The Influence of Marine Topography on the Antarctic Ice Sheet

by Daniel Michael Mullally Jr

Institution: Louisiana State University
Department: Geology & Geophysics
Degree: MS
Year: 2015
Keywords: ice; ice dynamics; antarctica; ice volume; grounding line; topography; bathymetry
Record ID: 2058013
Full text PDF: http://etd.lsu.edu/docs/available/etd-04092015-122012/


The primary controls on Antarctic Ice Sheet (AIS) volume and extent include changes in water temperature, precipitation, atmospheric temperature, and sea level. Here we evaluate the influence of a 5th control, the depth of the continental shelf. Shelf depth affects ice sheet mass balance in the marine environment by controlling the flux of ice that can be exported to the marine environment. This is significant because heat exchange between ocean and ice sheet have been demonstrated to be a dominant control on marine ice volume (Pollard and DeConto, 2009). We used the Parallel Ice Sheet Model (PISM) to simulate AIS dynamics using seven different geologically realistic configurations of a shallower marine scape (i.e., water depth and morphology) to determine how AIS grounding line translations and ice volumes respond to the same climate forcing. Our results show that during advance on an overdeepened and foredeepened shelf, high ablation via calving is such that mass balance is only slightly positive with a net effect of gradual grounding line advance. On a shallow shelf, the relatively low ablation via calving is such that mass balance is more positive the net effect being that grounding line advance is rapid. For grounding line retreat, we see rapid retreat for deep continental shelf configurations and relatively slower retreat on shallow continental shelves. Additionally, the largest ice volumes occur in the configuration with the shallowest continental shelves. As has been recently suggested (Wilson et al., 2013), these results confirm that relative shelf depth is an important factor to consider when using both direct and proxy evidence to reconstruct AIS history