Shrinking Arctic sea ice could cause more-vigorous mixing of ocean heat in northern waters, eventually leading to further melting.

Tom Rippeth of Bangor University, UK, and his colleagues measured water temperatures at different depths and locations across the Arctic Ocean. They found that heat rose more quickly from warm, deep layers of water that ran into rough patches on the sea floor than from areas that have a more even floor.

Such mixing might become more common in a warming world, the authors say. As sea ice disappears, the atmosphere can transfer more of its energy into the ocean, which drives ocean mixing. The rising heat from this mixing could cause sea ice to decline even more.

Nature Geosci. http://dx.doi.org/10.1038/ngeo2350 (2015)