Thermal Evolution of a Holocene Arctic Environment in Western Greenland

We present a Holocene temperature reconstruction at the arctic Greenland Analogue Project (GAP) study area near Kangerlussuaq in western Greenland. The air temperature history is obtained by combining meteorological data from (i) the GAP tundra site, (ii) Kangerlussuaq and coastal sites in South-West Greenland, and (iii) selected Greenland Ice Sheet sites, together with temperature proxy ice-core records. For the glacial stage in the early Holocene, a one-dimensional steady-state ice-sheet model is developed to reproduce the ice thickness and basal thermal conditions of the ice-sheet, and the associated isostatic adjustment. The model uses the geologically-determined ice-margin position and modelled Holocene elevation change of the ice divide. Using the temperature reconstruction and information on present-day vegetation and water bodies, a numerical model, calculating e.g. heat transfer, groundwater flow and salt transport, is used to simulate the thermal evolution of the subsurface including soil and bedrock temperatures, geothermal heat flow and the depth and distribution of permafrost and perennially frozen ground. Seasonal variations in surface processes such as the freezing and thawing of the active layer are taken into account. Comparison with measured soil temperatures and bedrock temperatures measurements down to 570 metres reveals several important factors and processes for the development of permafrost and perennially frozen ground in Greenland.