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Julian Dowdeswell, University of Cambridge (United Kingdom)
Martin Sharp, University of Alberta (Canada)
Andrey Glazovsky, Russian Academy of Sciences (Russian Federation)
Toby Benham, University of Cambridge (United Kingdom)
Jon Ove Hagen, University of Oslo (Norway)
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Satellite radar interferometry, 60 MHz airborne ice-penetrating radar data, and visible-band satellite imagery were used to calculate the velocity structure, ice thickness, and changing ice-marginal extent of several Arctic ice caps (Austfonna, Academy of Sciences Ice Cap and Canadian ice caps). Ice-cap motion is less than about 10 m yr-1, except where faster-flowing curvilinear features with velocities of several tens to over a few hundred m yr-1 are present. Most drainage basins of these ice caps have undergone ice-marginal retreat over the past few decades at an average of a few tens of metres per year. Iceberg flux from the marine margins of Austfonna, Svalbard (8,100 km2), is about 2.5 ± 05 km3 yr-1 (w.e.), about 45% of the total calving flux from the whole Svalbard archipelago. Iceberg flux should be included in calculations of the total mass balance of the many large Arctic ice caps, including those located in the Russian and Canadian Arctic that end in tidewater. The neglect of this term has led to underestimates of mass loss from these ice caps and, thus, to underestimates of the contribution of Arctic ice caps to global sea-level rise.
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