Modelled ice-sheet margins of three Greenland ice-sheet models compared with a geological record from ice-marginal deposits in central West Greenland

• Published in: Annals of Glaciology
• Main Authors: Tatenhove, Frank G. M. van, Fabre, Adeline, Greve, Ralf, Huybrechts, Philippe
• Format: Article in Journal/Newspaper
• Language: English
• Published: International Glaciological Society
• Subjects: 450; Greenland; Annals of Glaciology; GRIP; ice core; Ice Sheet
• Online Access: http://hdl.handle.net/2115/47940; https://doi.org/10.1017/s0260305500013252

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.