In:
The Cryosphere, Copernicus GmbH, Vol. 12, No. 11 ( 2018-11-12), p. 3511-3534
Abstract:
Abstract. 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, which themselves are unknown due to
the uncertainty in the projections of future anthropogenic emissions and subsequent climate
response. Here, we aim to improve the understanding of how uncertainties in model
forcing and boundary conditions affect ice sheet model simulations. With use of sampling
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 model
simulations of AIS future 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 variations in bedrock topography. In addition, we find that
over 1.2 m 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
continental ice shelf collapse. Regionally, we find that under our most extreme 100-year warming
experiment generalized for the entire ice sheet, the Amundsen Sea sector is the most significant
source of model uncertainty (1032 mm 6σ spread) and the region with the largest potential
for future sea level contribution (297 mm). In contrast, under a more plausible forcing 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
realization, 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 (161 mm) and to simulation uncertainty (420 mm 6σ spread).
Type of Medium:
Online Resource
ISSN:
1994-0424
DOI:
10.5194/tc-12-3511-2018
DOI:
10.5194/tc-12-3511-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2393169-3
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