Climate sensitivity of the ice cap of King George Island, South Shetland Islands, Antarctica

Abstract

A two-dimensional vertically integrated ice-flow model has been used to simulate the current state of the ice cap of King George Island, South Shetland Islands, Antarctica, as well as the sensitivity of this state to climate change. The model was forced by an energy-balance model that generates the specific mass balance from climatological input data of two research stations. It proved difficult to simulate satisfactorily the entire geometry of the present-day ice cap. Nevertheless, it was possible to simulate a steady-state ice cap whose volume and areal extent approximate the (estimated) current situation. Several experiments have indicated that this state is highly sensitive to climate change. The model predicts that cooling by l K will increase the ice volume by 10% and warming by l K will decrease it by 36%. A 10% change in precipitation will alter the ice volume by less than 8%. Application of the IPCC-90 Business-as-Usual scenario leads to a 55% reduction in the ice volume by the year AD 2100, compared to the present-day situation. The response of the ice cap to warming is therefore totally different from the response of the main Antarctic ice sheet which is believed to gain mass by increasing temperatures.