Tuesday 23 August 2005

PB3

PT0132
Control of the Antarctic ice cap by ocean-ice interaction
Bye, John¹
1 School of Earth Sciences, The University Of Melbourne, Vic, Australia
Author email: jbye@unimelb.edu.au
Results will be presented from a simple grounded ice sheet model, in which the net oceanic evaporation influences the ice cap volume in two ways, through changes in: (i) the accumulation rate, and (ii) the mean sea level. The net oceanic evaporation changes are driven by the sea surface temperature(SST) anomaly, and the effects of the waxing and waning of the northern hemisphere ice sheets on sea level are represented through a model of fluvial discharge and ice calving. In contrast to the stable first-order equation which governs changes of the Antarctic ice storage, an unstable first-order equation governs changes in the storage of the northern hemisphere ice sheets. The results of the model show that the Antarctic ice cap volume changes are due mainly to the effects of the northern hemisphere ice sheets on sea level, rather than directly to changes in SST. The sea level predictions, which are driven by the SST time series of Howard (1997) for the subpolar Southern Ocean over the period 220 kyr BP to the present, are similar to those derived from sediment cores in the Red Sea (Siddall et al. 2003),and also provide an explanation for the current observed rate of sea level rise. References: Bye, 1999 Glob. Planet.Change 21 197-213, Howard, 1997 Nature 388 418-419, Oerlemans, 2002 Clim. Dyn. 19 85-93, Siddall et al. 2003 Nature 423 853-858.

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