Coastal Response to Physical Setting and Variable Forcing Across the Canadian Arctic
Donald L Forbes1,2, Nicole J Couture
3, Trevor Bell
2, Thomas S James
4, Dustin Whalen
1, Gavin K. Manson
5 and Benjamin A Bagnall
2, (1)Geological Survey of Canada, Dartmouth, NS, Canada, (2)Memorial University of Newfoundland, Department of Geography, St. John's, NL, Canada, (3)Geological Survey of Canada, Natural Resources Canada, Ottawa, ON, Canada, (4)Geological Survey of Canada, Natural Resources Canada, Sidney, BC, Canada, (5)Geological Survey of Canada, Natural Resources Canada, Dartmouth, NS, Canada
Contact First Author: Donald L Forbes; sokovoli@gmail.com
Previously Published Material: This is an invited overview paper that draws on many years of experience across the Canadian Arctic and inevitably some of the ideas have been previously reported in contributions such as Forbes, D.L. and Hansom, J.D. 2012. Polar coasts. In: Treatise on Estuarine and Coastal Science, vol. 3, 245-283, Academic Press, Waltham. In addition, the results related to RSL change in northern Canada are drawn from a recently published Geological Survey of Canada Open File, cited in the abstract. The presentation in this form as a synthesis of coastal sensitivity to climate change and other forcing across the Canadian Arctic, incorporating the latest RSL projections and unpublished field results, is original and not under review or accepted elsewhere.
English Abstract:
Canada’s northern coasts comprise over 180 000 km of shoreline extending across 80° of longitude (Beaufort Sea to Labrador Sea) and >30° of latitude (James Bay to Lincoln Sea). Large environmental gradients in temperature, ground ice, sea ice, sea-level trend, storm climate and other factors across this vast area interact with a complex mosaic of geology and geography to produce a wide range of coastal features and sensitivity to environmental change, an understanding of which is needed to minimize negative impacts and challenges to sustainability. Relative sea-level (RSL) trends and projections, available for 22 sites across northern Canada (1), range from rapidly falling to rapidly rising RSL. Trends and projections are affected by global mean sea-level rise, glacial isostatic adjustment (GIA), gravitational fingerprinting, and dynamic oceanography. GIA dominates regional variability of RSL in northern Canada. Some areas such as the transgressive breached-lake and ice-rich permafrost shores of the Beaufort Sea already exhibit rapid change. Rising temperatures, promoting thermal abrasion, and expanding open-water, enabling more energetic waves, promote rapid and locally accelerated coastal retreat in this region. Where sediment supply is high, shoreline progradation can counteract the effects of rising sea level. Elsewhere, stable or falling sea levels against resistant rock shorelines limit rates of coastal change, except where rapid emergence (forced regression) is ongoing. Even in such areas, expanding open water and increased wave activity can promote unexpectedly rapid coastal realignment, as at Arviat and Hall Beach, Nunavut. Ice-locked, low-relief, coasts on unlithified formations in the Sverdrup Basin are primed for rapid wave reworking should open water become more extensive, but this area may be among the last to see a reduction in sea ice.1James et al., 2014, http://ftp2.cits.rncan.gc.ca/pub/geott/ess_pubs/295/295574/of_7737.pdf
