Climate change may shut down a current that keeps the North Atlantic warm

By Rachel Becker

Both Europe and North America are warmed in the winter by currents circulating in the Atlantic — but climate change threatens this source of warmth. If the Earth warms too much, it’s possible that this current could collapse entirely, new research says. That would mean frigid winters for countries along the North Atlantic, expansion of the sea ice in the Greenland, Iceland, and Norwegian seas, and a shift in rainfall across the world.

The current is called the Atlantic Meridional Overturning Circulation (AMOC) and it’s like a conveyer belt that brings warm water from the tropics to the the cooler reaches of the North Atlantic. There, the water loses its heat to the atmosphere. Because water gets denser as it gets colder, it sinks. This lower band of cool water circulates back to the tropics where it warms and repeats the process all over again. If you’ve ever watched soup boil up, spread, and then sink, it works kind of like that.

“It is a major player in the climate system, important for Europe and North America. So it’s a big deal,” says Tom Delworth, a scientist with National Oceanic and Atmospheric Administration who was not involved in this recent study. The AMOC is the same current that collapsed and triggered an icy apocalypse in the 2004 movie The Day After Tomorrow (featuring Verge favorite Jake Gyllenhaal). “It wasn’t quite accurate in the science, but that’s okay, it was entertaining,” Delworth says.

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