Late Pleistocene and Holocene melting history of the Antarctic ice sheet derived from sea-level variations

Spatial and temporal variations of the Late Pleistocene and Holocene sea levels provide important constraints on the melting history of the major ice sheets. In this study, we have examined the sea-level variations at eight sites along the coast of Antarctica to investigate the melting history of Antarctic ice sheet complexes. Comparisons of sea-level variations between observations and predictions due to glacio-hydro-isostatic adjustment suggest that the ice thicknesses removed from the Last Glacial Maximum (LGM) around the Weddell Sea are significantly thicker than those around the Ross Embayment. Sea-level observations also indicate that CLIMAP derived models predict too much relative sea-level change and that consequently ice mass change along the coast has to be scaled down. Improvement of the Late Pleistocene Antarctic ice model is required to evaluate more accurate predictions of present-day geophysical observables associated with this history. Thus, these more accurate predictions can then be subtracted from observables, and the residual field can be analyzed to constrain ongoing mass changes from the ice sheet. We therefore predicted present-day geophysical observables such as the rate of change of solid-surface gravity and crustal movement. These geophysical observables based on the ice models constructed from observed sea-level variations are significantly different from those based on previous models. On the other hand, detailed sea-level observations around Syowa indicate the existence of a sea-level highstand of about 10 m around 40 kyr BP. To investigate these sea-level observations, we have performed preliminary numerical calculations. Comparisons between these observations and predictions indicate the synchronous melting of the northern and southern ice sheets, suggesting a strong link between the melting histories of both polar ice sheets. (C) 2000 Elsevier Science B.V. All rights reserved.