In:
The Cryosphere, Copernicus GmbH, Vol. 12, No. 11 ( 2018-11-23), p. 3635-3651
Abstract:
Abstract. Uncertainties
in future sea level projections are dominated by our limited understanding of
the dynamical processes that control instabilities of marine ice sheets. The
last deglaciation of the British–Irish Ice Sheet offers a valuable example
to examine these processes. The Minch Ice Stream, which drained a large
proportion of ice from the northwest sector of the British–Irish Ice Sheet
during the last deglaciation, is constrained with abundant empirical data
which can be used to inform, validate, and analyse numerical ice sheet
simulations. We use BISICLES, a higher-order ice sheet model, to examine the
dynamical processes that controlled the retreat of the Minch Ice Stream. We
perform simplified experiments of the retreat of this ice stream under an
idealised climate forcing to isolate the effect of marine ice sheet
processes, simulating retreat from the continental shelf under constant
“warm” surface mass balance and sub-ice-shelf melt. The model simulates a
slowdown of retreat as the ice stream becomes laterally confined at the mouth
of the Minch strait between mainland Scotland and the Isle of Lewis,
resulting in a marine setting similar to many large tidewater glaciers in
Greenland and Antarctica. At this stage of the simulation, the presence of an
ice shelf becomes a more important control on grounded ice volume, providing
buttressing to upstream ice. Subsequently, the presence of a reverse slope
inside the Minch strait produces an acceleration in retreat, leading to a
“collapsed” state, even when the climate returns to the initial “cold”
conditions. Our simulations demonstrate the importance of the marine ice
sheet instability and ice shelf buttressing during the deglaciation of parts
of the British–Irish Ice Sheet. We conclude that geological data could be
applied to further constrain these processes in ice sheet models used for
projecting the future of contemporary ice sheets.
Type of Medium:
Online Resource
ISSN:
1994-0424
DOI:
10.5194/tc-12-3635-2018
DOI:
10.5194/tc-12-3635-2018-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2393169-3
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