The second big part of the newly released Sixth Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC)—also known as the Working Group 2 (WG2) report—contains thousands of pages on the “impacts” of climate change, with considerable emphasis on future expectations.
The University of Colorado’s Roger Pielke Jr. demolishes it more completely than any other of the IPCC’s increasingly dubious documents. The first one, from 1990, was actually sensible, and while it clearly overpredicted warming for our age, at least it didn’t try to rewrite climate history, noting that it was likely a bit warmer prior to the Little Ice Age, back in the 17th century. The second one was mired in scandal, as the key statement—“The balance of evidence suggests a discernible human influence on global climate”—was inserted after the peer review process, and it was certainly a statement that many of those reviewers would have vigorously objected to.
From then on, it’s been a downhill roll for the IPCC, with the latest WG2 report at the bottom so far (with plenty of room to go down further).
Pielke repeatedly notes that the WG2 report ignores important scientific literature or even misquotes previous IPCC documents. Even more than earlier reports, it emphasizes an impossibly high future emissions pathway (known as RCP 8.5) that assumes a whopping 8.5 watt per square meter increase in radiational imbalance by 2100. As Pielke repeatedly observes, it’s much more likely that the increase will be around 4.5, or a bit more than half of what the IPCC touts in its new report. Pielke notes:
Remarkably, RCP8.5 is characterized in the report as a “business as usual” future, and RCP4.5 is a “low emissions future.”
In actual reality, RCP4.5 is currently thought of as an upper bound trajectory under current or stated policies & RCP8.5 is implausible
It might be worth a look into one of the key papers on future emissions, by Zeke Hausfather and Glen Peters, published in Nature in 2020. Scientific papers are usually titled in dry and descriptive fashion, but not Hausfather and Peters, whose subtitle exhorts policy wonks to “Stop using the worst-case scenario for climate warming as the most likely outcome—more realistic baselines make for better policy.”
With regard to RCP 8.5, Hausfather and Peters wrote:
Happily—and that’s a word we climatologists rarely get to use—the world imagined in RCP8.5 is one that, in our view, becomes increasingly implausible with every passing year. Emission pathways to get to RCP8.5 generally require an unprecedented fivefold increase in coal use by the end of the century, an amount larger than some estimates of recoverable coal reserves.
There’s an additional problem, which Pielke doesn’t cover in depth: Surface temperature data are so fudged now that they barely resemble the original figures. In addition, newly “revised” surface histories are statistically infilling missing data in a highly questionable fashion.
For example, it’s now a standard procedure to extend the temperature measured at the highest latitude land stations far out into the Arctic Ocean, where there are no permanent measurement sites. The problem is that much of the year the ocean is covered with ice, and there’s still a lot of ice around in September, when the ice reaches its annual minimum value.
Assignment: Take a high-quality thermometer (perhaps an electronic kitchen one) and let it settle on the ambient temperature. Then take a glass of water with only a small amount of ice in it and keep it stirred. The temperature will be right at 33⁰F, even if the “land” temperature measured outside of it is around 70⁰. That’s because a well-mixed water-ice body will stay at freezing until all of the ice is gone. But the new “infilled” data will resemble the land temperatures, despite being devoid of ice in the summer.
These and other shenanigans have successively increased the amount of global warming, either by cooling down the early years of the late 19th or early 20th century, or by warming up recent data. Who can forget how federal climatologists, in the summer of 2015, “disappeared” the heavily documented 14-year “pause” in global warming? That was in time for the Paris Accord fest held the following December. This paper was so “pal-reviewed” that it appeared with a statistical significance level (p=.10) that is an embarrassment in a quantitative analysis of physical trends.
None of these things—impossible emissions pathways, made-up data, and increasing warming from the same data—seem to bother the authors of the new WG2 report. With these and all the flaws detailed by Pielke, it seems best to simply ignore it. Further, the two calibrated global temperature records, from weather balloons (which are literally recalibrated every time they are launched), and satellites indicate recent warming rates about half of what has been forecast—a prima facie invalidation of the U.N.’s latest climate claims.