Small and large scale driving icebergs and glaciers melting*

Rising global temperatures have led to an increase in the discharge of ice from the Antarctic and Greenland ice sheets. For the Greenland Ice Sheet, this mass flux to the ocean includes: surface melt, leaving the ice sheets as runoff and subglacial discharge; subsurface melt; and calving of icebergs. The freshwater discharged from Greenland is transformed by fjord processes before being released into the large-scale ocean. Hence, knowledge of the fjords’ dynamics is fundamental to understand how the input of modified freshwater into the ocean impacts ocean dynamics and climate.

Major gaps in understanding include the interaction of the buoyancy-driven circulation (forced by the glacier) and shelf-driven circulation, and the dynamics in the near-ice zone. The former occurs on scales of hundreds of meters to kilometers, the latter on scales of millimeters to meters. The links between small and large scales processes that influence the climate system, via the melting of icebergs and glaciers and the freshwater discharge in the ocean, must be understood before appropriate forcing conditions can be supplied to ice sheet and ocean/climate models.