An increase in crevasse extent, West Greenland: Hydrologic implications, GRL 38, by William Colgan et al.

Geophysical Research Letters, 38 (2011) L18502;
doi: 10.1029/2011GL048491 

An increase in crevasse extent, West Greenland: Hydrologic implications

 

Key points:

• There has been a significant increase in crevassed area extent
• Crevasse drainage is less efficient in enhancing sliding than moulin drainage
• Increased crevasse extent could also potentially enhance mass loss

William Colgan, Konrad Steffen, W. Scott McLamb, Waleed Abdalati (Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO, U.S.A.), Harihar Rajaram (Department of Civil, Environmental, and Architectural Engineering, University of Colorado at Boulder, Boulder, CO, U.S.A.), Roman Motyka (Geophysical Institute, University of Alaska Fairbanks, Fairbanks, Alaska, USA), Thomas Phillips (Department of Aerospace Engineering Sciences, University of Colorado at Boulder, Boulder, CO, U.S.A.), and Robert Anderson (Institute of Arctic and Alpine Research, University of Colorado at Boulder, Boulder, CO, U.S.A.)

Abstract

We compare high-resolution 1985 and 2009 imagery to assess changes in crevasse extent in the Sermeq Avannarleq ablation zone, West Greenland. The area occupied by crevasses >2 m wide significantly increased (13 ± 4%) over the 24-year period. This increase consists of an expansion of existing crevasse fields, and is accompanied by widespread changes in crevasse orientation (up to 45°). We suggest that a combination of ice sheet thinning and steepening are responsible for the increase in crevasse extent. We examine the potential impact of this change on the hydrology of the ice sheet. We provide a first-order demonstration that moulin-type drainage is more efficient in transferring meltwater fluctuations to the subglacial system than crevasse-type drainage. As enhanced basal sliding is associated with meltwater “pulses,” an increase in crevasse extent can therefore be expected to result in a net decrease in basal sliding sensitivity. An increase in crevasse extent may also accelerate cryo-hydrologic warming and enhance surface ablation.

• 
• 
• 
• 

http://www.agu.org/pubs/crossref/2011/2011GL048491.shtml

Citation: Colgan, W., K.