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https://www.theguardian.com/environment/2026/apr/15/critical-atlantic-current-significantly-more-likely-to-collapse-than-thought>
"The critical Atlantic current system appears significantly more likely to
collapse than previously thought after new research found that climate models
predicting the biggest slowdown are the most realistic. Scientists called the
new finding “very concerning” as a collapse would have catastrophic
consequences for Europe, Africa and the Americas.
The Atlantic meridional overturning circulation (Amoc) is a major part of the
global climate system and was already known to be at its weakest for 1,600
years as a result of the climate crisis. Scientists spotted warning signs of a
tipping point in 2021 and know that the Amoc has collapsed in the Earth’s past.
Climate scientists use dozens of different computer models to assess the future
climate. However, for the complex Amoc system, these produce widely varying
results, ranging from some that indicate no further slowdown by 2100 to those
suggesting a huge deceleration of about 65%, even when carbon emissions from
fossil fuel burning are gradually cut to net zero.
The research combined real-world ocean observations with the models to
determine the most reliable, and this hugely reduced the spread of uncertainty.
They found an estimated slowdown of 42% to 58% in 2100, a level almost certain
to end in collapse.
The Amoc is a major part of the global climate system and brings sun-warmed
tropical water to Europe and the Arctic, where it cools and sinks to form a
deep return current. A collapse would shift the tropical rainfall belt on which
many millions of people rely to grow their food, plunge western Europe into
extreme cold winters and summer droughts, and add 50-100cm to already rising
sea levels around the Atlantic.
Dr Valentin Portmann, at the Inria Centre de recherche Bordeaux Sud-Ouest in
France and who led the new research, said: “We found that the Amoc is going to
decline more than expected compared to the average of all climate models. This
means we have an Amoc that is closer to a tipping point.”
Prof Stefan Rahmstorf, at the Potsdam Institute for Climate Impact Research in
Germany, said: “This is an important and very concerning result. It shows that
the ‘pessimistic’ models, which show a strong weakening of the Amoc by 2100,
are, unfortunately, the realistic ones, in that they agree better with
observational data.”
He added: “I now am increasingly worried that we may well pass that Amoc
shutdown tipping point, where it becomes inevitable, in the middle of this
century, which is quite close.”
Rahmstorf, who has studied the Amoc for 35 years, has said a collapse must be
avoided “at all costs”. “I argued this when we thought the chance of an Amoc
shutdown was maybe 5%, and even then we were saying that risk is too high,
given the massive impacts. Now it looks like it’s more than 50%. The most
dramatic and drastic climate changes we see in the last 100,000 years of Earth
history have been when the Amoc switched to a different state.”"
Via Susan ****
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
