HR: 11:50h
AN: C42A-07    [Abstracts]
TI: East Antarctic Ice Sheet: Stability Since the mid Holocene and Vulnerability to Sea Level Change
AU: * Mackintosh, A
EM: andrew.mackintosh@vuw.ac.nz
AF: School of Geography, Environment and Earth Sciences and Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington, Wel 6140, New Zealand
AU: White, D
EM: dwhite@els.mq.edu.au
AF: Department of Physical Geography, Macquarie University, North Ryde, Sydney, NSW 2109, Australia
AU: Fink, D
EM: fink@ansto.gov.au
AF: Australian Nuclear Science and Technology Organisation, PMB 1 Menai, Sydney, NSW 2234, Australia
AU: Gore, D
EM: damian.gore@mq.edu.au
AF: Department of Physical Geography, Macquarie University, North Ryde, Sydney, NSW 2109, Australia
AB: The East Antarctic Ice Sheet (EAIS), the world's largest, locks up approximately 60 m of eustatic sea level equivalent. Although thought to be less vulnerable than the Greenland or West Antarctic Ice Sheets, its continental scale means that small changes in its volume can have a major influence on global sea level. Cosmogenic exposure dating of glacial erratics in the Framnes Mountains indicates that the EAIS margin stabilised around 7-6,000 years ago, at a time when eustatic sea level approached near-modern levels. This is in contrast to the West Antarctic Ice Sheet, which continued to retreat throughout the Holocene. The similarity in timing between stability of the EAIS margin and the slowdown in post-glacial sea level rise supports a long- standing hypothesis, recently demonstrated by ice sheet modelling, that EAIS volume changes over glacial/interglacial cycles are dominantly forced by sea level changes. This is because the EAIS margin is presently too cold to experience much direct ablation through melting, and the dominant mode of ice loss is iceberg calving. The ice sheet is "interlocked by global sea level": Sea level fall allows for thickening and expansion of the ice margin. Conversely, sea level rise causes increased calving of the ice margin and retreat. The apparent sea-level control on the EAIS, now demonstrated by both ice sheet modelling and empirical evidence poses the question; Is the EAIS vulnerable to present-day sea level rise associated with thermal expansion of the oceans, melting valley glaciers and increasing ice fluxes in Greenland and West Antarctica? Or is the circa 1 m sea level rise predicted for this century too small to influence the EAIS?
UR: http://www.vuw.ac.nz/geo/people/andrew-mackintosh/index.html
DE: 0726 Ice sheets
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1621 Cryospheric change (0776)
DE: 1641 Sea level change (1222, 1225, 4556)
SC: Cryosphere [C]
MN: 2007 Fall Meeting