AMOC Slowing: Scientists Split on Collapse Risk
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- The AMOC carries roughly one petawatt of heat northward — about 50 times total global energy use — making it central to why Britain and north-west Europe are milder than their latitude would suggest.
- Prof Stefan Rahmstorf of the Potsdam Institute says he reversed his position over the past five years, now treating AMOC collapse as a more probable risk because lighter, fresher water reduces the sinking that powers the current.
- A UCL-led study of the Younger Dryas, nearly 13,000 years ago, found the Atlantic circulation was "abruptly altered," with the Gulf Stream shifting hundreds of miles north and pushing Britain into colder conditions for over a thousand years.
- The "cold blob" south of Greenland — a region refusing to follow global warming patterns — along with reduced North Atlantic salinity are described by Rahmstorf as the clearest fingerprints of AMOC weakening, though direct measurements only began in 2004.
- A severe AMOC weakening could shift storm tracks, bring colder, drier winters to the UK, and tug at the West African monsoon, tropical rainfall belts and Amazon rainfall, affecting harvests and water supplies for hundreds of millions.
- Prof Andrew Watson of the University of Exeter is cited as representing the cautious scientific view that gradual weakening is not the same as collapse.
Why it matters: Britain's mild climate is an inheritance from the AMOC, and one of the field's leading scientists says he shifted over the past five years from treating collapse as unlikely to treating it as a real risk. The same system helps dictate rainfall reaching the West African monsoon and the Amazon, so any major disruption would extend far beyond British winters.
