One part of the warming planet is still cooling
Over roughly the last 150 years, Earth’s surface has warmed almost everywhere. One notable exception sits in the north Atlantic, south-east of Greenland, where a patch of ocean has cooled by as much as 1 degree Celsius. Known as the “cold blob” or “warming hole,” it has become one of the most discussed anomalies in climate science.
According to the supplied source text, the latest evidence points toward a weakening Atlantic Meridional Overturning Circulation, or AMOC, as the most plausible explanation. That conclusion matters because AMOC is a major system of currents that carries warmth from the tropics toward Europe.
Why AMOC is under scrutiny
The AMOC works by moving warm, salty water northward through the Atlantic. As that water cools and becomes denser, it sinks and returns southward at depth. Scientists have long worried that fresh water from melting Greenland ice could disrupt that process by making surface waters less salty and less likely to sink, weakening the circulation.
A weaker AMOC would not be a minor regional change. It could affect European climate and alter rainfall systems, including monsoons that support agriculture in Africa and Asia. That is why any sign of sustained slowdown attracts intense interest.
The challenge is evidence. Direct observations of AMOC strength span only 22 years, which the source notes is not long enough to cleanly establish a long-term trend by itself.
The debate over the cold blob
The “cold blob” has become a proxy battleground for that broader uncertainty. Climate modeling has suggested that if AMOC slows, less warm water reaches the north Atlantic, helping create the cool patch. But that has not been the only explanation on the table.
Other work has argued that the atmosphere may be doing more of the job. One 2022 study highlighted in the source found that rapid Arctic warming reduced the temperature contrast between the pole and the tropics, shifting the jet stream northward into the region. Stronger westerly winds could then increase evaporation, churn the surface ocean, and draw heat out of the water. Added cloud cover could further reduce incoming solar warmth.
In other words, the question has been whether the anomaly is mainly being driven from the ocean below or the atmosphere above.
Why the new evidence matters
The source says the latest evidence backs the AMOC explanation more strongly. That does not settle every debate about pace, timing, or tipping points. But it does make the cold blob harder to dismiss as a purely atmospheric curiosity.
This is significant because AMOC discussions often suffer from a mismatch between public attention and direct observation. There is deep concern about what a large slowdown or collapse could mean, but limited instrumental history for measuring the system cleanly. That leaves researchers leaning on reanalyses, modeling, and indirect indicators such as the persistent cooling region south-east of Greenland.
The cold blob is therefore more than a map oddity. It is one of the clearest visible clues that something unusual is happening in a part of the climate system that helps regulate heat distribution across the Atlantic basin.
For now, the strongest defensible takeaway from the supplied material is cautious but consequential: a patch of cooling in a warming world increasingly appears to support concerns that the Atlantic’s heat-transport system is weakening.
- The cold blob south-east of Greenland has cooled by as much as 1 degree Celsius
- The latest evidence in the supplied source favors a weakening AMOC explanation
- Direct measurements of AMOC span only 22 years
- Other studies have also examined atmospheric drivers such as jet stream shifts and cloud changes
This article is based on reporting by New Scientist. Read the original article.
Originally published on newscientist.com