Modelled ice-sheet margins of three Greenland ice-sheet models compared with a geological record from ice-marginal deposits in central West Greenland
Icee-sheet modelling is an essential tool for estimating the effect of climate change on the Greenland ice sheet. The large spatial and long-term temporal scales of the ice-sheet model limits the amount of data which can be used to test model results. The geological record is useful because it provi...
| Published in: | Annals of Glaciology |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
International Glaciological Society
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| Subjects: | |
| Online Access: | http://hdl.handle.net/2115/47940 https://doi.org/10.1017/s0260305500013252 |
| Summary: | Icee-sheet modelling is an essential tool for estimating the effect of climate change on the Greenland ice sheet. The large spatial and long-term temporal scales of the ice-sheet model limits the amount of data which can be used to test model results. The geological record is useful because it provides test material on the time-scales typical for the memory of ice sheets (millennia). This paper compares modelled ice-margin positions with a geological scenario of ice-margin positions since the Last Glacial Maximum to the present in West Greenland. Morphological evidence of ice-margin positions is provided by moraines. Moraine systems are dated by 14C-dated marine shells and terrestrial peat. Three Greenland ice-sheet models are compared. There are distinct differences in modelled ice-margin positions between the models and between model results and the geological record . Disagreement between models and the geological record in the near-coastal area is explained by the inadequate treatment of marginal processes in a tide-water environment. A smaller than present ice sheet a round the warm period in the Holocene (Holocene climatic optimum) only occurs if such a period a ppears in the forcing (ice-core record ) or used temporal resolution. Smoothing of the GRIP record with a 2000 year average eliminates the climatic signal related to the Holocene climatic optimum. This underlines the importance of short-term and medium-term variations (decades, centuries) in climatic variables in determining ice-margin positions in the past but also in the future. |
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