A Critique of AR6

By Andy May

After more than two years of hard work, Marcel Crok, I, and 11 other scientists have finally published our critique of the Intergovernmental Panel on Climate Change (IPCC) sixth report (AR6). The entire book has been extensively peer reviewed and a low-resolution pdf of a nearly final draft of the book has been available for weeks at clintel.org. All comments received on this draft have been carefully considered and incorporated, if approved by the team, in the final book. We are a bit hard on AR6, but our criticisms are well deserved. Only the eBook is out now, the print edition should be along in a week or two. The Kindle edition is text-to-speech enabled. Available at Amazon, Kobo, and Barnes and Noble.

A Brief Summary of the Contents

The IPCC has completed its sixth climate change assessment cycle consisting of seven reports in total, collectively known as “AR6.” A team of eight scientists, in addition to several anonymous expert reviewers, from the Clintel network, have analyzed several claims from the Working Group 1 (The Physical Science Basis) and Working Group 2 (Impacts, Adaptation and Vulnerability) reports. The team and reviewers are from Spain, Canada, Italy, Germany, Norway, The Netherlands, the U.K., and the U.S. In every chapter, this book documents biases and errors in the IPCC assessment. The errors are worse in the WG2 report but are also present in the WG1 report. 

For example, the IPCC ignored 52 highly relevant peer-review articles showing that “normalised disaster losses” saw no increase attributable to climate change yet highlighted one, out of 53 papers, that claimed there is an increase in losses. That one paper is – not surprisingly – flawed, but apparently its conclusions were so appealing to the IPCC that they fell for it. The strategy of the IPCC seems to be to hide any good news about climate change. 

“We are on a highway to climate hell”, said UN-boss Guterres recently. But an in-depth look at mortality data shows that climate-related deaths are at an all-time low. Well-known economist Bjorn Lomborg published this excellent news in a 2020 peer-reviewed paper, but the IPCC chose to ignore it, see figure 17 here. 

Back in 2010, errors in the fourth WG2 report led to the investigation of the IPCC by the InterAcademy Council. This IAC Review recommended, among other recommendations, that “[h]aving author teams with diverse viewpoints is the first step toward ensuring that a full range of thoughtful views are considered.” This important recommendation is still ignored by the IPCC. One of the key recommendations in IAC Review that the AR6 authors ignored, as documented in our book, is:

“The IPCC should encourage Review Editors to fully exercise their authority to ensure that reviewers’ comments are adequately considered by the authors and that genuine controversies are adequately reflected in the report.”

InterAcademy Council Review of the IPCC, page xiv

Numerous very well documented reviewer’s comments were completely ignored in AR6, our book documents many of the more egregious of these. The AR6 Working Group 1 report is not free from bias and misleading conclusions either. The IPCC tries to rewrite climate history by erasing the existence of the Holocene Climatic Optimum, a warm period between 10,000 and 6000 years ago, by embracing a new hockey stick graph, that is the result of cherry-picked temperature proxies. They ignore temperature reconstructions that show significantly more variability in the past.

The IPCC claims there is an acceleration in the rate of sea level rise in recent decades. We show this claim is flawed because the IPCC ignores decadal natural variability in the sea level rate. We also show that the IPCC sea level tool – made available for the first time – shows a mysterious and unlikely jump upward in 2020.

Canadian economist Ross McKitrick, pointed out that all models used by the IPCC, show too much warming in the troposphere, both globally and in the tropics (where models predict a ‘hot spot’). Observed warming indicates a moderate climate sensitivity between 1 and 2.5 degrees Celsius, while the IPCC claims a climate sensitivity of 3 degrees.

On top of that, the IPCC is ‘addicted’ to its highest greenhouse gas emission scenario, the so-called RCP8.5 or now SSP5-8.5 scenario. In recent years, several papers have demonstrated that this scenario is simply not plausible and should not be used for policy purposes. Deep inside the WG1 report the IPCC acknowledges that this scenario has a ‘low likelihood’, but this very important remark was not highlighted in the Summary for Policy Makers, so the media and policy makers are unaware of this. This implausible scenario is commonly used in the report.

Our conclusions are quite harsh. We document biases and errors in almost every chapter we reviewed. In some cases, of course, one can quibble endlessly about our criticism and how relevant it is for the overall ‘climate narrative’ of the IPCC. In some cases, though, we document such blatant cherry picking by the IPCC, that even ardent supporters of the IPCC should feel embarrassed.

The AR6 report reveals that they have ignored the very important multi-decadal ocean oscillations discovered in the 1990s and 2000s (see Vinos, 2022 Ch. 11 and Wyatt and Curry, 2014) long after the IPCC had focused exclusively on anthropogenic causes. These ocean oscillations, collectively, have a large effect on our climate, but are unrelated to “non-condensing greenhouse gases.” AR6 states that:

“there has been negligible long-term influence from solar activity and volcanoes”

AR6, page 67

Yet, they acknowledge no other natural influence on multidecadal climate change despite the recent discoveries suggesting significant natural climate change, a true case of tunnel vision.

We were promised IPCC reports that would objectively report on the peer-reviewed scientific literature, yet we find numerous examples where important research was ignored. In Ross McKitrick’s chapter on the “hot spot,” he lists many important papers that are not even mentioned in AR6. Marcel Crok gives examples where unreasonable emissions scenarios are used to frighten the public in his chapter on scenarios, and examples of bias and hiding good news in his chapters on extreme weather and snowfall. Nicola Scafetta and Fritz Vahrenholt document that over 100 papers showing solar activity correlates with climate change have been ignored by the IPCC. Numerous other examples are documented in other chapters. These deliberate omissions and distortions of the truth do not speak well for the IPCC, reform of the institution is desperately needed.

Perhaps this is why, after 47 reports and 32 years, they have yet to convince a majority of the people on Earth, or in the United States, that manmade climate change is our most important and serious societal problem. Other problems are always considered more important and urgent. In a 2018 Pew Research poll climate change ranked 18th, of 19 issues in importance, in a similar 2014 poll, climate change ranked 14th in a list of priorities. A 2022 poll by the Pew Research Center also found climate change ranked 14th. In the UN My World 2015 Report, a poll of 10 million people around the world, climate change ranked dead last of 16 issues in importance. Minds are not being changed.

Are we at a fork in the road? Will the United Nations, the IPCC, and politicians finally realize that their 50-year-old hypothesis is out of date and incorporate the new natural warming forces discovered in the past thirty years into their work and projections? In the past the IPCC has fought off attempts to independently review their work. We hope our documentation of the problems in AR6 eventually leads to the necessary changes in their organization and procedures.