Mysteries of the Deep

Something is stirring in the waters off the coast of Greenland, and it isn’t a submarine fleet sent by Donald Trump.

According to reporting by the New Scientist, evidence is mounting that the Atlantic Meridional Overturning Circulation — a massive system of deep sea currents that acts like a conveyor belt for the world’s oceans known as AMOC — is starting to slow its gears. As it does, cold waters from the Greenland ice sheet are allowed to pool in the North-Atlantic, creating a “cold blob” that’s only getting colder as the rest of the world warms up.

This in turn has a major impact on jet streams, fueling extreme weather across the world. Should it collapse, the New Scientist notes that the AMOC could act as a climate tipping point, setting off a chain reaction resulting in much colder weather for some, and much drier weather for others by as early as 2040.

“The cold blob can disturb the atmospheric jet stream and storm activities, so it has implications for extreme weather events in North America and Europe,”  Laifang Li, assistant professor of meteorology and atmospheric science at Penn State explained in a press release announcing an earlier study on the AMOC.

Identifying how severe this cold blob ends up being may depend on the cause for the weakening AMOC — a topic which has researchers split. Some, like Li, say it’s caused by atmospheric forces, while others have identified oceanic conditions as the culprit.

In the latter camp is Stefan Rahmstorf, researcher at the Potsdam Institute for Climate Impact Research, whose team found evidence that heat loss from the ocean surface has been slowly shrinking since 1955, meaning whatever’s happening is driven by ocean currents. As Rahmstorf plainly told the New Scientist: “even if, in some modelling approaches, it seems possible that the cold blob is caused by the atmosphere, in fact, the data show it is caused by the ocean.”

One thing that’s sure is that the AMOC is definitely weakening, as troubling data from deep-ocean buoys shows crucial ocean currents slow at various points throughout the Atlantic. What this ultimately means remains to be seen — but rest assured, it isn’t good.

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