The Science Advances study, led by Valentin Portmann in France, says corrected model biases make the forecast about 60% higher than standard climate-model averages.
Researchers warn a weaker AMOC could accelerate sea-level rise on the US northeast coast, shift tropical rainfall south, disrupt West African and South Asian monsoons, and bring colder European winters.
Observations suggest the current has already weakened 10-20% since the mid-2000s, while the study says strong emissions cuts could limit weakening to about 20% instead of around 50%.
Could the Atlantic's vital ocean current collapse decades sooner than models predict?
Will a weaker Atlantic current plunge Europe into cold while fueling floods in the US?
Why is there no global early warning system for the Atlantic's collapsing 'heartbeat'?