A new study suggests that the Atlantic Meridional Overturning Circulation, or AMOC, could already be on an irreversible path toward collapse. Researchers estimate a 10 to 23 percent chance that the tipping point has been crossed, even if emissions are cut aggressively today. The findings, published by scientists at the Open University and the University of Exeter, add urgency to global climate action.
What is the AMOC and why does it matter?
The AMOC is a massive system of ocean currents that carries warm, salty water from the tropics toward the North Atlantic. As this water cools, it sinks and flows back south, helping regulate temperatures across Europe, Africa, and the Americas. Without it, Europe could experience near-Arctic conditions, and monsoon patterns worldwide could weaken. The system is already showing signs of strain. Melting Greenland ice sheet, driven by climate change, is adding freshwater to the North Atlantic. That freshwater makes the ocean less dense, slowing the sinking process that drives the circulation. Scientists have warned for years that a full shutdown could trigger abrupt, far reaching climate shifts.
The new study: a sobering look at committed collapse
To assess the risk, Phil Holden, Tim Lenton, and their team ran 21 computer simulations. Each simulation varied when greenhouse gas emissions would peak, from 2005 through 2135, and included different rates of Greenland ice melt. The models assumed emissions would fall to net zero over 35 years after the peak, with Greenland ice melt held constant. Each run covered 300 years. Under the most conservative scenario, with emissions peaking in 2025 and Greenland ice adding only 54 millimeters to sea level rise by 2100, the model found a 10 percent chance that AMOC collapse is already locked in. If net zero is delayed until 2100, that probability jumps to 80 percent. With a less conservative ice melt projection of 274 millimeters of sea level rise by 2100, the chance of being committed rises to 23 percent.
The researchers defined committed collapse as the point when the circulation no longer transports heat to high latitudes, effectively shutting down the overturning current. Even after that point, the actual collapse takes time. The average delay between commitment and the collapse event is 84 years in the simulations, with the earliest possible collapse occurring around 2060. The model used relatively low resolution, with 5 degree grids, compared to the 1 degree grids used in many state of the art climate models. But Lenton said the low resolution was a deliberate choice to run many long simulations. He noted that recent work with higher resolution models suggests the risk estimates might actually be higher, not lower.
What can we do?
Taken together, these findings suggest that the window to prevent AMOC collapse is narrow but not yet closed. The model shows that delaying net zero by just 10 years beyond the point of commitment accelerates the collapse timeline from 84 years to 57 years on average. That reinforces the need for rapid emissions cuts. Tim Lenton says the model is telling us to do everything in our power to get to net zero as quickly as possible, to keep the probability at the lower end of the scale. Other scientists urge caution. Jonathan Baker at the Met Office says the low resolution model may not capture all the sensitivity of the AMOC, and further work with multiple climate models is needed before drawing reliable conclusions. Still, the study provides a new way to frame the risk: not just when collapse might happen, but whether we are already committed to it.
Climate models like the one used in this study are increasingly powered by machine learning techniques that can simulate complex systems more efficiently. For teams working on emissions scenarios, these AI driven tools help identify the most likely paths forward. If you are exploring how artificial intelligence can assist in climate modeling or other fields, check out our guide to the best AI tools in 2026 to see what is on the horizon.
