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TitleRevised estimates of recent mass loss rates for Penny Ice Cap, Baffin Island, based on 2005-2014 elevation changes modified for firn densification
AuthorSchaffer, N; Copland, L; Zdanowicz, C; Burgess, D; Nilsson, J
SourceJournal of Geophysical Research, Earth Surface vol. 125, issue 8, e2019JF005440, 2020 p. 1-17,
Alt SeriesNatural Resources Canada, Contribution Series 20160141
PublisherAmerican Geophysical Union
Mediapaper; on-line; digital
File formatpdf; html
NTS16L; 16M; 26I; 26J; 26K; 26N; 26O; 26P
AreaPenny Ice Cap; Baffin Island
Lat/Long WENS -66.5889 -63.9944 67.4581 66.2489
Subjectshydrogeology; surficial geology/geomorphology; environmental geology; geophysics; Nature and Environment; Science and Technology; glaciers; ice; snow; climate; remote sensing; satellite imagery; geodesy; core samples; statistical analyses; NASA Airborne Topographic Mapper (ATM); Envisat; ice caps; mass balance; firn; climate change; elevations; global positioning systems
Illustrationslocation maps; profiles; tables; geoscientific sketch maps; plots; time series
ProgramClimate Change Geoscience, Glacier Mass Balance Project
Released2020 06 09
AbstractRepeat airborne or satellite measurements of surface elevation over ice caps are often used to calculate glacier-wide surface mass changes over time. However, these measurements typically do not account for vertical ice motion caused by firn densification and/or ice flow, so the effect of these factors for mass change measurements over an entire ice cap are currently poorly constrained. In this study, we update NASA Airborne Topographic Mapper (ATM) altimetry elevation changes across Penny Ice Cap (Baffin Island, Canada) to assess total changes in ice mass from 2005-2014, relative to 199-2000. Dual-frequency GPS measurements and temporal changes in ice core density profiles are used to calculate firn densification and ice flow to isolate the component of elevation change due to surface mass change. Envisat satellite imagery is used to delineate the areas impacted by firn densification. These calculations, the first for a Canadian Arctic ice cap, indicate that accounting for firn densification may reduce the inferred surface mass loss by ~13-15%. Overall, there has been a fourfold increase in mass loss from Penny Ice Cap between 1995-2000 (-1.3 ± 0.7 Gt a-1) and 2005-2013 (-5.4 ± 1.9 Gt a-1). The rapid upglacier migration of the equilibrium line has left large areas of subsurface firn in the current ablation area and has far outpaced the ice flow response, illustrating that the ice cap is not in equilibrium and out of balance with the current climate.
Summary(Plain Language Summary, not published)
Rapid shrinkage of Canada's Arctic ice caps is contributing significantly to global sea-level rise. This study measures changes to the Penny Ice Cap, Baffin Island, NU from airborne measurements of ice cap surface elevation acquired in 2005 and repeated in 2013 and again in 2014. Our estimate of mass loss of ~4.4Gt/a from the Penny Ice Cap since 2005 indicates a 4-fold increase as compared with estimates from the mid 1990's. A novel component to this work is that the height changes derived from the airborne measurements were corrected for effects of enhanced firn compaction and vertical ice flow dynamics. These corrections result in a more accurate estimate of the mass change calculation which would have otherwise been 19% greater if they had not been accounted for. This study highlights the rapid acceleration in which the ice caps of Arctic Canada have responded to recent climate warming and an improvement in the methods commonly used to assess periodic changes in mass of Arctic glaciers.