Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate

• Published in: The Cryosphere
• Main Authors: 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., Vaughan, D.G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications on behalf of the European Geosciences Union 2015
• Subjects: Antarctic; Amundsen Sea; West Antarctic Ice Sheet; Antarc*; Ice Sheet; Ice Shelf; Ice Shelves; The Cryosphere
• Online Access: http://nora.nerc.ac.uk/id/eprint/510626/; https://nora.nerc.ac.uk/id/eprint/510626/1/tc-9-1579-2015.pdf; https://tc.copernicus.org/articles/9/1579/2015/

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. Each of the simulations begins with a geometry and velocity close to present day observations, and evolves according to variation in meteoric ice accumulation, ice shelf melting, and mesh resolution. 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 rates 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, 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. Sensitivity to mesh resolution is spurious, and we find that sub-kilometer resolution is needed along most regions of the grounding line to avoid systematic under-estimates of the retreat rate, although resolution requirements are more stringent in some regions – for example the Amundsen Sea Embayment – than others – such as the Möller and Institute ice streams.