Cooperation:

Damian Gore, Duanne White
Macquarie University, Sydney, Australia
Peter Doran
University of Illinois at Chicago, USA
Sergej Verkulich
Arctic and Antarctic Research Institute, St. Petersburg, Russia
Dominic Hodgson
British Antarctic Survey, Cambridge, United Kingdom
Andrew McMinn, John Gibbson
University of Tasmania, Hobart, Australia
Holger Cremer
University Utrecht, The Netherlands
Bernd Wagner
Institute for Baltic Sea Research, Warnemünde, Germany
Hans-W. Hubberten, Bernhard Diekmann
Alfred Wegener Institute, Potsdam, Germany

Funding: German Research Foundation (DFG)

Antarctica, covered by 97 % with continental ice masses and being surrounded by a wide and variable sea-ice belt, is known to be a key area for global climate change. Variations in the volume of the continental ice masses have direct impact on global sea level. The extensions of the ice sheet and sea ice influence oceanic and atmospheric circulation and, due to the high albedo, global heat balance. Despite extensive international research during the past decades, it is still insufficiently understood how the Antarctic Ice Sheet will react on future climate change.

Investigations

In order to achieve a better understanding of the ice sheet dynamics complex reconstructions of the natural climatic and environmental changes that have occurred in presently ice-free coastal areas (oases) along the ice margin during late Quaternary times are conducted since the early 90th in collaboration particularly with Russian, Australian and USAmerican scientists (see Figure and Table). Amongst the natural archives of past climatic and environmental settings predominantly sediment records at the bottom of presently existing lakes and coastal maine basins are studied. These records frequently hold complex information in their heterogenic compositions, were formed continuously, are well preserved, and frequently can accurately be dated.

The sediment cores as yet recovered usually reflect the regional history following the last ice coverage. The coring sites in the oases Schirmacher, Untersee, Bunger, and Amery presumably were last ice covered during the Late Weichselian glacial, which had its maximum about 18.000 years ago. At two locations on the Windmill Islands, Middle Weichelian subaquatic sediments were penetrated beneath Late Weichselian moraines. Only the sampling sites in the Dry Valleys, which currently are investigated within the scope of a project funded by the German Research Foundation (DFG, grant no. ME 1169/11), have remained unglaciated during the Late Weichselian. These cores, therefore, offer the unique opportunity to study the climatic and environmental history without interruption over an entire glacial-interglacial cycle.

The results as yet existing evidence that the Holocene climate history along the Antarctic ice margin has experienced large regional differenes, contingent upon the specific geographical characteristics. The climate development in individual oases often can be correlated neither with the developments in other oases nor with the development on the central ice sheet. In a similar manner the glaciation history shows distinct regional differences. Migrations of the ice edges are not exclusively triggered by variations in melt rates in dependence on temperature changes. Of importance for the mass balance is also the degree of precipitation, which depends on the sea-ice coverage on the adjacent ocean and the atmospheric circulation pattern. Additionally, the position of the ice margin is controlled by the regional sea level, with transgressions being instrumental for disequilibrating the ice masses, thus leading to enhanced deglaciation by increased iceberg calving.

Future prospects

In order to achieve a better understanding of the interactions at the Antarctic ice margin, and to provide predictions for the reaction of the ice on global climate change, the running investigations shall in international collaboration be expanded on additional oases, be added by investigations on the adjacent continental shelves , and be used for the validation of numerical ice sheet models.

On the basis of our previous studies, new sediment sequences shall be recovered during an expedition with the German RV "Polarstern" in early 2007 from the continental shelf of Prydz Bay as well as from the Rauer Group and Amery Oasis in the hinterland ( see Map ). The samples shall be investigated in close collaboration with national and international partners within the scope of a DFG project that was submitted in Dec. 2005. The results promise a significantly enhanced understanding of the interactions between the glacial history and variations in relative sea level, in climate, and in oceanography along a S-N transect from the inner ice sheet via the coast towards the shelf edge of the Prydz Bay. They shall be used to validate a new numerical model of the Lambert Glacier / Amery Ice Shelf drainage system, the word´s largest fjord system that drains about a quarter of the Antarctic Ice Sheet.