Ice Sheet Mass Transport in the Earth System
Abstract
Fluctuations in the mass of the polar ice sheets are of considerable societal importance, because they affect global sea levels and oceanic conditions. They occur as a consequence of their internal dynamics, and changes in atmospheric and oceanic conditions. Analysis of the geological record suggests that past climatic changes have precipitated sustained ice sheet contributions, in excess of 10 mm yr-1 over millennial time periods, and the prospect of such changes in the future are of greatest concern. Even the modest rises in ocean temperature that are predicted over the coming century, could trigger significant ice sheet mass loss through enhanced melting of ice shelves (8-10) and outlet glaciers . However, these processes were not incorporated into the ice sheet models that informed the current global climate projections. Until this is achieved with demonstrated reliability, observations of ice sheet mass imbalance remain essential in determining their contribution to sea level. Satellite geodesy has revolutionised the manner in which ice sheet mass balance is estimated. Since 1998, there have been at least 28 published ice sheet mass balance estimates, based variously on the satellite techniques of altimetry, interferometry, and gravimetry. These estimates, and their respective uncertainties, allow for a combined Greenland and Antarctic ice sheet mass imbalance of between -676 and +69 Gt yr-1, equivalent to a mean global sea level contribution in the range of +1.9 to -0.2 mm yr-1. However, much of this spread, which is large in comparison to other ice sheet imbalance assessments and to the estimated rate of global sea level rise, is due to the brevity of many satellite surveys (4.5 years, on average) relative to the rate at which ice sheet mass has fluctuated. Because the various satellite methods for estimating ice sheet mass balance differ in their strengths and weaknesses , careful consideration ought to make them complementary. In this presentation, we compare and combine estimates of ice sheet mass balance derived from all three satellite geodetic techniques, using common spatial and temporal domains, to investigate the extent to which the approaches concur, and to produce a reconciled estimate of ice sheet mass balance.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.G43C..01S
- Keywords:
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- 0726 CRYOSPHERE / Ice sheets;
- 0762 CRYOSPHERE / Mass balance;
- 1240 GEODESY AND GRAVITY / Satellite geodesy: results