Modelling the inception of the Patagonian icesheet

We use a coupled climate/icesheet model to simulate the inception and growth of the Patagonian icesheet. Assuming a temperature lowering of 6degreesC and a uniform pressure gradient driving windfields, an icesheet builds up with dimensions and morphology similar to that of the Last Glacial Maximum. Analysis of the stages of growth reveals the following conclusions. Different sectors of the 1800km long icesheet behave differently as a result of latitudinal variations in mass balance; the fastest growth occurs in latitudes 45-52degreesS where the North and South Patagonian Icefields merge and expand to the coast within 1500 model years. The most favourable topography for glacier initiation is the presence of high-elevation basins. Low-elevation summits in the mountain chain take a long time to become covered by ice because of the delay in ice spreading along the main mountain axis. Feedback between the increasing elevation of the icesheet and increasing mass balance on its windward flank enhances the rate of migration of the icesheet towards the precipitation source. There is a lee-side effect whereby easterly mountains are glaciated early on but are then starved of snow as ice builds up to the windward. Such locations should hold an empirical record of the early stages of a glacial cycle (C) 2002 Elsevier Science Ltd and INQUA. All rights reserved.