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Behaviour of an interactive Greenland ice sheet in HADCM3

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Citation:
Ridley, J. , Huybrechts, P. , Gregory, J. and Lowe, J. (2004): Behaviour of an interactive Greenland ice sheet in HADCM3 , European Geosciences Union First General Assembly, Nice (F)April 2004. .
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Abstract:

The HadCM3 OAGCM has been interactively coupled to a dynamic 3-D ice sheetmodel of Greenland and includes a visco-elastic solid Earth model, in which theGCM provides precipitation and temperature anomalies to the ice sheet model onceper year. The anomalies are interpolated on to the grid of the ice sheet model, whichthen calculates ablation, based on a degree-day scheme, ice dynamics and basalrebound. The ice sheet model determines a new orography and fresh water fluxeswhich are utilised by the GCM over the subsequent year. Iceberg calving fluxes areapplied evenly to the ocean region adjacent to Greenland whilst runoff enters theocean through river outlets.A multiple century experiment starting from the present day ice sheet, with 4 timespre-industrial atmospheric concentration of CO2 has been concluded. The modelledsurface air temperature over Greenland in the 4 x CO2 climate is 8.3 degrees warmerthan in the modelled pre-industrial climate, as compared with the global changeof 5.2 degrees. Precipitation over Greenland is increased by 33% but the rate ofablation rises by 640%, causing an additional sea-level rise of 5.1mm per year. Withthe exception of a small residual ice cap on the tops of the eastern mountains, theice sheet is completely ablated within 3000 years. The local effect, of the meltingice sheet, is to increase Greenland surface temperatures by 15 degrees, leading towarmer air in the central Arctic and a general thinning of the sea-ice. The orographicchange results in a southward redirection of the storm tracks in the Norwegian Seaand a subsequent cooling around Svalbard. Changes to the global climate system arenegligible, the North Atlantic overturning stream function is unchanged.

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