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

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

doi:10.1126/sciadv.aau1380

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

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

Department of Geography and Earth Sciences

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31 Citations (Scopus)

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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

Original language	English
Article number	eaau1380
Journal	Science Advances
Volume	5
Issue number	4
DOIs	https://doi.org/10.1126/sciadv.aau1380
Publication status	Published - 24 Apr 2019

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Ice-stream demise dynamically conditioned by trough shape and bed strengthFinal published version, 3.51 MBLicence: CC BY-NC

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title = "Ice-stream demise dynamically conditioned by trough shape and bed strength",

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",

author = "Tom Bradwell and David Small and Derek Fabel and Rachel Smedley and Clark, {Chris D.} and Saher, {Margot H.} and Callard, {S. Louise} and Chiverrell, {Richard C.} and Dayton Dove and Moreton, {Steven G.} and Roberts, {David H.} and Duller, {G. A. T.} and Cofaigh, {Colm {\'O}.}",

note = "Funding Information: We thank the captain and crew of RRS James Cook (Science Cruise 123), the BGS Marine Operations team on JC123, and S. Morgan (University of Leicester) for operating the Geotek multisensor core logger on the cruise. Bathymetry data in Fig. 3B are from EMODnet. Figure 3 (C and D) contains UKHO bathymetry data provided by U.K. Maritime and Coastguard Agency who are gratefully acknowledged. This research was supported by a NERC UK consortium grant (BRITICE-CHRONO NE/J008672/1). Publisher Copyright: Copyright {\textcopyright} 2019 The Authors.",

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AU - Bradwell, Tom

AU - Small, David

AU - Fabel, Derek

AU - Smedley, Rachel

AU - Clark, Chris D.

AU - Saher, Margot H.

AU - Callard, S. Louise

AU - Chiverrell, Richard C.

AU - Dove, Dayton

AU - Moreton, Steven G.

AU - Roberts, David H.

AU - Duller, G. A. T.

AU - Cofaigh, Colm Ó.

N1 - Funding Information: We thank the captain and crew of RRS James Cook (Science Cruise 123), the BGS Marine Operations team on JC123, and S. Morgan (University of Leicester) for operating the Geotek multisensor core logger on the cruise. Bathymetry data in Fig. 3B are from EMODnet. Figure 3 (C and D) contains UKHO bathymetry data provided by U.K. Maritime and Coastguard Agency who are gratefully acknowledged. This research was supported by a NERC UK consortium grant (BRITICE-CHRONO NE/J008672/1). Publisher Copyright: Copyright © 2019 The Authors.

PY - 2019/4/24

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N2 - 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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Ice-stream demise dynamically conditioned by trough shape and bed strength

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