Sea level rise threat from submarine melting of glaciers

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. For the Greenland Ice Sheet (GrIS), this mass flux to the ocean includes: surface melt, leaving the ice sheets as runoff and subglacial discharge; subsurface melt of glaciers; and calving (and eventually melt) of icebergs. At present, GrIS 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.

Submarine melting of glaciers are affected both by the fjord stratification and subglacial discharge. In particular, the latter generates buoyancy driven plumes rising vertically and mixing with the submarine meltwater and the entrained ambient waters. 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 entrainment of ambient waters and consequently submarine melting.