University of Cambridge > Talks.cam > Scott Polar Research Institute - Physical Sciences Seminar > Calving Laws for Ice Sheet Models - Recent Progress and Future Prospects

Calving Laws for Ice Sheet Models - Recent Progress and Future Prospects

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Calving accounts for most ice losses from the Antarctic Ice Sheet, around half of the losses from the Greenland Ice Sheet, and a substantial amount of the ablation from many high-latitude glaciers and ice caps. Despite this, calving processes are still poorly represented in prognostic ice sheet models, limiting our ability to predict ice-sheet response to climate change. A new approach to quantifying calving losses has been developed, based on the depth of penetration of surface crevasses, which in turn is a function of the velocity field near the glacier margin. The potential of this new approach has been demonstrated in two recent papers, which incorporate crevasse-depth calving laws (CDCLs) in glacier models. First, Nick et al. (2010) conducted a series of experiments with a higher-order flow-line model, and showed that CDC Ls allow a much broader range of glacier behaviour than other ‘calving laws’. Second, Otero et al. (2009) used a static, three-dimensional, higher-order model to successfully predict the calving front position of a small Antarctic glacier. While the success of these implementations is very encouraging, the incorporation of CDC Ls in a time-evolving, three-dimensional higher-order model remains an important goal for the future.

Future development of calving models requires both systematic observations of calving margins and improved modeling routines. Empirical data are urgently needed to determine how well models represent real calving processes and ice-front behaviour, and to identify key areas where improvements are needed. Many issues remain with modeling calving glaciers, but perhaps the most fundamental challenge is to find robust methods of incorporating basal motion (sliding) in higher-order models. It is clear that there are intimate links between calving and glacier dynamics, but realistic, workable ‘sliding laws’ remain elusive. This problem is closely linked with another of glaciology’s ‘last great problems’ – the calculation of evolving subglacial water-pressure fields.

This talk is part of the Scott Polar Research Institute - Physical Sciences Seminar series.

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