How to argue with a Scientific Consensus
We brushed up against this topic with Vanessa’s logical example examining Donald Trump’s statements about climate change. For those wondering how Trump (and others) attempt to refute the overwhelming scientific evidence that humans are indeed responsible for the perils caused by climate change, the New Republic article quoted below looks into the ‘finer’ points of their argument.
How do those who deny the scientific consensus look to make their claim? Are they attacking the validity, factual correctness, or soundness of the IPCC’s reporting on climate science? And do they have sufficient ground to be making these denials?
The main criticism of Cook’s study is that it omits the vast number of papers that take no position on global warming’s causes. That’s true: Cook’s study of the 12,000 abstracts found that 66 percent of them took no position, so he excluded them in calculating the percentage. As Cook explained in an online video, he omitted these papers because abstracts are short summaries that “don’t waste time stating something they assume their readers will already know”; just as most “astronomy papers don’t think it necessary to explain that the Earth revolves around the sun,” he said, “nowadays most climatology papers don’t see the need to reaffirm the consensus position.”
The deniers’ criticism hardly discredits his study. After all, roughly 4,000 of those abstracts did take a position, and 97 percent of them endorsed anthropogenic warming. And it’s hardly the first study of its kind.
Cook’s finding is backed by a field of literature. A paper in the journal Science published a decade earlier by Naomi Oreskes found 75 percent of peer-review literature from 1993 to 2003 agreed on man’s role in global warming. That percentage has only risen as the scientific study on climate has progressed. In June, a longtime research of the subject, National Physical Sciences Consortium director James Powell, found that 97 percent might be too low. His paper, which has not yet been published, found 99.9 percent of the field agreed in 24,000 peer-reviewed papers published in 2013 and 2014.
“The fact that each of these studies have used completely different methods to arrive at the same result demonstrates just how robust the overwhelming consensus on climate change is,” Cook said, pointing out that these studies have relied on techniques like directly surveying climate scientists, analyzing public statements, and examining peer-reviewed papers. All these approaches confirm the same point on the vast agreement.
Even if you want to ignore the consensus literature, the Intergovernmental Panel on Climate Change—which includes the most robust panel of respected climate scientists in the world—said in its most recent and fifth assessment that it has 95 percent confidence that humans are driving warming (equivalent to the scientific certainty that cigarettes cause health problems).
That’s not the only case deniers make against the 97 percent figure. They argue that if you include non-experts (academics in fields unrelated to climate change) or only look at the studies that say global warming dangerous, you’d get a much lower number. There are some obvious problems with these arguments: Shouldn’t expertise in a field matter? And how to define “dangerous” warming was outside the scope of Cook’s study. After all, the whole point of the study was to answer a simple question that cuts through the rhetoric of climate politics.
All this debate over one statistic might seem silly, but it’s important that Americans understand there is overwhelming agreement about human-caused global warming. Deniers have managed to undermine how the public views climate science, which in turn makes voters less likely to support climate action. According Gallup polling, only 60 percent of Americans think that most scientists believe climate change is occurring.