Termination of last interglacial episode and the Wilson Antarctic surge hypothesis

Abstract

WILSON'S theory¹ that Pleistocene glaciations might be initiated by massive surges of the East Antarctic ice sheet has been supported on climatological grounds by Flohn², and Hollin³ outlines several geological tests of the idea. If a surge occurred, sea level would rise rapidly by many metres and, according to Hollin and Flohn, the oceans would cool significantly—especially the Atlantic. The sea-level rise would quickly be followed by falling sea level as northern continental ice sheets developed. Numerical values approximately would be (1) sea-level rise of 10–20 m over a surge period of several hundred years³; (2) global cooling of about 1° by virtue of the albedo of the greatly increased floating ice-field in sub-Antarctic waters produced by the surge², and (3) the high sea level should persist for no more than a few hundred years as northern continental glaciation is envisaged as starting to form when the peak is reached, if not before, and this ice volume is likely to equal many metres of sea-level equivalent after 1,000yr(refs 2,3). An alternative surge hypothesis for glacial initiation by Mercer⁴ invokes rapid disintegration of the West Antarctic ice sheet—believed to be inherently unstable because its base is extensively below sea level⁵. Rapid disintegration would cause a sea-level rise of about 5 m, perhaps as rapid but smaller in magnitude than Wilson's East Antarctic surge, followed about 1,000 yr later by mild warming (0.5–1 °C) of equatorial Atlantic temperatures as production ceased of Weddell Sea bottom water⁶. The time lag between West Antarctic ice disintegration and northern glacial initiation is uncertain under this hypothesis, but may be a few thousand years if circulation changes of the deep Atlantic ocean are involved. Evidence presented here of sea-level changes and temperature variation argues against the Wilson hypothesis but does not preclude all ‘surge’ mechanisms.