A “cold blob” in the North Atlantic may reveal weakening ocean currents

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Researchers have linked the unusual Atlantic “cold blob” to reduced ocean heat transport, providing further evidence of changes in a major ocean circulation system.

Arctic sea ice is closely tied to ocean and climate changes in the North Atlantic.

While the global ocean has generally gained heat over recent decades, one region of the subpolar North Atlantic has moved in the opposite direction. The cooling patch south of Greenland and Iceland appears to be driven mainly by weakening ocean heat transport, according to a study published in Geophysical Research Letters.

What cooled the “cold blob”?

The research examines a long-running question about the “cold blob,” also known as the Atlantic “warming hole.” Scientists have debated whether currents are bringing less heat into the region or whether the ocean is releasing more warmth to the atmosphere.

The cold patch in the North Atlantic could be a concerning sign that the crucial Atlantic Meridional Overturning Circulation (AMOC) is slowing down. Credit: NASA Scientific Visualization Studio/Goddard Space Flight Center

The results favor the first explanation. After analyzing observation-based ocean heat content and surface flux