Meltwater flowing beneath Greenland's glaciers refreezes into large ice units that could be distorting and even warming the overlying ice layers.

Robin Bell of Columbia University's Lamont-Doherty Earth Observatory in Palisades, New York, and her team used radar data to identify subglacial ice units across northern Greenland. The authors found significant warping of the surrounding layers, which they attribute to the refreezing meltwater below.

Moreover, these ice units were found in areas of fast glacier flow. The authors suggest that energy released from the meltwater as it refreezes is warming the ice above, and thus speeding up the glacier's march towards the ocean.

Nature Geosci. http://doi.org/s7j (2014)