Atlantic meridional overturning circulation is weakening – what does it mean for Europe?

The latest study conducted by scientists from the USA, Canada and the United Kingdom confirms earlier assumptions: the Atlantic Meridional Overturning Circulation (AMOC) has clearly weakened over the past two decades. Contrary to appearances, this is not merely a hydrological curiosity, but a worrying fact.

Ocean currents are weakening

The results of the study published in April this year in the journal Science Advances are not groundbreaking in terms of the thesis. The possible weakening of AMOC has been discussed for over a dozen years, but previous theories were based primarily on computer models. Empirical evidence has so far been lacking.

Thanks to an international initiative undertaken by researchers from the University of Miami, the National Oceanography Centre in Southampton, and the Bedford Institute of Oceanography in Canada, the phenomenon has been documented in a way that leaves no doubt. Scientists used observational data from four mooring arrays located along the western boundary of the North Atlantic (from 16.5°N to 42.5°N) for their analysis.

A comparison of readings from pressure gauges placed at depths of more than 1,000 m confirmed that over the past 20 years there has been a significant decline in deep water transport in the western circulation zone. AMOC is likely approaching a tipping point at which it may ultimately stop, says oceanographer Shane Elipot, one of the authors of the publication.

What is the Atlantic meridional overturning circulation?

Why should we care about what is happening in the ocean, a kilometer below the surface? It turns out that the Atlantic Meridional Overturning Circulation (AMOC) is one of the key factors influencing the Earth’s climate and living conditions in the oceans. Its further weakening or complete collapse could have catastrophic consequences for the entire planet.

AMOC is a system of ocean currents that flow from the surface toward the ocean floor and are responsible for transporting vast amounts of water: warm water northward and cold water southward. Thanks to this slow but constant mixing of Atlantic waters, heat and nutrients are transported, which determine the survival of marine organisms.

What drives this gigantic mechanism? According to scientists from the National Oceanic and Atmospheric Administration (NOAA), the course of the overturning circulation is driven by changes in salinity and water temperature. When warm surface water begins to freeze near the poles, sea ice forms and the concentration of salt in the ocean increases. Cold, dense and salty water sinks toward the bottom and moves southward.

The entire cycle, which for a given cubic meter of water can last up to a thousand years, ends with so-called upwelling, i.e. the rising of cold water to the surface and its gradual warming.

What does it mean for Europe?

From the results of a study by French scientists, also published in April this year, it can be learned that by the end of the 21st century the Meridional Overturning Circulation may weaken by as much as 42–58 percent. The slowdown of AMOC is primarily caused by global warming – higher temperatures in the Arctic region limit the process of sea ice formation and hinder the life-sustaining transport of cold water.

The weakening of the Meridional Overturning Circulation is most likely to lead to a significant cooling of the climate in Europe, whose coasts are currently warmed by the transport of tropical water. The most pessimistic scenarios predict the onset of exceptionally cold and snowy winters as well as extremely dry summer months. To make matters worse, further disruption of the ocean current system may raise sea levels – by up to 50 cm in western Europe, posing a risk of coastal flooding.

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Sources:

Qianjiang Xing et al. Meridionally consistent decline in the observed western boundary contribution to the Atlantic Meridional Overturning Circulation.Sci.Adv.12, eadz7738(2026).DOI:10.1126/sciadv.adz7738

Valentin Portmann et al., Observational constraints project a ~50% AMOC weakening by the end of this century.Sci. Adv.12,eadx4298(2026).DOI:10.1126/sciadv.adx4298

https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/climate/ocean-and-cryosphere-report/srocc_amoc.pdf

https://oceanservice.noaa.gov/facts/amoc.html

https://www.theguardian.com/environment/2026/apr/15/critical-atlantic-current-significantly-more-likely-to-collapse-than-thought