A vast patch of ocean south of Greenland has continued to puzzle climate scientists by cooling even as much of the planet experiences record-breaking temperatures, prompting renewed concern over the future of a critical Atlantic Ocean current system and its potential consequences for weather patterns worldwide.
The unusual region, often referred to as the “North Atlantic warming hole” or the “cold blob,” stands out on global temperature maps as one of the few areas showing a long-term cooling trend. Located in the subpolar North Atlantic between Greenland and Europe, the patch has cooled steadily over the past century despite the broader warming of the world’s oceans linked to climate change.
Recent scientific studies suggest that the phenomenon is closely connected to the weakening of the Atlantic Meridional Overturning Circulation (AMOC), a vast network of ocean currents that transports warm water from the tropics towards northern Europe and returns colder, denser water southward through the deep ocean. Researchers say the cold patch may be one of the clearest visible indicators that this crucial ocean “conveyor belt” is slowing down.
Scientists have tracked temperature variations in the region for decades, but early observations were often dismissed as anomalies. However, long-term analyses of historical sea-surface temperature records have shown that while average global temperatures rose significantly during the last century, this section of the Atlantic experienced a noticeable cooling trend.
The AMOC plays a vital role in regulating global climate by redistributing heat across the planet. Warm surface waters carried northward eventually cool, become denser and sink, creating a circulation cycle that helps maintain relatively mild winters in parts of Europe. The system also supports marine ecosystems and assists in storing carbon deep within the ocean.
Researchers argue that a slowdown in the AMOC reduces the amount of heat transported into the North Atlantic, resulting in the formation of the cold blob. Multiple studies conducted over the past decade have strengthened this theory. Recent analyses using observational data and climate models found that a weakened AMOC remains the most convincing explanation for the persistent cooling pattern.
Scientists warn that continued weakening of the circulation system could have far-reaching consequences. Climate models indicate that a major slowdown or eventual collapse of the AMOC would alter rainfall patterns, intensify weather extremes and disrupt ecosystems across several continents.
The impacts could be particularly significant for Europe, where temperatures may fall sharply in some regions despite global warming. Changes in atmospheric circulation could also shift tropical rainfall belts and affect weather systems far beyond the Atlantic basin.
Experts say South Asia could face serious consequences as well. A weaker AMOC could influence Pacific Ocean temperatures and strengthen El Niño events, which are often associated with weaker monsoons in India. Since a large share of Indian agriculture depends on seasonal monsoon rainfall, any disruption could affect crop production, water availability and the livelihoods of millions of farmers.
In addition to weather-related impacts, scientists caution that a weakening AMOC may reduce the ocean’s ability to absorb carbon dioxide from the atmosphere, potentially accelerating global warming. Some studies have also suggested that changes in ocean circulation could contribute to faster melting of Antarctic ice sheets and rising sea levels.
While researchers emphasise that a complete collapse of the AMOC is not considered imminent, growing evidence that the system is weakening has intensified calls for urgent action to reduce greenhouse gas emissions. Scientists say the cold patch south of Greenland serves as a stark reminder that climate change can produce unexpected and far-reaching effects, even in regions that appear to be cooling rather than warming.
