🌡️ The mystery of the Atlantic cold anomaly finds a concerning explanation

In the heart of the gradually warming Atlantic Ocean, a cold zone persists south of Greenland. This thermal anomaly contradicts general trends and raises fundamental questions about the climate mechanisms at work.

Researchers from the University of California, Riverside conducted an in-depth analysis combining a century of ocean data with nearly one hundred different climate models. Their work reveals that only a weakening of the Atlantic Meridional Overturning Circulation (AMOC) system can explain the observed characteristics. This system, often compared to a giant conveyor belt, normally transports warm, salty waters northward before returning colder waters southward, thus playing an essential role in climate regulation.


The method used by the scientists proved particularly enlightening. In the absence of direct measurements of the circulation system over a long period, they used temperature and salinity records as reliable indicators. This indirect approach made it possible to reconstruct the system's evolution over more than one hundred years, offering a valuable historical perspective. Climate models that did not account for this weakening proved incapable of reproducing actual observations.

The consequences of this slowdown extend far beyond the simple local thermal anomaly. The Atlantic circulation system directly influences weather patterns in Europe, altering precipitation and shifting atmospheric currents that guide weather systems. These changes can affect temperatures and climate conditions over a vast geographical area, potentially impacting millions of people.

This research also resolves an important scientific debate concerning the causes of the observed cooling. Some recent models attributed this phenomenon mainly to atmospheric factors such as aerosol pollution, but these simulations did not match observations. The study clearly demonstrates that only the weakening of the circulation system correctly explains the collected data, which calls into question the accuracy of some current climate models.

The technique developed by the researchers opens new perspectives for climate forecasting. By enabling the reconstruction of the system's past evolution from indirect data, it provides a valuable tool for anticipating future changes. Scientists emphasize that this approach could prove crucial for understanding how the climate system will evolve if greenhouse gas emissions continue to increase.

Marine ecosystems represent another important area of impact. Changes in temperature and salinity directly influence the distribution of marine species, potentially leading to population shifts and habitat transformations. These ecological changes could have repercussions on fisheries and marine biodiversity throughout the North Atlantic region.

The Atlantic Meridional Overturning Circulation (AMOC) system

The Atlantic Meridional Overturning Circulation (AMOC) system functions as a massive oceanic conveyor that redistributes heat across the North Atlantic. It transports warm, salty waters from tropical regions to northern latitudes, where they release their heat into the atmosphere before becoming denser and sinking into the depths. This natural mechanism helps maintain relatively mild temperatures in Western Europe.

When this system slows down, less warm water reaches the north, altering established thermal balances. The process of cold water sinking also weakens, disrupting the entire cycle. This slowdown can be explained by several factors, including the increased input of fresh water from the melting of Greenlandic and Arctic ice.

Scientists closely monitor this system because its variations can trigger rapid climate changes. Historically, significant modifications of this circulation have been associated with abrupt climate transitions. Understanding its current functioning helps anticipate how the climate might evolve in the coming decades.

Recent research shows that this system has gradually weakened over the past century. This trend could accelerate with ongoing global warming, which would have significant consequences on weather patterns and ecosystems in the Northern Hemisphere.