Bradwell T, Small D, Fabel D, Smedley RK, Clark CD, Saher MH, Callard SL, Chiverrell RC, Dove D, Moreton SG, Roberts DH, Duller GAT & Ó Cofaigh C (2019) Ice-stream demise dynamically conditioned by trough shape and bed strength. Science Advances, 5 (4), Art. No.: eaau1380. https://doi.org/10.1126/sciadv.aau1380
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.
Science Advances: Volume 5, Issue 4