Ice-stream demise dynamically conditioned by trough shape and bed strength
Bradwell, T.; Small, D.; Fabel, D.; Smedley, R.K.; Clark, C.D.; Saher, M.H.; Callard, S.L.; Chiverrell, R.C.; Dove, D.; Moreton, S.G.; Roberts, D.H.; Duller, G.A.T.; Ó Cofaigh, C. (2019). Ice-stream demise dynamically conditioned by trough shape and bed strength. Science Advances 5(4): eaau1380. https://dx.doi.org/10.1126/sciadv.aau1380
In: Science Advances. AAAS: New York. ISSN 2375-2548; e-ISSN 2375-2548, more
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| Authors | | Top |
- Bradwell, T.
- Small, D.
- Fabel, D.
- Smedley, R.K.
- Clark, C.D.
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- Saher, M.H.
- Callard, S.L.
- Chiverrell, R.C.
- Dove, D.
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- Moreton, S.G.
- Roberts, D.H.
- Duller, G.A.T.
- Ó Cofaigh, C.
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| Abstract |
Ice sheet mass loss is currently dominated by fast-flowing glaciers (ice streams) terminating in the ocean as ice shelves and resting on beds below sea level. The factors controlling ice-stream flow and retreat over longer time scales (>100 years), especially the role of three-dimensional bed shape and bed strength, remain major uncertainties. We focus on a former ice stream where trough shape and bed substrate are known, or can be defined, to reconstruct ice-stream retreat history and grounding-line movements over 15 millennia since the Last Glacial Maximum. We identify a major behavioral step change around 18,500 to 16,000 years ago—out of tune with external forcing factors—associated with the collapse of floating ice sectors and rapid ice-front retreat. We attribute this step change to a marked geological transition from a soft/weak bed to a hard/strong bed coincident with a change in trough geometry. Both these factors conditioned and ultimately hastened ice-stream demise. |
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