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Title: Constraints on the geometry of the Antarctic ice sheet during the last interglaciation
Author: Whipple, Matthew R.
ISNI:       0000 0004 6059 3717
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2016
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Uncertainty over future sea level rise is of great concern to society. One useful analogue for future sea levels is the Last Interglaciation (~130-118ka), when global sea level was around 6m higher than present. While most of the expected components to this are well simulated, the magnitude and location of the Antarctic contribution is poorly understood. Here, I perform a variety of ice sheet sensitivity tests to determine constraints on the extent/geometry of the Antarctic ice sheet during the Last Interglaciation in comparison with Antarctic ice core δ180 data and far-field relative sea level data, raised beaches and fossil corals from Patagonia and Australia. The effect of changes in solid earth deformation at ice core sites are simulated using a glacial isostatic adjustment model, and show minimal impact from plausible ice sheet collapses at any considered data sites, and that the ongoing deglacial uplift effects are likely to form a significant component of solid earth elevation around the Ross and Weddell Seas. I use the coupled atmosphere-ocean climate model, HadeM3, to simulate 2kyr snapshot runs for each ice sheet scenario (132-118ka). Precipitation seasonality is very poorly simulated over inland East Antarctica. Modelled changes in temperature between LIG and preindustrial show most similarity to ice core 8180 data when changes in precipitation seasonality are not accounted for. In the event of collapse of any of the marine based West Antarctic, Wilkes, and Aurora basins, cyclonic conditions would dramatically alter local climate, which is not observed in any data, indicating the ice sheet to be in similar to present geometry. Finally, I investigate the effect of glacial-isostasy on the nearest far-field relative sea level data, from Patagonia and Australia. Australian data suggests that there would have to be continual gradual sea level input throughout the Interglaciation. Although a unique fingerprint of West Antarctic collapse might be seen in Patagonian data, uncertain tectonic uplift and deglaciation history means this would be practically impossible to determine. Overall, I am able to determine that the Wilkes or Aurora subglacial basins did not significantly retreat. There remains no data suggesting a West Antarctic collapse in the Last Interglaciation, although the magnitude of global sea level strongly implies some Antarctic contribution.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available