Ice-stream demise dynamically conditioned by trough shape and bed strength

Bradwell, Tom; Small, David; Fabel, Derek; Smedley, Rachel K.; Clark, Chris C.; Saher, Margot H.; Callard, S. Louise; Chiverrell, Richard C.; Dove, Dayton; Moreton, Steven G.; Roberts, David H.; Duller, Geoff A.T.; Ó Cofaigh, Colm

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.

Citation

Bradwell, T., Small, D., Fabel, D., Smedley, R. K., Clark, C. C., Saher, M. H., Callard, S. L., Chiverrell, R. C., Dove, D., Moreton, S. G., Roberts, D. H., Duller, G. A., & Ó Cofaigh, C. (2019). Ice-stream demise dynamically conditioned by trough shape and bed strength. Science Advances, 5(4), Article eaau1380. https://doi.org/10.1126/sciadv.aau1380

• Journal Article Type: Article
• Acceptance Date: Mar 7, 2019
• Online Publication Date: Apr 24, 2019
• Publication Date: Apr 24, 2019
• Deposit Date: Apr 30, 2019
• Publicly Available Date: May 1, 2019
• Journal: Science Advances
• Publisher: American Association for the Advancement of Science
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 4
• Article Number: eaau1380
• DOI: https://doi.org/10.1126/sciadv.aau1380
• Public URL: https://durham-repository.worktribe.com/output/1302916
• Publisher URL: https://advances.sciencemag.org/content/5/4/eaau1380