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Basal topographic controls on rapid retreat of Humboldt Glacier, northern Greenland

Carr, J.R.; Vieli, A.; Stokes, C.R.; Jamieson, S.S.R.; Palmer, S.J.; Christoffersen, P.; Dowdeswell, J.A.; Nick, F.M.; Blankenship, D.D.; Young, D.A.

Basal topographic controls on rapid retreat of Humboldt Glacier, northern Greenland Thumbnail


Authors

J.R. Carr

A. Vieli

S.J. Palmer

P. Christoffersen

J.A. Dowdeswell

F.M. Nick

D.D. Blankenship

D.A. Young



Abstract

Discharge from marine-terminating outlet glaciers accounts for up to half the recent mass loss from the Greenland ice sheet, yet the causal factors are not fully understood. Here we assess the factors controlling the behaviour of Humboldt Glacier (HG), allowing us to evaluate the influence of basal topography on outlet glacier response to external forcing since part of HG’s terminus occupies a large overdeepening. HG’s retreat accelerated dramatically after 1999, coinciding with summer atmospheric warming of up to 0.19°C a–1 and sea-ice decline. Retreat was an order of magnitude greater in the northern section of the terminus, underlain by a major basal trough, than in the southern section, where the bedrock is comparatively shallow. Velocity change following retreat was spatially non-uniform, potentially due to a pinning point near HG’s northern lateral margin. Consistent with observations, numerical modelling demonstrates an order-of-magnitude greater sensitivity to sea-ice buttressing and crevasse depth (used as a proxy for atmospheric warming) in the northern section. The trough extends up to 72 km inland, so it is likely to facilitate sustained retreat and ice loss from HG during the 21st century.

Citation

Carr, J., Vieli, A., Stokes, C., Jamieson, S., Palmer, S., Christoffersen, P., …Young, D. (2015). Basal topographic controls on rapid retreat of Humboldt Glacier, northern Greenland. Journal of Glaciology, 61(225), 137-150. https://doi.org/10.3189/2015jog14j128

Journal Article Type Article
Online Publication Date Jul 10, 2017
Publication Date Feb 1, 2015
Deposit Date Jan 27, 2015
Publicly Available Date Feb 16, 2015
Journal Journal of Glaciology
Print ISSN 0022-1430
Electronic ISSN 1727-5652
Publisher International Glaciological Society
Peer Reviewed Peer Reviewed
Volume 61
Issue 225
Pages 137-150
DOI https://doi.org/10.3189/2015jog14j128
Keywords Arctic glaciology, Atmosphere/ice/ocean interactions, Glacier calving, Glacier fluctuations, Glacier modelling.

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