ORIGINAL G. K. Manson Æ S. M. Solomon Æ D. L. Forbes D. E. Atkinson Æ M. Craymer Spatial variability of factors influencing coastal change in the Western Canadian Arctic Received: 7 November 2003 / Accepted: 2 August 2004 / Published online: 18 December 2004 Ó Springer-Verlag 2004 Abstract Coastal change in the western Canadian Arctic is influenced by coastal morphology, relative sea-level trend and sea-ice and storm climates. The spatial vari- ability of these factors tends to follow general east–west trends suggesting similar trends in coastal erosion haz- ard, processes and rates of coastal change. The spatial variability in the causes of coastal change is examined in the communities of Tuktoyaktuk, Sachs Harbour, Hol- man and Kugluktuk. Abbreviations RSL: Relative sea level Æ GPS: Global positioning system Æ CGPS: Continuous global positioning system Introduction Recent climate modelling indicates that high-latitude regions in the northern hemisphere will be more affected by greenhouse-induced climate change than areas at lower latitudes (Ra¨isa¨nen 2001). Of specific relevance to coastal areas, sea ice is expected to decrease (Johannssen et al. 2002), allowing a longer period for storms to interact with shorelines; summer temperatures are ex- pected to increase (Johannssen et al. 2002), allowing increased melting of ice-bonded sediments in coastal cliffs; a small increase in storm frequency may occur (Lambert 1995) with potential increased storm impacts, and global eustatic sea-level rise is expected to accelerate (Church et al. 2001). Shaw et al. (1998) developed an index of sensitivity to sea-level rise for the entire Canadian coastline. Defined as the likelihood that physical changes will result from accelerated sea-level rise, the index is based on coastal relief, lithology, sea-level trend, wave climate, rate of coastal retreat, and tidal range. In the western Canadian Arctic, the westernmost communities of Tuktoyaktuk and Sachs Harbour are ranked as highly sensitive, whereas the more eastern communities of Holman and Kugluktuk are ranked low (Fig. 1). This suggests the existence of west–east gradients in coastal processes and morphology. This paper presents early results from ongoing pro- jects in the western Canadian Arctic, with particular attention to the spatial variability in coastal forcing and response inferred from weekly ice charts, tide-gauge data, measured wind speeds and directions, observed and predicted vertical crustal motion, and observations of coastal geology and morphology. We focus on coastal conditions in the vicinity of three communities in the Northwest Territories (Tuktoyaktuk, Sachs Harbour, Holman) and one in western Nunavut (Kugluktuk [formerly Coppermine]). Coastal morphology and features Tuktoyaktuk The community of Tuktoyaktuk (Fig. 2) is located on the Kugmallit Plain, an area of low relief broken by thermokarst depressions and involuted hills and pingos up to almost 50 m high (Rampton 1988). Thick Pleis- tocene fine to medium sands, likely of glaciofluvial origin, underlie most surface units at depth throughout the area. Beds of coarse and pebbly sands are present, as are occasional silty beds. A hummocky, silty clay diamicton consisting of till or colluvium derived from till overlies the glaciofluvial sands in many locations G. K. Manson (&) Æ S. M. Solomon Æ D. L. Forbes D. E. Atkinson Geological Survey of Canada, PO Box 1006, Dartmouth, NS, Canada, B2Y 4A2 E-mail: gmanson@nrcan.gc.ca Tel.: +1-902-4263144 Fax: +1-902-4264104 M. Craymer Geodetic Survey Division, 615 Booth Street, Ottawa, ON, Canada, K1A 0E9 Geo-Mar Lett (2005) 25: 138–145 DOI 10.1007/s00367-004-0195-9