Wednesday July 1, 2026
Smithsonian Magazine —
A patch of water south of Greenland and Iceland has cooled by nearly 1.8 degrees Fahrenheit since 1900. A new study suggests that it shows a crucial system of ocean currents is weakening, which could alter Earth’s climate.
The ocean has been heating up over the past century, largely due to human activity that produces heat-trapping greenhouse gases. But strangely, a patch of the Atlantic Ocean south of Greenland and Iceland has been trending in the opposite direction.
While this may sound like good news for our warming planet, the “cold blob” could be a sign of a more concerning pattern with far-reaching effects.
In a study published on May 28 in the journal Geophysical Research Letters, a team of scientists used observations dating back to 1870 to analyze the mysterious phenomenon. Their findings suggest that the cold blob may have resulted from broader changes taking place throughout a crucial system of currents in the Atlantic Ocean, which could drastically alter the Earth’s climate.
Worldwide, the sea surface temperatures have risen by an average of about 1.8 degrees Fahrenheit since 1900, but the cold blob has chilled by almost that amount during that period. Some scientists suspect that the cooling patch of water is an isolated event caused by interactions with the local atmosphere. In 2022, a team reported that increased westerly winds were removing heat from the ocean surface there.
Other researchers, however, say that it’s a sign that the Atlantic Meridional Overturning Circulation, or AMOC, is weakening. The AMOC is a system of currents of varying depths that spans the entire Atlantic Ocean. This “global conveyor belt” is responsible for carrying warm water to the North Atlantic and cold water to the south. Past research suggests that the AMOC is slowing due to climate change, and, if it continues, it could cause sea level rise on the U.S. East Coast, cool Europe and disrupt precipitation patterns in parts of South America, Africa and India, among other alterations.