The potential contributions of the Antarctic ice sheet to sea-level rise over the next 3,000 years are modelled in a study published in this week’s Nature. Changes in atmospheric and oceanic temperature may cause changes in ice melt rates, owing to the exchange of heat between ice and adjacent water or air. However, it is difficult to quantify the contribution of large ice sheets to sea-level rise under projected warming scenarios, partly because of computational restrictions.
Nicholas Golledge and colleagues use a coupled ice-sheet/ice-shelf model to simulate the response of the present-day Antarctic ice-sheet system to oceanic and climate changes for four representative concentration pathways of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report. Although there are uncertainties in the modelling, the simulations suggest that atmospheric warming of 2 degrees Celsius, coupled with prolonged ocean warming of 0.5 degrees Celsius above present, could lead to the loss of 80 to 85 per cent of all floating ice in Antarctica.
Across all the examined IPCC scenarios, the authors find that sea-level rise resulting from Antarctic ice-sheet melt may range from about 0.1 to 3 metres by the year 2300 and about 0.4 to 9 metres by the year 5000. This large range in estimates reflects both methodological uncertainty and a wide span of potential levels of emissions of greenhouse gases.
Victoria University of Wellington, Wellington, New Zealand
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