[Note: This essay is abstracted from my eBook Myths: Widely Held But False Beliefs In The Climate Change Crisis, available on Amazon]
In their Fifth Assessment Report the IPCC, the ‘internationally accepted scientific authority on climate change’, gave their opinion of how much of the recent global warming was caused by human activity: ‘It is extremely likely [95-100 percent confidence] more than half of the observed increase in global mean surface temperature from 1951 to 2010 was caused by the anthropogenic [i.e. man-made] increase in greenhouse gas concentrations and other anthropogenic forcings together’. Reflecting that opinion Wikipedia states that the ‘Scientific consensus on climate change’ is that ‘the Earth is warming and… this warming is mainly caused by human activities’. It claims that 97-100% of actively publishing climate scientists endorse this opinion. Similarly, NASA claim that, ‘A consensus on climate change and its human cause exists… human activities are the primary cause of the observed climate-warming trend over the past century.’ And in an October 2020 interview on CBS’s 60 Minutes climatologist Dr Michael Mann said, ‘There’s about as much scientific consensus about human-caused climate change as there is about gravity.’ So is it actually true that 97-100% of climate scientists explicitly or implicitly endorse this key IPCC opinion?
Although science is not remotely democratic (it only needs one scientist to prove that the ‘consensus view’ is wrong and it is wrong) the fact remains that if this 97-100% consensus assertion is true then it is indeed very powerful. If the ‘internationally accepted scientific authority on climate change’ says something is almost certainly true and almost all climate scientists in the world agree then it almost certainly must be true – mustn’t it? Whilst there is undoubtedly almost total scientific consensus amongst the scientific authorities (literally dozens of scientific academies from around the world explicitly or implicitly endorse the IPCC’s opinions) that does not necessarily reflect the consensus view amongst climate scientists themselves. So what exactly is it that climate scientists agree on?
The consensus argument is epitomized by Barack Obama’s 2013 tweet that, ‘Ninety-seven percent of scientists agree: climate change is real, man-made and dangerous’. He tweeted this immediately after the publication of the most famous climate change consensus survey, Quantifying the consensus on man-made global warming in the scientific literature (John Cook et al, 2013) conducted by Skeptical Science, a small group of climate change activists, who, despite their name, are precisely the opposite of climate change skeptics (their strapline is ‘Getting skeptical about global warming skepticism’). This study examined the Abstracts from 11,944 climate science papers published over the twenty-year period from 1991 to 2011. It concluded that 97.1% of the Abstracts (that actually expressed an opinion on the causes of global warming) endorsed the view that man-made greenhouse gas emissions (or, at least, greenhouse gases) cause global warming. Although this was 97% of Abstracts, not 97% of climate scientists, it is not unreasonable to suppose that, based on this survey, about 97% of climate scientists endorse the view that man-made greenhouse gas emissions (or, at least, greenhouse gases) cause global warming. It said nothing whatsoever about how much warming those emissions were causing and whether or not such warming was ‘dangerous’. It is probably the case that at least 99.9% of people who might describe themselves as climate scientists (including those most skeptical about the climate change crisis idea) endorse the view that man-made greenhouse gas emissions (or, at least, greenhouse gases) cause global warming, i.e. some global warming. That is not in any serious dispute. The dispute is about how much global warming human activity is causing and whether or not it is ‘dangerous’. So the study revealed nothing that was not already well known and uncontroversial.
Skeptical Science summarized their findings with the statement, ‘97% of climate papers expressing a position on human-caused global warming agree: global warming is happening and we are the cause’ – where ‘we are the cause’ clearly implied ‘we are the sole cause’ instead of what it actually found, viz. that we are the cause of some of the global warming. If the study had been able to show convincingly that 97% of climate scientists endorsed the IPCC’s opinion that human activity was the predominant cause of global warming between 1951 and 2010 then that would certainly have strongly supported the view that there was almost total scientific consensus that the IPCC was right. But of all the Abstracts reviewed in this study only 0.3% explicitly endorsed that central IPCC opinion1. Even (ex-IPCC) Mike Hulme has noted that, ‘The Cook et al study is hopelessly confused… in one place the paper claims to be exploring “the level of scientific consensus that human activity is very likely causing most of the current GW [Global Warming]” and yet the headline conclusion is based on rating abstracts according to whether “humans are causing global warming”. These are two entirely different judgements.’ The recently published paper Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature (Lynas et al, 2021) claims that the consensus is actually 2% higher – but once again only actually finds a 99% consensus that human activity contributes to climate change to some extent2; in fact about 99% of the papers reviewed in this study failed to explicitly quantify the extent. A survey3 of more than 1,800 climate scientists conducted in 2015 concluded that just 43% of them would endorse the IPCC opinion about our recent predominant role in global warming (and how many of them were agreeing based primarily on their faith in the IPCC and/or their self-interest in staying ‘on message’ to the climate change crisis narrative?)
