Although air temperatures are often to blame for the melting of sea ice at the North Pole, scientists have been looking for another culprit, this time from below.

Like a hot plate warming up a refrigerated meal, warm water circulating at 200-800 meters in the Atlantic flows underneath the surface layer of ice in the Arctic, toasting its underside. Normally, Arctic ice would be thick enough to create a cool enough buffer to the warm water below. But the underlying layer of warm water has further heated up by almost 2 degrees Fahrenheit in some spots, it’s encroaching on the ice.

Retreating ice sheets in Greenland. Photo: Ludovic Hirlimann on Flickr

Research was published recently in the Journal of Physical Oceanography by Igor Polyakov from the International Arctic Research Center in Fairbanks, Alaska and colleagues. They found that the worst of it seems to be happening in the Eurasian Basin, where 11-13 inches of ice thickness has been lost over the past 50 years because of warming Atlantic water temperatures. They point out that this loss is comparable to that of atmospheric warming, which is responsible for 11 inches.

The result has been nothing short of the breaking apart of the polar ice sheets. In September 2007, an area of polar ocean the size of California and Mexico combined was exposed for the first time in recorded history because of the northward retreat of ice.