a1 Département de Biologie and Centre d'Études Nordiques, Université Laval, Sainte-Foy, Québec G1K 7P4, Canada
a2 CSIRO Marine Research, GPO Box 1538, Hobart, Tasmania 7001, Australia
a3 Geophysical Institute, University of Alaska, PO Box 757320 Fairbanks, AK 99775-7320, USA
Early explorers in the Canadian high Arctic described a fringe of thick, landfast ice along the 500-km northern coast of Ellesmere Island. This article shows from analyses of historical records, aerial photographs, and satellite imagery (ERS-1, SPOT, RADARSAT-1) that this ancient ice feature (‘Ellesmere Ice Shelf’) underwent a 90% reduction in area during the course of the twentieth century. In addition, hydrographic profiles in Disraeli Fiord (83°N, 74°W) suggest that the ice-shelf remnant that presently dams the fiord (Ward Hunt Ice Shelf) decreased in thickness by 13 m (27%) from 1967 to 1999. Mean annual air temperatures at nearby Alert station showed a significant warming trend during the last two decades of this period, and a significant decline in the number of freezing degree days per annum. The ice-dammed fiord provides a stratified physical and biological environment (epishelf lake) of a type that is otherwise restricted to Antarctica. Extensive meltwater lakes occur on the surface of the ice shelf and support a unique microbial food web. The major contraction of these ice–water habitats foreshadows a much broader loss of marine cryo-ecosystems that will accompany future wanning in the high Arctic.
(Received July 2000)