Here are some excerpts.
------------------------------------------The Intergovernmental Panel on Climate Change (IPCC) is an important organization with a primary purpose to assess the scientific literature on climate in order to inform policy. The IPCC spans the physical sciences, impacts, adaptation and vulnerability and economics. I have often stated that the IPCC is so important that if it did not exist we’d need to invent it, because the challenge of climate change presents significant risks. As a consequence, both mitigation and adaptation responses must be a priority. Rigorous scientific assessments are thus needed to inform policy making. Earlier this week the IPCC’s Working Group 2 (WG2) report was released on impacts, adaptation and vulnerability — Working Group 1 on the physical sciences was released last year and Working Group 3 on economics will come later this year.
Regrettably, the IPCC WG2 has strayed far from its purpose to assess and evaluate the scientific literature, and has positioned itself much more as a cheerleader for emissions reductions and produced a report that supports such advocacy. The IPCC exhorts: “impacts will continue to increase if drastic cuts in greenhouse gas emissions are further delayed – affecting the lives of today’s children tomorrow and those of their children much more than ours … Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future.”
The focus on emissions reductions is a major new orientation for WG2, which previously was focused exclusively on impacts, adaptation and vulnerability. The new focus on mitigation is explicit, with the IPCC WG2 noting (1-31) that its focus “expands significantly from previous reports” and now includes “the benefits of climate change mitigation and emissions reductions.” This new emphasis on mitigation colors the entire report, which in places reads as if adaptation is secondary to mitigation or even impossible.
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Allow me to go into the weeds just briefly (on Twitter I document many such journeys). The WG2 finding about about increasing damages from floods relies on three papers (Hirabayashi et al. 2021, Dottori et al. 2018 and Alfieri et al. 2017) . . .
But when you actually go to these three studies, you find that they are not in fact projecting future damages, as claimed by WG2. They are instead exploring what would happen if climate changes projected for 2100 are imposed upon current society. These studies have in fact eliminated the possibility of adaptation in projecting the future. This is of course ridiculous as projection and of little use in a report about adaptation.
Even worse, each of the three studies utilizes the out-of-date and implausible extreme RCP8.5 scenario to project climate changes for 2100. So not only is society frozen in time, unable to adapt — which is clearly implausible, but future climate change is projected based on an extreme scenario that is also implausible. Implausibility built on implausibility offers no practical insight as to the role of adaptation in reducing vulnerabilities and increasing resilience. We might expect this sort of thing from a passionate advocacy group spinning science for theatrical effect, but not the IPCC.
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Of course, adaptation has long been viewed as problematic in climate policy and politics. The example above indicates why that is so — rather than supporting an apocalyptic view of ever-worsening impacts as a simple function of temperature increases, adaptation opportunities allow for positive human outcomes even as the climate changes. The WG2 misrepresentation of the literature of flooding is repeated throughout the report for other phenomena. Adaptation is often ignored or minimized in favor of presenting impacts as worsening a function of ever-increasing temperatures. In reality, adaptation has great potential to result in positive human futures at a wide range of levels of future emissions and temperature changes. Mitigation and adaptation are both important and the IPCC WG2 did itself and us a huge disservice by adding mitigation to its focus.
And it gets even worse. The RCP8.5 scenario which showed up in the case of flooding above is infused throughout this report. In fact, RCP8.5 plays a greater role in this report than any past IPCC report (the table below shows a count of each scenario explicitly mentioned in the report). This matters because RCP8.5 and similar extreme scenarios are now widely understood to be implausible. The IPCC Working Group 1 even acknowledged last year that such extreme scenarios are viewed as low likelihood with scenarios such as RCP4.5 more likely. Even so, RCP8.5 dominates the WG2 report’s outlook on the future (with RCP4.5 often improperly presented as mitigation success — on current policies the world is presently on track to undershoot RCP4.5 outcomes).
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In fact, it is puzzling why it is that as scientific literature has accumulated indicating that such extreme scenarios are implausible — e.g., a 2017 study concluded, “RCP8.5 should not be a priority for future scientific research” — the IPCC has chosen to increase its reliance on these discredited scenarios.
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