Is a warming of the Antarctic continental shelf reversible?

• Main Authors: Hellmer, Hartmut, Kauker, Frank, Timmermann, Ralph
• Format: Conference Object
• Language: unknown
• Published: 2015
• Subjects: Antarctic; The Antarctic; Weddell Sea; Weddell; Ronne Ice Shelf; Antarc*; Filchner Ronne Ice Shelf; Filchner-Ronne Ice Shelf; Ice Sheet; Ice Shelf; Ice Shelves; Iceberg*
• Online Access: https://epic.awi.de/id/eprint/38748/; https://hdl.handle.net/10013/epic.46039

Antarctic ice sheet mass loss and thus part of global sea-level rise is related to enhanced ice stream discharge to the fringing ice shelves. The transfer of ice into the ocean occurs via iceberg calving and ice shelf basal melting. For decades the balance of both terms was assumed to be in favor of the calving, but recent results, based on remote sensing, revealed that basal melting seems to be at least of similar importance. A recent model study indicates that future atmospheric conditions in the southern Weddell Sea may switch the continental shelf, formerly dominated by the formation of cold saline waters, to one influenced by warm open ocean waters with consequences for the basal mass flux and ice shelf/ice sheet dynamics. Here, we continue the simulations showing a warming of the Filchner-Ronne Ice Shelf cavity, applying 20th-century atmospheric and basal mass flux forcing at different future points in time. Our numerical study indicates that once the system reaches the 'warm phase', a positive meltwater feedback stabilizes the shelf circulation such that only a reduction to 20th century basal mass flux can stop warm water from penetrating onto the continental shelf and into the sub-ice cavity. This has implications for the future of the Antarctic Ice Sheet, since a major decrease of basal melting only can be achieved by a significant disintegration of the floating portion of the ice sheet.