Arctic ice sets speed limit for major ocean current
The Beaufort Gyre is an enormous, 600-mile-wide pool of swirling cold, fresh water in the Arctic Ocean, just north of Alaska and Canada. In the winter, this current is covered by a thick cap of ice. Each summer, as the ice melts away, the exposed gyre gathers up sea ice and river runoff, and draws it down to create a huge reservoir of frigid fresh water, equal to the volume of all the Great Lakes combined. Scientists at MIT have now identified a key mechanism, which they call the “ice-ocean governor,” that controls how fast the Beaufort Gyre spins and how much fresh water it stores. In a paper published today in Geophysical Research Letters, the researchers report that the Arctic’s ice cover essentially sets a speed limit on the gyre’s spin. In the past two decades, as temperatures have risen globally, the Arctic’s summer ice has progressively shrunk in size. The...