Global ice volumes at the Last Glacial Maximum and early Lateglacial

Observations of sea levels during the Last Glacial Maximum (LGM) at localit ies far from the former ice margins constrain the global change in ice volu me from the LGM to the present at about 52 x 10(6) km(3). Regional studies of sealevel change from observations near and within the margins of the for mer ice sheets constrain ice volumes of the individual ice sheets and have led to an imbalance between the global estimate of ice volume and the sum o f the individual ice-sheet volumes. The latter estimates are reliable only when the observational record from localities close to the ice mass extends well into Lateglacial times, which is generally not the case for the major ice sheets. Ice volumes during the LGM and earliest part of the Lateglacia l period can therefore be substantially increased without affecting the pre dictions of Lateglacial and Postglacial sea level in a significant manner, provided that a rapid reduction in ice volume occurred in early Lateglacial time. New far-field data for LGM and Lateglacial sea-level change indicate s that a rapid rise in sea level of about 15 m occurred at about 16 500-16 000 C-14 (or 19 200-18 700 calibrated) years ago. This leads to the inferen ce that during the LGM the ice sheet volumes of the major ice sheets were g reater than inferred from regional rebound analyses and that rapid reductio ns in volume occurred at the termination of the LGM. The timing of this occ urrence does not coincide with any recognised Heinrich event, although puls es of ice-rafted debris originating from both northern ice sheets do occur in some high latitude cores. An Antarctic contribution to the post-LGM melt ing event also cannot be ruled out, the timing coinciding with evidence for the onset of warming in southern latitudes and the addition of meltwater i nto the Southern Ocean. (C) 2000 Elsevier Science B.V. All rights reserved.