A new study finds that the scientific consensus that humans are altering the climate has passed the 99.9% level.
The degree of scientific certainty about the impact of greenhouse gases is now similar to the level of agreement on evolution and plate tectonics, the authors say, based on a survey of nearly 90,000 climate-related studies. This means there is practically no doubt among experts that burning fossil fuels, such as oil, gas, coal, peat and trees, is heating the planet and causing more extreme weather.
One has to parse statistics like this carefully to see exactly what has been measured.
The latest survey of peer-reviewed literature published from 2012 to November 2020 was conducted in two stages. First, the researchers examined a random sample of 3,000 studies, in which they found only found four papers that were sceptical that the climate crisis was caused by humans. Second, they searched the full database of 88,125 studies for keywords linked to climate scepticism such as “natural cycles” and “cosmic rays”, which yielded 28 papers, all published in minor journals.
“It is really case closed. There is nobody of significance in the scientific community who doubts human-caused climate change,” said the lead author, Mark Lynas, a visiting fellow at Cornell University.
As I argue in my book The Great Paradox of Science, it is the consensus arrived at by credible experts who have studied an issue and arrived at the conclusion that there is a preponderance of evidence in favor of the theory that should be determinative. For example, I personally do not have the expertise to evaluate these complex climate models. But I do have confidence in the process by which this consensus was arrived at to support it.
One can always find skeptics to the consensus, especially when there are vested interests with deep pockets who seek to sow doubt so as to paralyze any action that would affect their economic interests. That is especially the case in the US.
The general public does not yet understand how certain experts are, nor is it reflected in political debate. This is especially true in the US, where fossil fuel companies have funded a disinformation campaign that falsely suggests the science is not yet settled, similar to the campaign by tobacco industries to cast doubt on the link between smoking and cancer.
The paper cites a 2016 study by the Pew Research Center that found only 27% of US adults believed that “almost all” scientists agreed the climate emergency was caused by human activity.
Many senior Republicans continue to cast doubt on the link between human activity and the climate crisis as market researchers have advised them to do since at least the presidency of George W Bush. According to the Center for American Progress, 30 US senators and 109 representatives “refuse to acknowledge the scientific evidence of human-caused climate change”. Several big media organisations and social networks also promote climate-sceptical views that have little or no basis in science.
One has to keep hammering away, like I do, that it is the scientific consensus among credible experts that should drive public policy, because it is always possible to produce some anomalous result. That does not mean anything by itself. It is the preponderance of evidence that is important.