Quaternary interglacials and the West Antarctic Ice Sheet

Abstract

The Quaternary history and current stability of the marine-based West Antarctic Ice Sheet (WAIS) are discussed, and evidence for and against collapse of the WAIS during interglacial marine oxygen isotope stages (MIS)-5e (ca. 120 kyr ago), MIS-11 (ca. 400 kyr ago), and earlier Pleistocene interglacials is presented. There is no clear evidence supporting the hypothesis of WAIS collapse during MIS-5e, though data unequivocally demonstrating that the WAIS persisted through the penultimate interglacial also are lacking. Recent modeling efforts and ice core analyses suggest significant melting of the Greenland Ice Sheet (GIS) during MIS-Se [Cuffey et al., 2000], which would account for the observed ca. 5 m sea level rise. If this eustatic rise in sea-level exclusively resulted from melting of the GIS, then the WAIS may be less sensitive to sea-level changes than has been widely believed. There now is ample indirect evidence of disintegration of the WAIS during MIS-11, an interglacial of unusually long duration, and there is geologic evidence suggesting at least one earlier WAIS collapse event, during the mid-Pleistocene. In addition to during MIS-11, the WAIS may have disappeared during one of the interglacials associated with the Mid-Pleistocene Revolution, which marks the transition from the 41 kyr Obliquity-dominated world to the 100 kyr Eccentricity-dominated Milankovitch world. Extreme climate shifts and long-duration interglacials are likely to be key factors influencing the long-term behavior of the West Antarctic Ice Sheet. If MIS-11 is a fair analog for the Holocene then future collapse of the WAIS during the current interglacial should be considered a realistic possibility.