Scientists Find Clues to Atlantic Current’s Future in Ancient Iceberg Debris
By Elise Cutts, Eos/AGU.
Excerpt: New research shows that present-day iceberg loss from Greenland stacks up to some of the most dramatic iceberg-slinging episodes in recent geological history. Such events involved the disintegration of an ice sheet over North America and coincided with the weakening or failure of vital ocean currents in the North Atlantic—as well as severe climate swings. Despite this concerning parallel, there’s reason to think that modern iceberg loss from Greenland won’t disrupt ocean circulation within the next few decades, according to authors of the study, published in Science. ...The Atlantic Meridional Overturning Circulation, or AMOC, flows northward along the east coast of North America before veering east toward Scandinavia. Along the way, evaporation leaves behind water that’s increasingly cool and salty and therefore dense. In the Arctic, this dense, cold water sinks to join deepwater currents headed south to the Antarctic. Shutting down the AMOC would wreak climate chaos. ...The AMOC has shut down multiple times, most recently during a period called the Younger Dryas that began some 13,000 years ago. This cold snap came right at the tail end of the last glacial period. For 1,300 years, it returned the defrosting world to a climate echoing that of the Last Glacial Maximum. ...“If a sufficient amount of fresh water is added to the northern Atlantic, the AMOC could collapse,” said climate physicist Peter Ditlevsen of the University of Copenhagen. “The big research question for the present climate situation is, How much fresh water is needed for a shutdown?”....