The claim that there is a 97% consensus among scientists that humans are the cause of global warming is widely made in climate change literature and by political figures. It has been heavily publicized, often in the form of pie charts, as illustrated by this figure from the
Consensus Project.
"The 97% figure has been disputed and vigorously defended, with emotional arguments and counterarguments published in a number of papers. Although the degree of consensus is only one of several arguments for anthropogenic climate change – the statements of professional societies and evidence presented in reports from the Intergovernmental Panel on Climate Change are others – there is data to suggest that support is lower. In this post, I attempt to determine whether the 97% consensus is fact or fiction.
The 97% number was popularized by two articles, the first by Naomi Oreskes, now Professor of Science History and Affiliated Professor of Earth and Planetary Sciences at Harvard University, and the second by a group of authors led by John Cook, the Climate Communication Fellow for the Global Change Institute at The University of Queensland. Both papers were based on analyses of earlier publications. Other analyses and surveys arrive at different, often lower, numbers depending in part on how support for the concept was defined and on the population surveyed.
This public discussion was started by Oreskes’
brief 2004 article, which included an analysis of 928 papers containing the keywords “global climate change.” The article says “none of the papers disagreed with the consensus position” of anthropogenic global warming. Although this article makes no claim to a specific number, it is routinely described as indicating 100% agreement and used as support for the 97% figure.
Cook is careful to describe his 2013 study results as being based on “climate experts.” Political figures and the popular press are not so careful.
President Obama and Secretary of State John Kerry have repeatedly characterized it as 97% of scientists.
Kerry has gone so far as to say that “97 percent of peer-reviewed climate studies confirm that climate change is happening and that human activity is largely responsible.” This is patently wrong, since the Cook study and others showed that the majority of papers take no position. One does not expect nuance in political speeches, and the authors of scientific papers cannot be held responsible for the statements of politicians and the media.
Given these results, it is clear that support among scientists for human-caused climate change is below 97%. Most studies including specialties other than climatologists find support in the range of 80% to 90%. The 97% consensus of scientists, when used without limitation to climate scientists, is false.
In the strict sense, the 97% consensus is false, even when limited to climate scientists. The 2016 Cook review found the consensus to be “shared by 90%–100% of publishing climate scientists.” One survey found it to be 84%. Continuing to claim 97% support is deceptive. I find the 97% consensus of climate scientists to be overstated."
Fact Checking The Claim Of 97% Consensus On Anthropogenic Climate Change
Scientists receive funding for proving climate change is caused by humans. They also lose their jobs and get ostracized for going against the grain.
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The work of science has nothing whatever to do with consensus. Consensus is the business of politics. Science, on the contrary, requires only one investigator who happens to be right, which means that he or she has results that are verifiable by reference to the real world. In science consensus is irrelevant. What is relevant is reproducible results. The greatest scientists in history are great precisely because they broke with the consensus."
