Sunday, May 5, 2024

#126 / AOMC

Yesterday, I wrote about AOC. Today, I am writing about the AOMC. 

I am pretty sure that everyone who might be reading this blog posting knows all about AOC. I didn't really need to spell that out yesterday (although I did), and I don't think I really need to spell it out again, right here. However, I am not nearly as sure that people know about the AOMC. Thus, let me spell out that acronym, right now: Atlantic Meridional Overturning Circulation (AOMC). 

A representation of the AOMC is found above. The AMOC is a system of ocean currents that circulates water within the Atlantic Ocean, bringing warm water north and cold water south. In the website I just linked, the National Ocean Service, a division of NOAA (the National Oceanic and Atmospheric Administration), provides the following, rather benign, statement about the possibility that the AMOC may be slowing down: 

Is the AMOC slowing down?
As our climate continues to change, is there a possibility that the AMOC will slow down, or come to a complete stop? While research shows it is weakening over the past century, whether or not it will continue to slow or stop circulating completely remains uncertain. If the AMOC does continue to slow down, however, it could have far-reaching climate impacts. For example, if the planet continues to warm, freshwater from melting ice at the poles would shift the rain belt in South Africa, causing droughts for millions of people. It would also cause sea level rise across the U.S. East Coast.

This statement does not come across as too alarming, at least the way I read it (though it is certainly not good news that continued global warming could cause "droughts for millions of people"). And maybe it would make sense to be at least a little alarmed, since NOAA's home page on the internet (as of March 18, 2024) informs us that "Earth just had its warmest February on record." 

Guy R. McPherson, who is a professor emeritus of natural resources and ecology and evolutionary biology at the University of Arizona, is much more alarmist than NOAA and the National Ocean Service. The headline on one of his recent blog publications asks this question: "Will AMOC Kill Us All?" Here is an excerpt:

It is no exaggeration to claim that the AMOC is critical to the continued retention of habitat for life on Earth. It is a complex tangle of currents that, among other things, works like a giant conveyor belt that transports warm water from the tropics toward the North Atlantic. At this point, the water cools and becomes saltier. It therefore sinks deep into the ocean before spreading south. Importantly, the AMOC contributes to the regulation of global weather patterns. Its collapse would trigger extreme winters and rising sea levels in western Europe and the northeastern United States. Further from home, a collapsed AMOC would shift the timing and magnitude of the tropical monsoon.

More than 12,000 years ago, the rapid melting of glaciers caused the AMOC to shut down. Within a decade, temperature fluctuations in the Northern Hemisphere reached 10-15 degrees Celsius, or 18-27 degrees Fahrenheit. The president of the Woods Hole Oceanographic Institution ... said the shutdown of the AMOC “would affect every person on the planet – it’s that big and important.

The research study referenced by CNN was published on 25 July 2023. The title is Warning of a forthcoming collapse of the Atlantic meridional overturning circulation....

Skipping to the final sentence of the Introduction in the peer-reviewed paper, we find this sentence: “In this work, we show that a transition of the AMOC is most likely to occur around 2025-2095 (90% confidence interval).” The 70-year range from 2025 to 2095 leaves a lot to be desired. After all, abundant evidence indicates we will lose habitat for human animals long before 2095 and also long before 2050. Evidence upon which I have depended for many years indicates we likely will not survive until 2030. However, if the predictions of an ice-free Arctic Ocean by renowned professors at Harvard and the University of California (San Diego) are nearly correct, then our continued survival likely will cease before 2026 (emphasis added).

Gee, game over by 2026! That gives us two years! That is pretty grim!

McPherson is well-known as a climate cassandra, having predicted the extinction of human life within ten years. Thus, his thoughts about the AMOC are certainly consistent with his overall views. McPherson, however, is definitely not alone in predicting some dire consequences related to the slowing down or failure of the AMOC. Richard Nolthenius, PhD, Chair of the Astronomy Department at Cabrillo College and deeply engaged with climate science, has recently written to climate activists at UCSC as follows: 

I'm more and more convinced that we absolutely will shut down the global ocean thermohaline circulation. It's shut down in the past with much milder forcing. And coupled with the unprecedented rise in CO2 and Earth Energy Imbalance, is mass-extinction-level forcing unless we very rapidly reverse this. And I don't mean meeting mild, pro-economic promises which always seem to be a decade past the anticipated funeral (or deep retirement to his bunker in New Zealand) - of the promisers (emphasis added).

We are, Nolthenius says, coming up to a possible climate "tipping point." And speaking of tipping points, the slowing or shut down of the AOMC isn't the only potential tipping point related to ongoing global warming. Here is a link to a discussion of NINE possible tipping points.

What's my point, here? My point is that we need to admit to ourselves that life "as we have known it" is almost certainly going to change, and change dramatically, and quite possibly change extrremely rapidly. If that is true - and my point is that this is exactly what we should anticipate - then this will make necessary a total reconfiguration of how we live. We have acted as though we could ignore the total dependence of our human world on that other world, the "World That God Made," the "World of Nature," and since Nature does "bat last," as Guy McPherson likes to say, we are going to have to be prepared to change our human arrangements to reflect the natural limits we have been ignoring. 

Organizing ourselves to do that is a mammoth "political" project. Building our political capabilities is going to be required. Let's face that fact. It's time to start building our political ability to make the kind of truly significant social and economic changes that will be required (unless we're willing to stipulate to the Guy McPherson "we're doomed" view of the future of the human race).

I, personally, am not willing to stipulate that we're doomed. I hope you're not, either!

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