Almost everyone seems to accept the often quoted claim that 97% of climate scientists agree that climate change is real and man-made – but is the figure accurate?
The figure comes from a 2013 article entitled “Quantifying the Consensus on Anthropogenic Global Warming in the Scientific Literature” by John Cook et al which said that “Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming”.
Cook and his associates reviewed the titles and abstracts of 11,944 peer-reviewed articles from 1991 to 2011 with the keywords “global climate change” or “global warming.” They found 78 articles which explicitly rejected anthropogenic global warming, 40 which were uncertain, 7,930 which took no position and 3,896 articles – or 97.1% of those which took a position – which endorsed it.
The papers which “took no position” were on topics like the impact of global warming or techniques for measuring it. Why would scientists write papers on the impact or measurement of global warming if they didn’t believe that it is real? The important figure is that 78 of the 11,944 articles – or 0.06% – rejected global warming.
Furthermore, some of these papers are from a quarter of a century ago. James Lawrence Powell has repeated the exercise on papers written in 2013 and 2014. Of the 24,210 papers, only five – or 0.02% – rejected anthropogenic global warming.
So, it seems that the consensus on global warming among climate scientists is not 97% but more like 99.98%.