climate scientists too. A new study in Global Environmental Change suggests that the loudest voices of dissent can affect the way researchers who have separately and repeatedly confirmed the reality of global climate change then talk about their own research. Scoffing by contrarian voices can lead researchers to over-emphasise the inevitable scientific uncertainties, or over-react to claims of alarmism, or even adopt some of the contrarian language – chief of which has been talk of a “pause” or “hiatus” in global warming in the 21st century.
Stephan Lewandowsky, professor at the University of Bristol School of Experimental Psychology in the UK, and colleagues from the US and Australia call the problem “seepage”. That is, the language of the contrarians has seeped into scientific discourse. The researchers identify three psychological mechanisms, which they call “stereotype threat”, “pluralistic ignorance” and “third-person effect”. The first acts as a behaviour response: stereotype climate scientists as alarmist and this triggers a natural reaction to avoid the stereotype and downplay the climate threat, or at least not highlight the risks.
“The public has a right to be informed of risks, even if they are alarming”
Pluralistic ignorance follows when a noisy minority opinion gets disproportionate play in public debate − that is, when people who thought they were in a majority begin to feel inhibited. The third-person effect is the assumption that persuasive communications might persuade other people, but not the experts. In fact, there is evidence that even experts can be subtly affected by such talk. Professor Lewandowsky says: “It seems reasonable to conclude that the pressure of climate contrarians has contributed, at least to some degree, to scientists examining their own theory, data and models, even though all of them permit – indeed expect – changes in the rate of warming over any arbitrarily chosen period. “We scientists have a unique and crucial role in public policy to communicate clearly and accurately the entire range of risks that we know about. The public has a right to be informed of risks, even if they are alarming. “Climate scientists have done a great job in pursuing their science under great political pressure, and they have tirelessly rebutted pseudoscientific arguments against their work. “However, sometimes scientists have inadvertently allowed contrarian claims to frame the language of their scientific thinking, leading us to overstate scientific uncertainty and under-communicate knowledge.” A second study by US scientists recently confirmed that, in fact, scientists have communicated the knowledge. They have certainly done so to a US legislature rich in Republican representatives who make a point of challenging or dismissing the climate science consensus. Contrarian voices occasionally claim that the scientific community is “divided” − but such division was not on show in evidence presented to the US Congress.
Xinsheng Liu, associate research scientist at Texas A&M University, and colleagues report in the journal Climatic Change that they analysed 1,350 testimonies delivered to 253 congressional hearings from 1969 to 2007. Of the expert witnesses who expressed a view, 86% said that climate change was happening, and 78% said it was a consequence of human activity. Most significantly, 95% of those scientists who gave testimony supported action to combat climate change. So a “supermajority” of scientific opinion had presented the facts to Congress, and the near-complete agreement in the science community had been consistently presented. “Possible explanations for policymakers’ contention must be based on something other than a lack of knowledge or divided scientific information,” the report’s authors conclude. – Climate News Network
Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.