Climate scientists caution, however, that even weakened currents would cause profound harm to humanity. Vital Atlantic Ocean currents are unlikely to completely collapse this century, according to a study, but scientists say a severe weakening remains probable and would still have disastrous impacts on billions of people. The Atlantic meridional overturning circulation Amoc is a system of currents that plays a crucial role in the global climate.
The climate crisis is weakening the complex system, but determining if and when it will collapse is difficult. Studies based on ocean measurements indicate that the Amoc is becoming unstable and approaching a tipping point, beyond which a collapse will be unstoppable. They have suggested this would happen this century , but there are only 20 years of direct measurements and data inferred from earlier times bring large uncertainties. Climate models have indicated that a collapse is not likely before , but they might have been unrealistically stable compared with the actual ocean system.
The latest study is important because it uses climate models to reveal the reason that the Amoc is more stable: winds in the Southern Ocean continuing to draw water up to the surface and drive the whole system. The study does not rule out an Amoc collapse after , and other modelling research suggests collapses will occur after that time. He said it was reassuring that an abrupt Amoc crash was improbable, and that the knowledge could help governments plan better for future climate impacts.
Amoc weakening would still bring major climate challenges across the globe however, with more floods and droughts and faster sea level rise, he added. And even a collapse in the next century would cause devastating impacts for climate and society. The Amoc system brings warm, salty water northwards towards the Arctic where it cools, sinks, and flows back southwards.
Global heating, however, is pushing water temperatures up and increasing the melting of the huge Greenland ice cap , which is flooding the area with fresh water. Both factors mean the water is less dense, reducing sinkage and slowing the currents. The Amoc was already known to be at its weakest in 1, years as a result of global heating, and researchers spotted warning signs of a tipping point in A collapse of Amoc would have disastrous consequences around the world, severely disrupting the rains that billions of people depend on for food in India, South America and West Africa.
