Publication Date:
2018-06-01
Description:
Estimating the future evolution of the Antarctic Ice Sheet (AIS) is critical for improving future sea level rise (SLR) projections. Numerical ice sheet models are invaluable tools for bounding Antarctic vulnerability; yet, few continental scale projections of century-scale AIS SLR contribution exist, and those that do vary by up to an order of magnitude. This is partly because model projections of future sea level are inherently uncertain and depend largely on the model's boundary conditions and climate forcing. Here, we aim to improve the understanding of how such uncertainties affect ice sheet model simulations. With use of Monte-Carlo style uncertainty quantification techniques embedded within the Ice Sheet System Model (ISSM) framework, we assess how uncertainties in snow accumulation, ocean induced melting, ice viscosity, basal friction, bedrock elevation, and the presence of ice shelves, impact continental scale 100-year projections of AIS sea level contribution. Overall, we find that AIS sea level contribution is strongly affected by grounding line retreat, which is driven by the magnitude of ice shelf basal melt rates and by errors in bedrock topography. In addition, we find that over 1.2 meters of AIS global mean sea level contribution over the next century is achievable, but not likely, as it is tenable only in response to unrealistically large melt rates and instantaneous continental ice shelf collapse. Regionally, we find that under an endmember 100-year warming scenario generalized for the entire ice sheet, the Amundsen Sea Sector is the most significant source of model uncertainty (1032mm 6σ spread). This region also has the largest potential for future sea level contribution (297mm). In contrast, under a more plausible scenario informed regionally by literature and model sensitivity studies, the Ronne basin has a greater potential for local increases in ice shelf basal melt rates. As a result, under this more likely scenario where warm waters reach the continental shelf under the Ronne ice shelf, it is the Ronne basin, particularly the Evans and Rutford Ice Streams, that are the greatest contributors to potential SLR (161mm) and to simulation uncertainty (420mm 6σ spread).
Print ISSN:
1994-0432
Electronic ISSN:
1994-0440
Topics:
Geography
,
Geosciences
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