North Atlantic Cooling Southeast of Greenland Continues as Studies Differ on Cause

A region of the north Atlantic southeast of Greenland has cooled by as much as 1°C relative to the 1951-80 average over the past 150 years, even as Earth's surface has warmed overall. @NewScientist reported that this area, known as the cold blob, shows cooling extending to 1000 metres depth.

Stefan Rahmstorf at the Potsdam Institute for Climate Impact Research and colleagues examined climate reanalyses drawn from satellite, buoy and ship observations.

They found heat loss from the ocean surface in the region has decreased since 1955, indicating the Atlantic Meridional Overturning Circulation is transporting less heat northward. Rahmstorf stated that winds and clouds explain only a modest fraction of the warming hole.

"Even if, in some modelling approaches, it seems possible that the cold blob is caused by the atmosphere, in fact, the data show it is caused by the ocean," he said.

The study, published in Geophysical Research Letters with DOI 10.1029/2025GL118383, concludes Atlantic Ocean circulation has already been changing for decades. Rahmstorf added that a shutdown of the subpolar gyre could reduce temperatures in the UK and nearby countries more rapidly than a full AMOC collapse, with serious climate impacts in western Europe possible as early as the 2040s.

Earlier research reached different conclusions.

A 2022 study by Chengfei He at Northeastern University linked the cold blob to a northward shift of the jet stream driven by Arctic warming. A 2021 study attributed most of the cooling to stronger winds.