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RECENT CHANGES IN THE ICE CAPS AND GLACIERS OF CANADA'S ARCTIC ISLANDS

SHARP, MARTIN  University of Alberta.
Copland, Luke  Gateway Antarctica, University of Canterbury.
Burgess, David  University of Alberta.
Williamson, Scott  University of Alberta.
Filbert, Katie  University of Alberta.
Cawkwell, Fiona  University of Alberta.

The Queen Elizabeth Islands in Arctic Canada contain over 110,000 km2 of ice caps and glaciers, the largest area of land ice in the world outside Antarctica and Greenland (Williams and Ferrigno, 2002). These ice masses are located in a region that is projected to experience large climate warming over the next century due to the build-up of greenhouse gases in the atmosphere (IPCC, 2001). These small ice masses are likely to respond more rapidly to respond more rapidly to the projected warming than the larger Greenland ice sheet, and may contribute appreciably to sea level changes over the next century.

To provide a baseline against which future changes can be assessed, and to determine whether changes in glacier area and volume are already underway, we compared the extent of ice cover in the Queen Elizabeth Islands in 1959/60 with that in 1999/2000. 1959/60 ice extent was derived from Digital NTDB (National Topographic Database) ice outlines provided by Geomatics Canada. These outlines are available as a commercial product, and were derived from the digitization of 1:250,000 topographic maps, which in turn were plotted from 1:60,000 stereo aerial photography flown in 1959/60. The ice outlines were provided in ArcView shapefile format in both latitude/longitude and projected UTM formats. The 1999/2000 ice outlines were derived from automatic (unsupervised) classification of orthorectified Landsat 7 imagery. It was not possible to measure the present-day ice extent in the far northern part of Ellesmere Island due to the lack of Landsat imagery above ~82°N. The vast majority of the ice in N. Ellesmere Island (93.1%) was, however, imaged. The total ice area in N. Ellesmere in 1959/60 was 28,062 km2, of which 26,131 km2 could be seen in the Landsat 7 imagery.

This paper will present the results of the change analysis, and discuss the observed regional patterns in rates of change. It will also discuss relationships between patterns of change and ice dynamics. Volume-area scaling methods (Bahr and others, 1997) will be used to make an initial estimate of the changes in ice volume since 1960. An estimate of the contribution of these changes to global sea level will also be presented.

REFERENCES
Bahr, D.B., M.F. Meier and S.D. Peckham., 1997, The physical basis of glacier volume-area scaling: Journal of Geophysical Research, v102,p. 355-362.

IPCC., 2001, Climate Change 2001: The Scientific Basis. Cambridge, Cambridge University Press.

Williams, R.S. Jr. and J.G. Ferrigno., 2002, Introduction. In: Satellite Image Atlas of Glaciers of the World. Glaciers of North America - Glaciers of Canada. Edited by: R.S. Williams, Jr. and Ferrigno, J.G. U.S. Geological Survey Professional Paper 1386-J.

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