Overview
- Scientists reported June 15 that a persistent patch of unusually cold water south of Greenland has cooled by about 1°C over recent decades and that the anomaly now reaches well below the surface.
- New analysis in Geophysical Research Letters finds the pattern is best explained by a slowdown in the Atlantic Meridional Overturning Circulation, the system that carries warm surface water north and returns cold deep water south.
- Researchers say the cooling cannot be explained by surface winds alone because the largest drop in heat content is in the top 1,000 meters where the AMOC operates.
- The studies link part of the weakening to freshwater from accelerated Greenland ice melt, which lowers surface salinity and reduces the density-driven sinking that helps power the overturning circulation.
- Scientists warn a continued AMOC decline could shift storm tracks, cool parts of northern Europe and Greenland, and accelerate sea-level rise along portions of the U.S. East Coast, though the timing and size of those impacts remain uncertain.