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Durham University

Department of Geography

Departmental Research Projects

Publication details

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. Journal of Glaciology. 2015;61:137-150.

Author(s) from Durham

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.

Department of Geography