Refreezing of meltwater is widespread beneath the Greenland Ice Sheet and influences ice flow behaviour, according to a study published online in Nature Geoscience.

Robin Bell and colleagues analysed geophysical data and identified distinctive ice units at the base of the Greenland Ice Sheet that are consistent with refrozen meltwater. The units can exceed a kilometre in thickness, extend for tens of kilometres across northern Greenland, and have induced warping and deformation of the surrounding ice sheet. Interestingly, the authors find that the fastest-flowing regions beneath the Petermann Glacier in northern Greenland, which is rapidly losing mass to the Arctic Ocean as the climate warms, coincide with these basal ice units.

Bell and colleagues suggest that the heat released by the refreezing of meltwater softens the surrounding ice sheet and leads to enhanced flow.

In an accompanying News and Views article, Joseph MacGregor writes that the researchers “have established that significant basal refreezing is related to both surface melting and faster ice flow in Greenland.”