North Atlantic Cold Blob Indicates Weakening of AMOC

Scientists have identified a persistent “cold blob” in the North Atlantic, a band of water south of Greenland and Iceland that has cooled by about 1 °C since 1900 despite overall ocean warming. A new study combining satellite data, ocean instruments and climate models attributes the cooling to a weakening of the Atlantic Meridional Overturning Circulation (AMOC), the ocean conveyor that transports heat northward.

The researchers note that the cooling extends deep below the surface, suggesting reduced ocean heat transport rather than atmospheric effects. “It is changing ocean heat transport,” said Stefan Rahmstorf of Potsdam University. Other experts caution that data are still sparse and that the findings add to, rather than settle, the debate.

If the AMOC continues to weaken toward a tipping point, scientists warn of serious climate consequences: accelerated sea‑level rise along the US East Coast, harsher winters in Europe, and disrupted African monsoon patterns that could trigger prolonged droughts.