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Greenland ice sheet contribution to sea-level rise from a new-generation ice-sheet model

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Title: Greenland ice sheet contribution to sea-level rise from a new-generation ice-sheet model
Authors: Gillet-Chaulet, F. Browse this author
Gagliardini, O. Browse this author
Seddik, H. Browse this author
Nodet, M. Browse this author
Durand, G. Browse this author
Ritz, C. Browse this author
Zwinger, T. Browse this author
Greve, R. Browse this author →KAKEN DB
Vaughan, D. G. Browse this author
Issue Date: 21-Dec-2012
Publisher: Copernicus Publications
Journal Title: The Cryosphere
Volume: 6
Issue: 6
Start Page: 1561
End Page: 1576
Publisher DOI: 10.5194/tc-6-1561-2012
Abstract: Over the last two decades, the Greenland ice sheet (GrIS) has been losing mass at an increasing rate, enhancing its contribution to sea-level rise (SLR). The recent increases in ice loss appear to be due to changes in both the surface mass balance of the ice sheet and ice discharge (ice flux to the ocean). Rapid ice flow directly affects the discharge, but also alters ice-sheet geometry and so affects climate and surface mass balance. Present-day ice-sheet models only represent rapid ice flow in an approximate fashion and, as a consequence, have never explicitly addressed the role of ice discharge on the total GrIS mass balance, especially at the scale of individual outlet glaciers. Here, we present a newgeneration prognostic ice-sheet model which reproduces the current patterns of rapid ice flow. This requires three essential developments: the complete solution of the full system of equations governing ice deformation; a variable resolution unstructured mesh to resolve outlet glaciers and the use of inverse methods to better constrain poorly known parameters using observations. The modelled ice discharge is in good agreement with observations on the continental scale and for individual outlets. From this initial state, we investigate possible bounds for the next century ice-sheet mass loss. We run sensitivity experiments of the GrIS dynamical response to perturbations in climate and basal lubrication, assuming a fixed position of the marine termini. We find that increasing ablation tends to reduce outflow and thus decreases the icesheet imbalance. In our experiments, the GrIS initial mass (im)balance is preserved throughout the whole century in the absence of reinforced forcing, allowing us to estimate a lower bound of 75mm for the GrIS contribution to SLR by 2100. In one experiment, we show that the current increase in the rate of ice loss can be reproduced and maintained throughout the whole century. However, this requires a very unlikely perturbation of basal lubrication. From this result we are able to estimate an upper bound of 140mm from dynamics only for the GrIS contribution to SLR by 2100.
Rights: http://creativecommons.org/licenses/by/3.0/
Type: article
URI: http://hdl.handle.net/2115/53427
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

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