Submarine melting of glaciers and its effect on climate*

Rising global air and ocean temperatures have been identified as drivers of the observed increase in the discharge of ice from the Antarctic and Greenland ice sheets. At present the Greenland Ice Sheet mass loss accounts for one quarter of the observed global sea level rise (7.5 ± 1.8 mm from 1992 to 2011) and it is crucial to understand the mechanisms and drivers of this loss to improve our ability to predict future sea-level rise and prepare global societies for its consequences.

Greenland’s glacial fjords constitute a key link between the ocean and the ice sheet. Understanding their dynamics, particularly submarine melting at the glaciers’ edges and the export of freshwater, is important for understanding Greenland’s current transformations, their impact on the climate system and predicting future changes, both to the Greenland Ice Sheet and the climate.

Submarine melting of glaciers, and the associated flux of meltwater, are affected both by the fjord stratification and the discharge of surface runoff at the base of a glacier, i.e. subglacial discharge. The distribution of the subglacial discharge, i.e. single or multiple plumes and/or line vs. point source plumes, has been observed to influence the magnitude and distribution of submarine melting of glaciers. Furthermore, plumes’ sediment loads influence the turbulent heat transport and consequently submarine melting.