Eurasian Arctic Ice Shelves and Tidewater Ice Margins

Abstract

Despite the presence of about 4000 km of marine-terminating glaciers and ice caps in the Eurasian Arctic, there are few floating ice shelves. Neither are there extensive areas of multi-year shorefast sea ice which might thicken into composite ice shelves themselves. The archipelagos of Severnaya Zemlya and Franz Josef Land contain some ice shelves in addition to grounded tidewater ice fronts. The largest Eurasian Arctic ice shelf was the Matusevich Ice Shelf, Severnaya Zemlya, at about 240 km2 with a drainage basin of about 1100 km2; this ice shelf largely broke up in 2012. In Franz Josef Land, a number of ice caps have smooth and very low surface gradient seaward margins, covering over 300 km2 or 2% of the total area of the ice caps in the archipelago. These low-gradient areas are located mainly in relatively protected embayments and produce large tabular icebergs of up to several kilometres in length. Whether individual areas are floating in hydrostatic equilibrium or are simply close to buoyancy, they provide the major modern source of tabular icebergs to the Barents Sea. Svalbard has about 860 km of coastal ice cliffs, but almost none of the ice margin appears to be afloat. There may be short periods, during the active phase of the surge cycle, where marine margins become afloat. Neither is there evidence that the margins of the marine-terminating glaciers on Novaya Zemlya are floating. Twenty-five to fifty percent of the bed of the three largest ice caps in the Eurasian Arctic lies below sea level. Thus, in a warming Arctic, the ice margin would eventually retreat onto land, curtailing mass loss by iceberg production and providing a break on rapid ice-cap disintegration through calving.