West Antarctic ice sheet: Waking the sleeping giant?

Antarctic ice sheets

SYMPOSIUM TITLE: Vital Organs in the Earth System: What Is the Prognosis?
PRESENTATION TITLE: West Antarctic Ice Sheet: Waking the Sleeping Giant?
SYMPOSIUM DATE: 19 Feb 2006, 08.30-11.30 am
SYMPOSIUM ORGANISER: International Geosphere-Biosphere Programme, IGBP

The contribution that key regions of the Antarctic ice sheet are making to global sea-level rise is a cause for concern according to Director of British Antarctic Survey (BAS), Professor Chris Rapley. Speaking this week at the AAAS in St Louis he summarised the latest understanding from one of the frozen continent’s most remote and inhospitable corners.

Professor Rapley said, “Parts of the Antarctic ice sheet that rest on bedrock below sea level have begun to discharge ice fast enough to make a significant contribution to sea level rise. Understanding the reason for this change is urgent in order to be able to predict how much ice may ultimately be discharged and over what timescale. Current computer models do not include the effect of liquid water on ice sheet sliding and flow, and so provide only conservative estimates of future behaviour. Only five years ago, Antarctica was characterised as a slumbering giant in terms of climate change. I would argue that this is now an awakened giant and we should take notice.”

In recent years glaciers in the Amundsen Sea sector of the West Antarctic ice sheet and two in East Antarctica have shown rapid thinning. Their common feature is that they all lie on rock well below sea level. The discharge in West Antarctica prompted scientists from BAS, US National Science Foundation and the University of Texas to embark on an airborne geophysical survey of the little visited area of the continent. Using two Twin Otter aircraft kitted out with a suite of survey instruments, the scientists collected data from the Pine Island and Thwaites glaciers and their catchments. These new results provide a quantum jump in our knowledge of the bed topography and internal layering of the ice sheet in the region, and will result in due course in much improved estimates of its future contribution to sea level worldwide.