Position Analysis:Polar Ice Sheets and Climate Change
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Title:
Position Analysis:Polar Ice Sheets and Climate Change Global Impacts
Creator:
Antarctic Climate & Ecosystems Cooperative Research Centre
Publisher:
Antarctic Climate&Ecosystems Cooperative Research Centre
Publication Date:
Language:
English

Notes

Abstract:
Change in the mass of freshwater locked up as ice in Antarctica and Greenland has the greatest potential to affect global sea level in a warming world. Modern satellite techniques are providing increasingly accurate evidence that mass loss from the polar ice sheets is contributing to current sea-level rise. This loss is due to increased discharge of ice by the large glaciers draining the ice sheets as well as greater surface melting. The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC , 2007) estimated the maximum projected total sea-level rise from 1980–1999 to 2090–2099, excluding any accelerated ice discharge from polar ice sheets, as 0.59 metres. The IPCC AR4 also considered that a further 0.20 m of sea-level rise might occur over that interval from dynamic changes to ice flow increasing discharge from the ice sheets, and that even larger values could not be excluded. The processes that might cause this increase are not fully understood or adequately included in present ice sheet models. The extent of such an increase is probably the largest unknown in the projections of sea-level rise over the next century. Since the IPCC AR4, there have been further observations of increasing ice flow, highlighting the potential for future dynamic changes in the ice sheets. In the absence of well validated models, a wide range of heuristic projections for the maximum 21st century sea-level rise have been advanced. Hansen (2007) suggested that 5 m of sea-level rise is not beyond question, although other researchers (Pfeffer et al. 2008) challenge this, while Alley et al. (2008) comment on a worrying lack of agreement among these projections. Sea-level rise, with associated effects such as increased frequency of severe storm surges, will be one of the greatest impacts of a warming world on human societies. Even if global warming stabilises, the ice sheets will continue to add to sea level for many centuries into the future. The melting of ice sheets also freshens the ocean water, with consequent impacts on ocean circulation (and hence global climate), marine environments, and the rate at which the ocean absorbs greenhouse gases such as carbon dioxide from the atmosphere. The aim of this paper is threefold: 1. T o outline the likely effect of global warming on the polar ice sheets, and the potential impacts of ice sheet change on sea level; 2. T o inform Australian governments of recent developments in scientific research into ‘ice sheet mass balance’; and 3. T o identify issues for consideration in policy development.

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Source Institution:
Florida International University
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Aggregations:
Sea Level Rise