Ocean – Ice Shelf Interaction

Fig. 1: Schematic representation of the polar ocean interacting with a large Antarctic ice shelf. (Photo: Alfred-Wegener-Institut)

The mass loss of the Antarctic and Greenland Ice Sheets and thus global sea level rise is strongly related to the dynamics of their ice streams. The latter drain ice into the fringing ice shelves and glaciers which, due to a reduced thickness, float on the ocean. Mass loss to the ocean occurs  via iceberg calving at the ice shelf fronts and melting at the base.

Recent results, based on remote sensing, revealed basal melting to be the larger term for the Antarctic Ice Sheet. The basal mass loss is either fueled by cold, highly saline waters, due to the depression of the freezing point, or heat transported from the open ocean into the ice shelf cavities (Fig. 1).

At the deep grounding line (1300 m below sea level) of the relative small Pine Island Ice Shelf, which fringes the Amundsen Sea, this warm water causes the highest Antarctic melt rates of more than one hundred meters per year. In contrast, the big ice shelves like Filchner-Ronne and Ross with a size of up to 450,000 km² are in contact with the cold, saline shelf water, thus facing melt rates significantly less than one meter per year.

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