| Summary: | The aim of this project is to investigate the influence of climate and topography on ice sheets in maritime environments. Numerical models are adapted to simulate the behaviour of the climate and ice sheets in southern Chile and Scotland during the last glaciation. The climate model relates climatic variables to snow accumulation and ablation using an energy balance model. The ice sheet model is based on the continuity equation for ice thickness and relates surface mass exchange to ice thickness and flow. Subsequently, a simple topography model is developed to examine the critical transition between glaciers and ice sheets. The net mass balance gradient in maritime regions is primarily sensitive to temperature and precipitation. Ice sheet initiation is strongly influenced by the adjacent ocean's temperature, which affects the delicate balance between decreasing precipitation and decreasing temperature. In Chile, expanded glaciation reflects an equatorward movement of the prevailing westerlies, though the postulated migration of precipitation belts implies that the maximum depression of the snowline is unlikely to have been contemporaneous at different latitudes. In Scotland, ice sheets appear to be triggered by the southward movement of the North Atlantic polar front. The configuration and latitude of upland topography determines the point of initiation and the threshold between stable upland glaciers and the growth of an ice sheet. The topography acts as a filter between climate and the response of a glacier, and topographic evolution leads to a powerful feedback between topography, climate and ice over Quaternary time scales.
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