Scientists have warned that the Atlantic Meridional Overturning Circulation (Amoc), a critical ocean current system, is significantly more likely to collapse than earlier estimates suggested. New research indicates that climate models predicting the most severe slowdown are the most realistic, raising concerns about catastrophic consequences for Europe, Africa, and the Americas.
The Amoc, which transports warm tropical water northwards, is already at its weakest in 1,600 years due to climate change. The study, published in Science Advances, combined real-world ocean observations with climate models to reduce uncertainty. It found that under moderate emissions reductions, the Amoc could slow by 42% to 58% by 2100, a level almost certain to trigger a collapse.
A collapse would have severe impacts: shifting tropical rainfall belts, causing extreme cold winters and summer droughts in Europe, and adding up to one metre to sea level rise along the Atlantic coast. Dr Valentin Portmann, lead author from Inria in France, said the findings show the Amoc is closer to a tipping point than previously thought.
Professor Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research described the results as “very concerning”, noting that the pessimistic models now appear realistic. He warned that the tipping point could be reached by mid-century, and that a collapse must be avoided “at all costs”. The study identified surface salinity in the South Atlantic as a key factor in improving model accuracy.
