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


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タイトル: Greenland ice sheet contribution to sea-level rise from a new-generation ice-sheet model
著者: Gillet-Chaulet, F. 著作を一覧する
Gagliardini, O. 著作を一覧する
Seddik, H. 著作を一覧する
Nodet, M. 著作を一覧する
Durand, G. 著作を一覧する
Ritz, C. 著作を一覧する
Zwinger, T. 著作を一覧する
Greve, R. 著作を一覧する
Vaughan, D. G. 著作を一覧する
発行日: 2012年12月21日
出版者: Copernicus Publications
誌名: The Cryosphere
巻: 6
号: 6
開始ページ: 1561
終了ページ: 1576
出版社 DOI: 10.5194/tc-6-1561-2012
抄録: 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.
資料タイプ: article
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: Greve Ralf


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