Study Suggests Atlantic Conveyer Current (AMOC) Will Lose 1/3 Of Volume At 2C Rise Over Preindustrial Temperatures
The Atlantic Meridional Overturning Circulation is the main driver of northward heat transport in the Atlantic Ocean today, setting global climate patterns. Whether global warming has affected the strength of this overturning circulation over the past century is still debated: observational studies suggest that there has been persistent weakening since the mid-twentieth century, whereas climate models systematically simulate a stable circulation.
Here, using Earth system and eddy-permitting coupled ocean–sea-ice models, we show that a freshening of the subarctic Atlantic Ocean and weakening of the overturning circulation increase the temperature and salinity of the South Atlantic on a decadal timescale through the propagation of Kelvin and Rossby waves. We also show that accounting for upper-end meltwater input in historical simulations significantly improves the data–model agreement on past changes in the Atlantic Meridional Overturning Circulation, yielding a slowdown of 0.46 sverdrups per decade since 1950.
Including estimates of subarctic meltwater input for the coming century suggests that this circulation could be 33% weaker than its anthropogenically unperturbed state under 2 °C of global warming, which could be reached over the coming decade. Such a weakening of the overturning circulation would substantially affect the climate and ecosystems.
EDIT (paywalled)
https://www.nature.com/articles/s41561-024-01568-1
Ed. - In case you're wondering what a Sverdrup is, it measures the volume of water in motion. 1 Sverdrup is 1 million cubic meters per second, so the current has lost 3.2 million cubic meters per second in flow since 1950.
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The planet has been through some narly shifts over the ages/epochs...and not a lot of them were condusive for human life. So we'll go the way of the dinos, and the Earth will re-regulate over many more epochs...
It's so funny to me to see how arrogant our current human mindset is. Like we can stop these huge natural shifts from happening. The only reason we've fucked things up so badly is the overpopulation and mass release of carbon from our expansion over the planet. It reminds me of the line from The Matrix where Agnet Smith describes humans as nothing more than a virus. As I am studying Anthropology, and seeing how early civilizations lived within and outside of their means, I can fully appreciate the concept. 
The next 50 years are going to be a very bumpy ride. All the models that give us 100 years are bullshit, we're circling the drain as a species...
In Novacene, James Lovelock (probably best known for the “Gaia Hypothesis”) points out that Earth is no longer in the sun's “habitable zone” (AKA “Goldilocks zone.”) As our sun has aged, it has gotten hotter. A astronomer looking at our planet from a great distance would dismiss it as not being able to support life, due to its proximity to the sun. The most likely candidate in the solar system would be Mars (which is dead.)
The only reason we are able to survive is that green plants have regulated the temperature, by keeping the level of “greenhouse gases” remarkably low.
At this point, life might not reemerge. He compared it to an old woman who early in her life was able to survive various serious illnesses (analogous to mass extinctions) but may now be susceptible to a bad cold. (The old girl can’t “bounce back” like she used to.)
and then I read this forum and the feeling that we are in horror/sci fi movie with no good ending jumps into my gut. I admire the resilience of the contributors to this forum who are truth tellers.
