Ice-stream demise dynamically conditioned by trough shape and bed strength.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31058217.
- Also identified by DOI 10.1126/sciadv.aau1380 and PMC identifier 6498188.
- Licence recorded as CC BY-NC.
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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.