CLINTEL critical review of IPCC AR6

“The IPCC has omitted significant peer-reviewed literature showing that standardized disaster damage has decreased since 1990 and that human mortality from extreme weather has decreased by more than 95% since 1920. The IPCC, by sifting through the literature, has reached the opposite conclusion, claiming increased damage and mortality from human-caused climate change.”

Regarding the assessment of extreme weather events due to the fault of IPCC AR6, see also this section analysis by Roger Pielke Jr demonstrated serious errors in underreporting conclusions from papers actually cited by the IPCC.

In regards to ignoring natural climate variability, Chapters 1 (mid Holocene), 2 (Hockey sticks) and 6 (sun) are excellent.

I’ve been looking at the AR6 WGI Report quite closely, mainly focusing on specific material relevant to my new book. Climate uncertainty and risk. I was familiar with nearly all of the issues raised in the CLINTEL Report, but the material in Chapters 2 (Hockey sticks) and 4 (snow trends) was new to me. The next section focuses on Hockey Sticks.

Zombie Hockey Sticks

Shortly after the AR6 WGI was published, I discovered some twitter comments regarding the Hockey Stick revival. After wondering “What the hell is new about hockey?”, I didn’t investigate further.

Yes, Clintel Reports worked for me. Subtitles for Chapter 2:

“A big surprise in the new IPCC report is the publication of a brand new hockey stick. IPCC must again select and massage the proxy data to generate it. Studies showing greater natural climate variability are ignored.”

Excerpt from the chapter:

The PAGES 2k team specializes in climate reconstructions and back in 2013 consisted of the majority of active paleontologists. PAGES 2k Consortium (2013) published a reconstruction where parts of the first millennium were sometimes as warm as they are today.

In 2019, PAGES 2k published a new edition of temperature evolution over the past 2000 years (PAGES 2k Consortium, 2019)11. Surprisingly, it differs greatly from its predecessor. Although the database has only changed slightly, the pre-industrial part is now suddenly almost flat again. The hockey stick has been reborn.

The new hockey stick was immediately included in the AR6 report (IPCC, 2021). Among the lead authors of AR6 chapter 2 is Darrell S. Kaufman, co-author of the new hockey stick in the PAGES 2k Consortium (2019). This is probably not a coincidence.

Evidence suggests that a significant portion of PAGES 2k researchers were initially unable to technically support the new hockey stick and seems to have led the team to dispute. Meanwhile, dropouts have published a temperature curve that competes with significant variation in pre-industrial temperatures (Büntgen et al., 2020). On the basis of thoroughly verified tree rings, experts can demonstrate that summer temperatures have repeatedly reached present levels in pre-industrial times. However, the study by Ulf Büntgen and colleagues was not included in the IPCC report, even though it was published ahead of the editorial deadline.

Like its predecessor, the new PAGES 2k 2019 hockey stick relies on a variety of proxies and includes a large amount of poorly recorded tree ring data. In many cases, the temperature sensitivity of the tree ring is uncertain. For example, both PAGES 2k Consortium (2013) and PAGES 2k Consortium (2019) use tree rings from the French Alps, although tree-ring experts have previously warned that they are too complicated to use. used as a representative of the overall temperature.

In contrast, Büntgen et al. (2020) is more selective, based on a type of proxy (in this case, a tree ring) and validates each individual tree ring dataset. Their temperature aggregates for the extratropical northern hemisphere differ greatly from studies using bulk tree-ring inputs.

In some cases, PAGES 2k composites mistakenly included proxies that later turned out to reflect climate, not temperature. In other cases, outlier studies were selected in which proxies exhibit non-reproducible anomalous evolution in neighboring sites (e.g. MWP data from the Pyrenees and the Alboran Sea in PA13). . Outliers can have a number of reasons, e.g. different local growth, invalid or unstable temperature proxies, or sample contamination.

Steve McIntyre has researched the PAGES 2k proxy database in great detail and summarized his criticisms in a series of blog posts on his Climate Audit website. For example, PAGES 2k Consortium (2019) integrated tree-ring dating from northern Pakistan near Gilgit (“Asia_207”) shows extreme gains at the end. Combining data series like this strongly promotes the hockey stick geometry of the resulting temperature mixture. McIntyre analyzed the original tree-ring data and found that the sharp increase in the Asia_207 date was the result of questionable data processing. When calculating the site’s chronology using the rcs function from Andy Bunn’s dplR package, the increase sign surprisingly disappeared. In fact, the series declined during the 20th century.

Conclusion: The revived AR6 hockey stick shows how susceptible the IPCC process is to scientific bias. Cherry picking, abuse of the peer-review process, lack of transparency and the possibility of political interference have led to a gross misrepresentation of pre-industrial temperature evolution.

JC reflex

The CLINTEL report provides a much-needed critical assessment and intellectual counterbalance to the IPCC AR6.

There is a lot of good material in the AR6 WG1 Report, but there are also a lot of flaws in the Report (the AR6 WG2 Report is absolutely terrible). With any kind of serious review, or if the author pool is diverse enough, we won’t see that many types of errors. Unfortunately, the IPCC defines “diversity” in terms of gender, race, and developed countries versus less developed countries; factual diversity of thought and point of view is discarded in favor of promoting a politically authorized narrative from the United Nations.

The consensus disease was discovered by the IPCC after the publication of the first Assessment Report in 1990, which, combined with pressure from policymakers, resulted in documents that did not reflect disagreement and uncertainty. on these complex topics. The IPCC Mandatory Narrative has become very old. Worse yet, it has become increasingly irrelevant to policymaking by continuing to focus on extreme emissions scenarios and the shameful cherry picking needed to support the narrative.” climate crisis” which is very popular with UN officials.

In any event, climate policy run by the United Nations has overcome every hurdle in climate science, even the relatively alarming version reported by the IPCC. The crazy policies and deadlines associated with greenhouse gas emissions are simply at odds with the realities of our understanding of climate change and uncertainties, and with broader considerations about climate change. human health.