Sprucing Up Greenland

摘要

How much did the Greenland ice sheet shrink during previous warm episodes of the Pleistocene (from ～1.8 million to ～11,000 years ago)? This question is central to understanding fluctuations in sea level and the future stability of the ice sheet. On page 1622 of this issue, de Vernal and Hillaire-Marcel (7) report a record of pollen preserved in marine sediments deposited beyond the ice sheet's margin that sheds considerable new light on the problem. The Pleistocene was characterized by long periods of extensive Northern Hemisphere glaciation, interrupted by relatively brief interglacials during which continental ice retreated to a few strongholds in the Canadian Arctic and Greenland.