An ocean current that is effectively the engine that drives weather patterns is in danger, a new study suggests. The Atlantic Meridional Overturning Circulation is a current that moves surface water north from the tropics, warming seawater and adding salt, bringing warm water to the East Coast and Europe, then sinking and bringing cool water back to the tropics under the surface. It’s been reliable and predictable, probably since the last Ice Age. Scientists, however, say it is now destabilizing. David Thornalley, a paleoceanographer at University College London, has shown that the AMOC is at its weakest point in 1,600 years, the Guardian reports. Without it, what we think of as normal seasons could go away. Researchers published an analysis of more than a hundred years of ocean data in the journal Nature Climate Change Thursday.
That analysis shows major changes in markers that indicate ocean movement and salinity. If the current is weakening, it could mean freakishly cold winters in Europe and parts of the US, plus rising sea levels on the East coast, the Washington Post reports. That could mean catastrophic weather and disruptions of agriculture. Niklas Boers of the Potsdam Institute for Climate Impact Research in Germany wrote the analysis. “The signs of destabilization being visible already is something that I wouldn’t have expected and that I find scary,” Boers said. Events such as the melting of Greenland’s ice sheets, are speeding the change and slowing the current. Levke Caesar, also a member of the Potsam Institute, said, “We might be closer to an AMOC tipping than we think.” (Read more climate change stories.)