THE WASHINGTON POST: Oceans are warming, but scientists are concerned about this cold blob

As the planet warms, it’s becoming increasingly rare to see cooler than average conditions across vast stretches of the ocean, particularly as an expected super El Niño scorches parts of the Pacific.

But right now, an expansive area of well below-average ocean temperatures exists in the North Atlantic, to the east of Newfoundland. There, unusually cool waters have lingered for the last year.

This patch of cool water is occurring in one of the few areas where the ocean hasn’t warmed in recent decades - and where scientists are closely monitoring for changes in the Atlantic meridional overturning circulation (AMOC).

The AMOC, which extends deep into the Atlantic Ocean, is a vital current that carries heat northward from the tropics toward the pole and plays a critical role in the climate around Greenland, Iceland and northern Europe. If the cold blob persists for years, it could eventually cool the climate in these places - and signal this key current is weakening. Should it collapse, a massive cooling could occur in the Northern Hemisphere, while it warms in the south; sea levels could rise in some areas and seasons could flip in others.

As this conveyer belt of warm, salty water reaches the North Atlantic, it loses heat to the cold air above, becoming denser and sinking into the deep ocean. But as ice in the Arctic melts, introducing more freshwater into the sea, it becomes harder for the water to sink, potentially slowing down the current.

Scientists have been monitoring the current’s behaviour in the Irminger Sea, south of Greenland, where the US National Science Foundation recently announced that it is dismantling its ocean monitoring equipment.

In Iceland, a collapse of the AMOC is considered a national security risk, since it would send winter temperatures plunging to minus-50 degrees Fahrenheit (-10C).

Recently published research from a team led by Stefan Rahmstorf of the Potsdam Institute concluded that “the strong evidence for a weakening AMOC is a serious concern for society and policy” and that it requires “urgent attention.” However, other research published last year found no evidence of long-term weakening, but that it was still expected to slow some in the future.

There’s high confidence that the AMOC is weakening according to the UN Intergovernmental Panel on Climate Change. The IPCC has indicated, with medium confidence, that it will not abruptly collapse before 2100.

But what about the recent cold blob? Does it offer a sign of AMOC’s eventual collapse or can it be explained by a combination of forces?

Over the last week, the current cold blob has trended on social media, raising fresh concerns about the status of AMOC.

While stormy and windy weather in the North Atlantic have enhanced the cold blob this year, those factors don’t immediately describe why it has remained there for a year straight.

Other natural climate patterns, such as the Atlantic Multidecadal Oscillation (AMO), have affected the ocean’s conveyer belt. When the AMO is in its positive phase, waters warm in the North Atlantic. The opposite is generally true when it’s in its negative phase.

From mid-2023 to mid-2025, when the AMO was predominantly in its positive phase, the cold blob disappeared for extended periods. But when it became negative in mid-2026, the cold blob returned.

Based on this, a mix of climate forces - including human-driven warming as well as natural variability - appear to be contributing to the current conditions. And climate models predict that the cold blob could linger for the rest of the year - and possibly expand and become more frigid.

What the current cold blob means for the future state of AMOC is uncertain, but models stop short of signalling widespread cooling across western Europe, Iceland or Greenland - the doomsday scenario that has so far been the stuff of movies.