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Ice stream activity scaled to ice sheet volume during Laurentide Ice Sheet deglaciation

Stokes, C.R.; Margold, M.; Clark, C.D.; Tarasov, L.

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Authors

M. Margold

C.D. Clark

L. Tarasov



Abstract

The contribution of the Greenland and West Antarctic ice sheets to sea level has increased in recent decades, largely owing to the thinning and retreat of outlet glaciers and ice streams1, 2, 3, 4. This dynamic loss is a serious concern, with some modelling studies suggesting that the collapse of a major ice sheet could be imminent5, 6 or potentially underway7 in West Antarctica, but others predicting a more limited response8. A major problem is that observations used to initialize and calibrate models typically span only a few decades, and, at the ice-sheet scale, it is unclear how the entire drainage network of ice streams evolves over longer timescales. This represents one of the largest sources of uncertainty when predicting the contributions of ice sheets to sea-level rise8, 9, 10. A key question is whether ice streams might increase and sustain rates of mass loss over centuries or millennia, beyond those expected for a given ocean–climate forcing5, 6, 7, 8, 9, 10. Here we reconstruct the activity of 117 ice streams that operated at various times during deglaciation of the Laurentide Ice Sheet (from about 22,000 to 7,000 years ago) and show that as they activated and deactivated in different locations, their overall number decreased, they occupied a progressively smaller percentage of the ice sheet perimeter and their total discharge decreased. The underlying geology and topography clearly influenced ice stream activity, but—at the ice-sheet scale—their drainage network adjusted and was linked to changes in ice sheet volume. It is unclear whether these findings can be directly translated to modern ice sheets. However, contrary to the view that sees ice streams as unstable entities that can accelerate ice-sheet deglaciation, we conclude that ice streams exerted progressively less influence on ice sheet mass balance during the retreat of the Laurentide Ice Sheet.

Citation

Stokes, C., Margold, M., Clark, C., & Tarasov, L. (2016). Ice stream activity scaled to ice sheet volume during Laurentide Ice Sheet deglaciation. Nature, 530(7590), 322-326. https://doi.org/10.1038/nature16947

Journal Article Type Article
Acceptance Date Dec 16, 2015
Online Publication Date Feb 17, 2016
Publication Date Feb 17, 2016
Deposit Date Apr 5, 2016
Publicly Available Date Mar 29, 2024
Journal Nature
Print ISSN 0028-0836
Electronic ISSN 1476-4687
Publisher Nature Research
Peer Reviewed Peer Reviewed
Volume 530
Issue 7590
Pages 322-326
DOI https://doi.org/10.1038/nature16947

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