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 le vels provide important constraints on the melting history of the major ice sheets. In this study, we have examined the sea-level variations at eight s ites along the coast of Antarctica to investigate the melting history of An tarctic ice sheet complexes. Comparisons of sea-level variations between ob servations and predictions due to glacio-hydro-isostatic adjustment suggest that the ice thicknesses removed from the Last Glacial Maximum (LGM) aroun d the Weddell Sea are significantly thicker than those around the Ross Emba yment. Sea-level observations also indicate that CLIMAP derived models pred ict too much relative sea-level change and that consequently ice mass chang e along the coast has to be scaled down. Improvement of the Late Pleistocen e Antarctic ice model is required to evaluate more accurate predictions of present-day geophysical observables associated with this history. Thus, the se more accurate predictions can then be subtracted from observables, and t he residual field can be analyzed to constrain ongoing mass changes from th e ice sheet. We therefore predicted present-day geophysical observables suc h as the rate of change of solid-surface gravity and crustal movement. Thes e geophysical observables based on the ice models constructed from observed sea-level variations are significantly different from those based on previ ous 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 ky r BP. To investigate these sea-level observations, we have performed prelim inary numerical calculations. Comparisons between these observations and pr edictions indicate the synchronous melting of the northern and southern ice sheets, suggesting a strong link between the melting histories of both pol ar ice sheets. (C) 2000 Elsevier Science B.V. All rights reserved.