1} A new study resolves a debate concerning the stability of the Antarctic ice sheet, with unwanted results. Here is the review in Phys.0rg—https://phys.org/news/2022-02-debate-long-standing-antarctic-climate-mystery.html. Some excerpts, with my ital: “The research, published recently in the journal Geology, and funded by the National Science Foundation and the National Environment Research Council, lends additional weight to evidence that the Antarctic Ice Sheet is sensitive to small changes in CO2 levels, and that in the past, large portions of the ice sheet could have disappeared under CO2 levels similar to today…..Is the West Antarctic Ice Sheet sensitive to a warming climate or not? Resolving this debate is of planetary significance, since the same portions of the Antarctic Ice Sheet that collapsed in the past could raise future sea levels by 10 feet or more if they were to collapse in our own time…..this work finally brings all of the geologic information neatly into line, and suggests that large parts of the Antarctic Ice Sheet may have collapsed under climatic situations similar to today.”
2} The following chart from Berkeley Earth shows how much the globe has warmed in the last century—plus three or four years—with an update through January. I would start the uptrend at a center point of -0.3C on the chart and end it with an extension through 2022 somewhere between +0.9 and 1.0C, for a projected net gain of around 1.25C. This is basically the same as the number that is often used to represent the increase since the beginning of the industrial era around 1750, leading to a belief that there was no meaningful increase for the first 170 years of the new era. How can this be explained in radiation terms, and what caused the significant change of pace that occurred after 1920?
The best answer I can give to my two-part question is that prior to 1920 the vast majority of fossil fuel combustion was in the form of coal and oil. These are both ‘dirty’ fuels, so-named because of the high amount of sulfur gases they emit when burned, and they were even dirtier back then, on average, they are today. The sulfur gases are instrumental in creating sulfate aerosols that are known to interact with clouds and brighten the top surfaces of these clouds, thereby reflecting more sunlight, possibly enough to fully offset the greenhouse energy effect of the CO2 emissions from the fossil fuels. At least that’s what an expert on these matters, James Hansen, keeps telling us, without having much-wanted access to final proof in the way of real measurements.
What happened after 1920 is that natural gas combustion began to enter the picture in large quantities, as pipeline service to homes and businesses came into being. This really took off in the thirties. I lived in a small town in Minnesota back then, and can remember how happy people were when the pipeline came through. The gas was cheap and there was no longer any need to keep struggling with coal furnaces. When gas is burned the CO2 that is given off can go right to work at warming things up, without being offset by more cloudtop brightening from additional aerosols.
In recent years, while a lot of dirty coal and diesel oil, the worst of which is bunker fuel, are still being burned in some parts of the world, much has been done to clean up the remainder. Plus, of course, natural gas is in great demand as a replacement for coal in the industrial sector, so some of the ‘old’ CO2 that has patiently remained in the atmosphere is no longer being offset to the same extent as before. This activity can largely explain why global warming has accelerated over the last eight years (above chart, counting this year), and why it probably needs to be taken into account for the next few decades as well. Scientists like Roger Pielke Jr. (see yesterday’s letter) have good reason to bypass the UN’s 1.5C target in their projections.
Carl