AMOC may weaken much faster than previously thought

A new study in Science Advances compares climate-model projections with observations and estimates a 43–58% slowdown of the Atlantic Meridional Overturning Circulation by 2100, with the best method giving about a 50% weakening at roughly 90% probability.

The Atlantic Meridional Overturning Circulation (AMOC) is showing signs of significant weakening, according to a recent peer-reviewed study. Researchers compared multiple climate-model projections with real-world ocean observations to see which projections best matched measured conditions. The study reports an estimated 43–58% slowdown of the AMOC by 2100 using the best-performing observational constraint method, with about a 90% probability of roughly 50% weakening. Scientists have long debated the AMOC's future because this circulation helps redistribute heat and influences regional climate patterns. Key findings: - The study published in Science Advances used observational constraints and estimated a 43–58% AMOC slowdown by 2100; the best-performing method gives roughly a 50% weakening with about 90% probability. - That estimated weakening is about 60% stronger than the average projection across the climate models the researchers examined. - Separate recent observations from moorings along the western North Atlantic, collected since 2004, reported weakening across multiple latitudes over the past two decades. - The researchers tested four observational constraint methods and found stronger agreement between observations and the more strongly weakening model projections. Summary: A sustained large weakening of the AMOC would be associated with substantial regional climate shifts, including changes to heat distribution, sea levels, and precipitation patterns in affected areas. Undetermined at this time.