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TitleChanges in accumulation-area firn stratigraphy and meltwater flow during a period of climate warming: Devon Ice Cap, Nunavut, Canada
AuthorGascon, G; Sharp, M; Burgess, DORCID logo; Bezeau, P; Bush, A B G
SourceJournal of Geophysical Research vol. 118, 2013 p. 2380-2391, Open Access logo Open Access
Alt SeriesEarth Sciences Sector, Contribution Series 20130131
Mediapaper; on-line; digital
File formatpdf
NTS48H/03; 48H/06
AreaDevon Ice Cap; Devon Island
Lat/Long WENS -82.9167 -82.5833 75.3333 75.1667
Subjectsgeophysics; surficial geology/geomorphology; environmental geology; stratigraphy; Nature and Environment; climate, arctic; climate; meltwater channels; ice; ice conditions; ice thickness; Climate change; Cenozoic; Quaternary
Illustrationslocation maps; profiles; tables
ProgramClimate Change Geoscience
Released2013 11 14
AbstractTo document climate-driven changes in firn stratigraphy and their implications for meltwater flow patterns within firn on the Devon Ice Cap, Nunavut, during the 21st century summer warming, 500MHz ground-penetrating radar (GPR) surveys were conducted along a 40 km transect in each spring from 2007 to 2012. These linear GPR surveys were supplemented by four 190m by 100m GPR grid surveys and 36 firn cores. Increased meltwater percolation and infiltration ice formation associated with high surface melt rates since 2005 modified the firn stratigraphy substantially over a horizontal distance of nearly 30 km. The most dramatic change involved the growth of a thick ice layer within the firn body. This layer grew primarily by upward accretion over an initial widespread ice layer formed during summer 2005. It thickened by between 0.5 and 4.5m over the study period and filled much of the pore volume in the upper part of the firn, reducing vertical percolation of meltwater into deeper sections of the firn and thus the water storage potential of much of the firn reservoir. Heterogeneous percolation of surface meltwater promoted by rolling topography played an important role in meltwater infiltration and drainage, encouraging lateral flow at the tops of small hills and ponding and refreezing of meltwater beneath surface depressions.
Summary(Plain Language Summary, not published)
This study documents increased rates of densification of the near surface firn pack along a 50 km transect across the Devon ice cap, Nunavut from repeat ground penetrating radar surveys conducted between 2007 and 2012. Firn is relatively low density (300 - 600 kg m-3) snow that is greater than 1 year old and has experienced varying degrees of densification from the overlying snow pack and from internal refreezing of meltwater generated on the ice cap surface. Excessively warm summer temperatures since 2005 has resulted in accelerated rates of firn densification and thickening of internal ice layering above ~1400 m a.s.l. on the Devon ice cap, as identified in this study. These observations effectively highlight the impact of recent warming on Canadian ice caps and provide important information as to how polar ice caps will respond to further warming trends predicted for this region.

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