February 27, 20253 min readCrucial Ocean-Current System Is Safe from Climate Collapse―for NowThe Atlantic Meridional Overturning Circulation likely won't completely collapse with global warming, but any weakening could have grave consequences worldwideBy Humberto Basilio & Nature magazine There have long been worries that a critical network of currents in the Atlantic Ocean could come to a halt catastrophically as the climate changes. Wirestock/Getty ImagesA crucial ocean-current system seems unlikely to collapse even in the face of severe climate change ― despite predictions that it would disintegrate if Earth continues to warm. Thats the finding of a study suggesting that the Atlantic Meridional Overturning Circulation (AMOC) will survive at least until the end of the century.The study found that the combined forces of various ocean currents and winds would keep the system stable even under the most pessimistic climate scenarios.The authors are confident that there is sufficient evidence to support this finding, even though the climate models they analysed do not perfectly mirror reality. Unlikely isnt impossible, says Jonathan Baker, a co-author of the study and a climate scientist at the Met Office in Exeter, UK. But we have confidence in our results. The work is published today in Nature.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Water-moving machineThe AMOC is like a giant conveyor belt in the Atlantic Ocean: warm water travels in the upper layers from south to north. Once the water reaches its northernmost point, it sinks and travels southwards in a cold, deep layer until it reaches the southern oceans, where it rises back up to the surface. The AMOC therefore has a crucial role in the global distribution of heat, salt and other components of seawater.The intensity of the AMOC has declined over time, a trend traced to polar ice melt, changes in wind patterns and precipitation changes linked to climate change. Although scientists agree that the collapse of the AMOC would have devastating consequences for local and regional climates, they are divided on whether and when such an event would occur.Studies of the AMOCs future generally rely on analyses of its past behaviour and on models that simulate future scenarios under different climate conditions. Some have concluded that the AMOC would reach a tipping point sometime between 2025 and 2095, then abruptly shut down. Other research indicates that a collapse is unlikely before the end of the century, but scientists had not previously identified the factors that might be stopping it from happening.A passel of modelsBaker and his team used 34 climate models to examine how the AMOC might respond to two extreme scenarios: a four-fold increase in carbon-dioxide levels from pre-industrial levels; and the addition of massive amounts of freshwater, consistent with the melting of the Greenland ice sheet. The team found that the AMOC would weaken in both scenarios, but not collapse.Key to the stability, Baker and his team suggest, are powerful winds in the Southern Ocean that help to drive deep water in the region towards the surface. This upwelling has a crucial role in maintaining the AMOC because it balances out the downwelling in the northern Atlantic.Baker and his team also found that the AMOC would collapse if a Pacific Meridional Overturning Circulation developed and increased the amount of downwelling. And although this circulation pattern does develop in all their models, it is too weak to counteract the rising water, Baker says.It's a very impressive and intriguing study, says Ren van Westen, a climate scientist at the Royal Netherlands Meteorological Institute in De Bilt. But he adds that, although Bakers results reaffirm that collapse is unlikely, even a weakening could have harmful consequences. It doesnt mean that we can sit back and relax again, its still a worrying effect, van Westen says.Peter Ditlevsen, a climate physicist at the University of Copenhagen and co-author of the study suggesting that the AMOC would collapse before the end of this century, agrees. Like Baker, he emphasizes that reducing greenhouse-gas emissions is crucial to prevent catastrophe. Time matters, he says. We do not want to hit any tipping point. And this is one of the dangerous ones.This article is reproduced with permission and was first published on February 26, 2025.