Photo by Dimitry B

The collapse of a critical Atlantic Ocean current system can no longer be considered a low-probability event, according to new research that challenges previous climate projections and adds urgency to cutting fossil fuel emissions.

The AMOC under threat

The Atlantic Meridional Overturning Circulation (AMOC) – the vast current system including the Gulf Stream – acts as Earth’s climate regulator, carrying warm tropical water to Europe and the Arctic. Scientists already knew the AMOC was at its weakest point in 1,600 years due to climate change, but previous models suggested collapse before 2100 was unlikely.

Extended models reveal new risks

The breakthrough study, published in Environmental Research Letters, extended climate projections to 2300-2500 instead of stopping at 2100. The results were stark: under high-emission scenarios, 70% of model runs led to AMOC collapse. Even with intermediate emissions, 37% showed collapse, and 25% of low-emission scenarios still resulted in shutdown.

Critically, while the tipping point could be crossed within decades, the actual collapse might not occur until 50-100 years later – explaining why shorter-term models missed this risk.

Irreversible consequences

AMOC collapse represents a fundamental shift between stable states, not a gradual change. Once triggered, reversal would require millennia. The mechanism involves collapsing deep ocean mixing as global heating reduces winter cooling, weakening the circulation that drives the current system.

The global consequences would be catastrophic:

• Western Europe facing extreme winters and summer droughts, with temperatures dropping 3°C per decade
• Tropical rainfall belts shifting, threatening food security for millions
• Additional 50cm of sea level rise along the American Atlantic coast
• Massive disruption to marine ecosystems and reduced ocean CO2 absorption

Scientific consensus shifting

The findings mark a significant shift from previous IPCC assessments. Forty-four leading climate scientists recently warned that collapse risks have been “greatly underestimated,” with observational data already showing concerning trends in North Atlantic deep waters.

“Even in some intermediate and low-emission scenarios, the AMOC slows drastically by 2100 and completely shuts off thereafter,” said Professor Sybren Drijfhout of the Royal Netherlands Meteorological Institute. “That shows the shutdown risk is more serious than many people realise.”

The research underscores that while the tipping point for inevitable shutdown could be crossed within decades under current trajectories, rapid decarbonisation could still prevent this outcome. With AMOC collapse representing one of the most severe climate tipping points, the window for action is rapidly closing.