Palaeoclimatology: Ice-sheet history revealed by fossils.

Abstract

Microscopic fossils show that, from 10,400 to 7,500 years ago, upwelling of a water mass called Circumpolar Deep Water destabilized Antarctic ice shelves — a finding that advances our understanding of ice-sheet retreat. See Article p.43 The wind-driven upwelling of Circumpolar Deep Water (CDW) may be destabilizing Antarctic ice shelves, particularly in the region bordering the Amundsen Sea. However, firm evidence that these ice–ocean interactions can persist long enough to cause substantial changes to ice sheets has been lacking. Here, Claus-Dieter Hillenbrand et al. present marine-based palaeoclimate evidence to show that over much of the early Holocene epoch, and since the 1940s, variations in the Southern Hemisphere westerly winds increased the upwelling of CDW. This seemingly led to widespread deglaciations in the region and perhaps even a large ice-shelf collapse. The results confirm that the processes that have long been seen in models were operational in the past.