A climate nightmare lurks in the Atlantic. Europe is starting to pay attention.

From Reykjavík to The Hague, European governments are starting to prepare for a literal sea change that would end life as we know it on the continent. In the depths of the North Atlantic, a vast system of swirling currents known as the Atlantic Meridional Overturning Circulation, or AMOC, carries warm tropical waters north, preventing Europe from freezing. But as humans continue pumping planet-warming gases into the atmosphere, this oceanic heat pump will weaken. It might even fizzle out. A colder-than-usual patch of water just south of Greenland, nicknamed the “cold blob,” has some scientists worried this slowdown is already well underway.