Scientists have feared AMOC’s decline for some time. Previous studies have shown it to be at its weakest point in 1,600 years. But research published this month suggests that a collapse may come much sooner than anticipated.
One study, published Thursday in the journal Science Advances, used climate models and current data to predict the decline in the coming decades.
Researchers found that the system is on course to slow by more than 50% by the end of the century and could pass a significant tipping point by mid-century, at which point its decline would become irreversible.
“We found that the AMOC is declining faster than predicted by the average of all climate models,” said lead researcher Valentin Portmann, of the Inria Research Center of Bordeaux South-West. “This means we are closer to a tipping point than previously thought.”
A major driver of its slowdown has been the rapid melting of Greenland’s freshwater ice sheet into the Atlantic, which has diluted denser saltwater, making it harder to transfer northward.
He explained: “The more rapidly Greenland melts, the more freshwater floods the North Atlantic. This disrupts the sinking process, effectively applying the brakes to the entire system.”
This research followed another study published last week by scientists at the University of Miami, which found that AMOC has been weakening at four latitudes in the Atlantic.
Professor Stefan Rahmstorf, a leading AMOC researcher at the Potsdam Institute for Climate Impact Research, who was not involved in either study, called it “an important and deeply concerning result” that “confirms that the ‘pessimistic’ climate models—those projecting a severe weakening of the AMOC by 2100—are the most accurate.”
“The most dramatic and drastic climate changes we see in the last 100,000 years of Earth history have been when the AMOC switched to a different state,” Rahmstorf explained.
A shutdown of the current system poses what Canadian climate activist and marine conservationist Paul Watson described as a “domino effect of climatic upheavals.”
Scientists have projected that temperatures in northern Europe could plummet dramatically, with winters in London sometimes reaching below -20°C (-4°F) and those in Norway reaching -48°C (-54°F). It also threatens to dramatically shorten growing seasons, putting food security in peril for hundreds of millions of people.
Tropical storms in the North Atlantic would also become more severe. As the current slows, sea levels are expected to rise, and the greater temperature difference between cooling Europe and the warming tropics can fuel more intense hurricanes and increase the risk of flooding in major coastal cities.
“We must avoid this collapse at all costs,” Rahmstorf said. “The stakes are too high; this isn’t just about Europe’s climate, but the stability of the entire planet.”
Such a dramatic change in the flow of global heat could scramble temperature and rainfall patterns worldwide, putting some areas at greater risk of drought and disrupting the monsoon season that fuels agriculture in many regions.
It also risks becoming self-perpetuating, as the large amounts of carbon released from the ocean could further accelerate AMOC’s collapse. Research published last week found that carbon emissions from the Southern Ocean alone could increase global temperature by about 0.2°C.
“The science is clear: The AMOC is teetering on the edge of collapse, and the window to act is closing,” Watson said. “Yet global leaders remain paralyzed by short-term politics and denial.”
The conclusion of the most recent United Nations climate summit, COP30, has been described as woefully insufficient to address the mounting climate emergency. The roadmap for action released by the host nation, Brazil, excluded any mention of the phrase “fossil fuels” after the conference was overrun by industry lobbyists.
“The time for half-measures is over,” Watson said. “The choices we make in the next decade will determine whether future generations inherit a manageable climate or a world plunged into chaos.”
