Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
The Cryosphere, 9, 1579-1600, 2015
http://www.the-cryosphere.net/9/1579/2015/
doi:10.5194/tc-9-1579-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
18 Aug 2015
Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate
S. L. Cornford1, D. F. Martin2, A. J. Payne1, E. G. Ng2, A. M. Le Brocq3, R. M. Gladstone1, T. L. Edwards1, S. R. Shannon1, C. Agosta5,4, M. R. van den Broeke6, H. H. Hellmer7, G. Krinner4, S. R. M. Ligtenberg6, R. Timmermann7, and D. G. Vaughan8 1Centre for Polar Observation and Modelling, School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, UK
2Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
3Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UK
4UJF-Grenoble 1/CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) UMR5183, 38041 Grenoble, France
5Département de Géographie, Université de Liège, Liège, Belgium
6Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, the Netherlands
7Alfred-Wegener-Institut für Polar und Meeresforschung, Bussestrasse 24, 27570 Bremerhaven, Germany
8British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET, UK
Abstract. We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.

Citation: Cornford, S. L., Martin, D. F., Payne, A. J., Ng, E. G., Le Brocq, A. M., Gladstone, R. M., Edwards, T. L., Shannon, S. R., Agosta, C., van den Broeke, M. R., Hellmer, H. H., Krinner, G., Ligtenberg, S. R. M., Timmermann, R., and Vaughan, D. G.: Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate, The Cryosphere, 9, 1579-1600, doi:10.5194/tc-9-1579-2015, 2015.
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Short summary
We used a high-resolution ice sheet model capable of resolving grounding line dynamics (BISICLES) to compute responses of the major West Antarctic ice streams to projections of ocean and atmospheric warming. This is computationally demanding, and although other groups have considered parts of West Antarctica, we think this is the first calculation for the whole region at the sub-kilometer resolution that we show is required.
We used a high-resolution ice sheet model capable of resolving grounding line dynamics...
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