Mike Hulme has stated that, ‘Claims such as “2,500 of the world’s leading scientists have reached a consensus that human activities are having a significant influence on the climate” are disingenuous. That particular consensus judgement, as are many others in the IPCC reports, is reached by only a few dozen experts.’ Supporting that view, an independent study4 found that the views expressed by the IPCC were the consensus of a leadership cadre of just 53 (about 2%) of them, 44 of whom were very closely linked professionally, having co-authored papers with one another and so very likely to share the same opinions. The author of the study, John McLean (climate data analyst at the Australian Climate Science Coalition and an Expert Reviewer for the IPCC’s Fifth Assessment Report), concluded that ‘Governments have naively and unwisely accepted the claims of a human influence on global temperatures made by a close-knit clique of a few dozen scientists, many of them climate modellers, as if they were representative of the opinion of the wider scientific community.’
One of the most comprehensive reviews5 ever performed of surveys of the scientific consensus on climate change concluded:
- The articles and surveys most commonly cited as showing support for a ‘scientific consensus’ in favor of the catastrophic man-made global warming hypothesis are without exception methodologically flawed and often deliberately misleading.
- There is no survey or study showing ‘consensus’ on the most important scientific issues in the climate change debate.
- Extensive survey data show deep disagreement among scientists on scientific issues that must be resolved before the man-made global warming hypothesis can be validated. Many prominent experts and probably most working scientists disagree with the claims made by the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
So what is the real scientific consensus on climate change? There is almost total scientific consensus that carbon dioxide concentrations in the atmosphere are increasing, that that increase is predominantly due to human activity, that the climate system is warming, that climate change is happening and that human activity has contributed to some extent to the warming, changing climate. Note again that skeptical scientists, like Dr Roy Spencer and Dr Judith Curry and Dr Richard Lindzen, are part of this ‘scientific consensus on climate change’; the idea that they constitute the 3% of scientists who do not support the scientific consensus on climate change is a false idea, misrepresenting what the ‘scientific consensus on climate change’ actually is6. This misrepresentation is designed to bolster the ‘climate change crisis’ narrative and to marginalize and neutralize the skeptical scientists by making their views appear to fall far outside the overwhelming consensus view, even though they actually share that consensus view. Basically, the ‘consensus’ breaks down over the issue of whether or not human activity has been predominantly responsible for recent warming – and whether or not that warming is ‘dangerous’. The power of the false ‘97% scientific consensus that human activity has been predominantly responsible for climate change’ meme, perpetuated by Wikipedia, NASA, Facebook (and many others) is that it can be used very effectively to strangle at birth any debate about the science. As Dr Richard Lindzen has put it, ‘The claim is meant to satisfy the non-expert that he or she has no need to understand the science. Mere agreement with the 97 percent will indicate that one is a supporter of science and superior to anyone denying disaster. This actually satisfies a psychological need for many people.’
So if we return to Dr Michael Mann’s statement that, ‘There’s about as much scientific consensus about human-caused climate change as there is about gravity’ this is very disingenuous. Whilst there is almost total scientific consensus that climate change is ‘real’ and happening and that there has been some human-caused influence, there is no such scientific consensus over the extent of the human-caused influence and whether or not it could reasonably be described as ‘dangerous’, let alone a ‘crisis’.
1 Legates et al. (2015), Science & Education and ‘Consensus? What Consensus?’, GWPF Note 5, thegwpf.org, September 2013 and ‘Richard Tol’s Excellent Summary of the Flaws in Cook et al. (2013) and ‘The Infamous 97% Consensus Paper’, wattsupwiththat.com, 26 March 2015 and ‘The Cook ‘97% consensus’ paper, exposed by new book for the fraud that it really is’, wattsupwiththat.com, 12 March 2016
2 ‘Cooked Up Consensus: Lynas et al “Should Rather Be Classified As Propaganda, Bad Science”’, wattsupwiththat.com, 26 October 2021
3 Bart Strengers, Bart Verheggen and Kees Vringer (2015), Climate Science Survey, Questions and Responses, PBL Netherlands Environmental Assessment Agency, pp 1 – 39
4 ‘Prejudiced authors, prejudiced findings’, John McLean, (Science and Public Policy Institute), July 2008
5 Why Scientists Disagree About Global Warming (2015) – Craig D. Idso, Robert M. Carter, S. Fred Singer
6 ‘Study: 3% Contrarians Derailing the 97% Climate Consensus’, wattsupwiththat.com, 18 December 2021