Edge of the Filchner-Ronne Ice Shelf in the Weddell Sea, Photo: Ralph Timmermann, Alfred Wegener Institute

Edge of the Filchner-Ronne Ice Shelf in the Weddell Sea, Photo: Ralph Timmermann, Alfred Wegener Institute

Edge of an ice shelf close to the Halley Station, Antarctica. Photo: Ralph Timmermann, Alfred Wegener Institute

Formation of giant icebergs is a process typical to the floating ice shelves in Antarctica. A new study indicates that an abrupt increase of basal melting may cause a substantial thinning of the large Filchner-Ronne Ice Shelf in the Weddell Sea. Photo: Ralph Timmermann, Alfred Wegener Institute

Formation of giant icebergs is a process typical to the floating ice shelves in Antarctica. A new study indicates that an abrupt increase of basal melting may cause a substantial thinning of the large Filchner-Ronne Ice Shelf in the Weddell Sea. Photo: Ralph Timmermann, Alfred Wegener Institute

Map of the Weddell Sea and the Filchner-Ronne Ice Shelf. Graphic: Alfred Wegener Institute

Simulated evolution of near bottom temperatures in the Weddell Sea. a-d. Values are from 60 m above bottom for the period 2030-2099 of the HadCM3-B/A1B scenario. Warm pulses into the Filchner Trough (2037) are followed by a return of the shelf water masses to the cold state typical for present conditions. The final (unrevoked) destruction of the slope front starts in 2066; by 2075, the tongue of slightly modified warm deep water reaches the Filchner Ice Shelf front. It fills the deeper part of the Filchner Ice Shelf cavity and enters the Ronne Ice Shelf cavity near the grounding line south of Berkner Island in 2081. By 2095, warm water fills most of the bottom layer of the Filchner-Ronne Ice Shelf cavity, reaching a quasi-steady state.

Illustration of the present conditions of the circulation in the Southern Weddell Sea: A consolidated sea-ice cover forms high-salinity shelf water (blue arrow) that prevents the warm coastal current (red arrow) from passing the coastal shelf and moving into the shelf ice cavitiy. Graphic: Alfred Wegener Institute

Illustration of simulated conditions for the year 2070: Due to thinning of the sea-ice cover less high-salinity shelf water is formed. This amount of shelf water is too small to prevent the warm coastal current from passing the continental slope. It fills the deeper part of the Filchner Ice Shelf cavitiy, bringing lot of warmth to the bottom side and the grounding line of the ice shelf, which starts to melt from below. Graphic: Alfred Wegener Institute