The AMOC is a complex tangle of currents that works like a giant global conveyor belt. It transports warm water from the tropics toward the North Atlantic, where the water cools, becomes saltier and sinks deep into the ocean, before spreading southwards. It plays a crucial role in the climate system, helping regulate global weather patterns. Its collapse would have enormous implications, including much more extreme winters and sea level rises affecting parts of Europe and the US, and a shifting of the monsoon in the tropics.