03 July 2025

We Are F%$#ed


See the blue spot south of Greenland and Iceland 
As my reader(s) may recall, I have suggested that the potential for anthropogenic climate change causing a collapse of the Atlantic Meridional Overturning Circulation (AMOC) could change climate significantly, particularly in Europe, where it could cause a temperature drop of 5-15°C (9-27°F).

The problem is that the anything near a remotely accurate measurement of the AMOC has only been done over the last few decades, so there is not good data to see how this massive current has changed. 

Total volume of the AMOC is about  18 Sverdrup (Sv) or 18,000,000 m³/s, which made observations extremely difficult in the past.

Well , a group of researchers believe that they have found a correlation between AMOC flow rate and the temperature of the cold spot in the Atlantic Ocean south of Greenland.

Given that we have surface temperature readings going back centuries for the Atlantic, this allows us to see trends, and the trends ain't good: 

For months – if not years – debate has raged among scientists over the general health of an ocean current system critical to regulating Earth’s climate – arguing over whether or not the Atlantic Meridional Overturning Circulation (or AMOC) is slowing down.

This week, researchers looking into the root cause of a centuries-old patch of cold water south of Greenland and its resistance to the overall warming trend of the Atlantic Ocean, has come to one simple conclusion. That it is.

Landing on only one explanation for the observed ocean temperatures and patterns in salinity across the region, researchers from the University of California, Riverside concluded that the AMOC – a massive current system responsible for moving warm, salty water northward and cooler water southward at depth, is indeed weakening.

“People have been asking why this cold spot exists,” said University of California, Riverside climate scientist Wei Liu, who led the study with doctoral student Kai-Yuan Li. “We found the most likely answer is a weakening AMOC.”

The AMOC acts like a giant conveyor belt, delivering heat and salt from the tropics to the North Atlantic. A slowdown in this system means less warm, salty water reaches the sub-polar region, resulting in the cooling and freshening observed south of Greenland.

………

Together, Li and Liu analysed a century’s worth of this data, as direct AMOC observations go back only as far as 20 years. From these long term records, they reconstructed changes in the circulation system and compared those with nearly 100 different climate models.

Their paper – published this week in Communications Earth & Environment – shows that only in the models simulating a weakened AMOC were outcomes generally matched to the real-world data. Models that assumed a stronger AMOC didn’t come close.

“It’s a very robust correlation,” said Li. “If you look at the observations and compare them with all the simulations, only the weakened-AMOC scenario reproduces the cooling in this one region.”

………

With limited direct data on the AMOC, temperature and salinity records provide a valuable alternative for detecting long-term circulation change, and for helping to predict future climate scenarios.

This does not bode well for our society or our planet.

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