Climate Letter #2061

The principal motivation behind my writing of these letters, which began over eight years ago, has simply been to discover and explain whatever I could about things most likely to be true, mainly based on the current state of scientific knowledge. Once in awhile we get to know the absolute truth about something, like the way planets revolve around the sun, but it took humans thousands of years, or until the days of Copernicus and Galileo, to learn enough to enable us to confidently set aside all kinds of other theories. Even then there was fierce resistance to accepting evidence that had become ever more clearly established. Climate science is in a similar situation today, but with even more complications and more difficulties to deal with. We have found a handful of important bits of pure truth, like the solar cycles of Milankovitch and the ability of certain “greenhouse” gases to make the atmosphere warmer, but that barely scratches the surface of all the other things about Earth’s climate that we feel a need to be sure about but have not yet been able to reach the ultimate goal of certainty.

The need to predict what is going to happen in the way of possible changes in climate in years to come has grown by leaps and bounds since the middle of the last century. This particular need has accelerated noticeably in the eight years since I began writing, reaching boom proportions in just the last year. Unfortunately, we still don’t have much completely indisputable knowledge to offer. We have a wide assortment of hypotheses, and many of these have been significantly improved upon over the last few years, but absolute certainty remains elusive in practically every case. On top of that, we keep having brand new things entering the picture. My intent as a writer is to know as much as possible about these things as well as the others, even before they are openly debated. It is especially important to understand the qualifications of the sources, covering both the people and the evidence they rely on. Do they offer a tentative, yet possibly valuable, roadmark toward the gaining of a final conclusion? My college professors called this procedure the “Socratic method”—today the term “Bayesian inference” is more widely employed. Given the plethora of competing hypotheses, the initial, and highly critical, step requires good judgement in making decisions about which sources are best qualified for following.

Over the last few months I have focused most of my attention on hypotheses of a scientifically fundamental type that would lead to significant changes in the way we project future temperatures.  They all happen to be in the “obscure” category, and they all lead toward potential conclusions that temperature increases are likely to be greater than what we most often hear advertised.  One of these was James Hansen’s theory of warming tied to the effects of cleaning up the pollution caused by untreated sulfur emissions when we burn coal or oil.  (See Bob Berwyn’s alert reporting about this on September 15:  https://insideclimatenews.org/news/15092021/global-warming-james-hansen-aerosols/)  Another took shape in the form of a study by Kleinen et al, published on August 12, about the difficulty of removing methane from the atmosphere: https://iopscience.iop.org/article/10.1088/1748-9326/ac1814/meta. Third, and a little closer to home, we have a theory of amplified warming based on evidence that the precipitable water contained in atmospheric rivers generates powerful greenhouse energy impacts that have been overlooked by members of the science community.  This one is worth mentioning because of the quality of the evidence itself, which I consider first class, and not the qualifications of the person who made the discovery. 

Now I’m going to add a fourth entry to this list, which I previously failed to properly catch.  It’s publication, via a study released over a year old, adds greatly to our knowledge of a subject we rarely hear about in the media.  Two of the six authors, Kevin Trenberth and Michael Mann, rank at the very top of the list of well-known veteran climate experts, and once again we have the diligence of Bob Berwyn to thank for the insightful review of the study he made at the time, based on many author interviews:  https://insideclimatenews.org/news/28092020/ocean-stratification-climate-change/.  His effort is worthy of a very close reading.  Here are some of the key passages, with my boldfacing:  “Near the surface of the ocean, global warming is creating increasingly distinct layers of warm water…..The intensified layering, called ocean stratification, is happening faster than scientists expected…..that means the negative impacts will arrive faster and also be greater than expected…..The research suggests that some of the worst-case global warming scenarios outlined in major international climate reports can’t be ruled out…..If the ocean surface warms faster and less carbon is carried to the depths, those processes along with other climate feedbacks could lead atmospheric CO2 to triple and the global average temperature could increase 8 degrees Fahrenheit by 2100…..If more and more heat stays near the surface of the ocean, the warm water will heat the atmosphere above. And if the layers of warm water slow the ocean’s uptake of carbon dioxide, more heat-trapping CO2 will stay in the atmosphere…..The study also suggests that increased layering could affect El Niño-La Niña cycles in the Pacific….. the growing stratification could suppress those cycles, “leaving the Pacific in a permanent El Niño state,” Mann added…..For now, oceans take up about a quarter of the CO2 emissions from human activity, “but prospects are for less of that as time goes on,” Trenberth said…..a warm upper ocean cannot hold as much dissolved gas, whether it’s carbon dioxide or oxygen, just like a warm soda can’t hold its fizziness.”  Again, you need to read Berwyn’s full report.  This is heady stuff.  It cannot be ignored.

Carl