Climate Change: Numerical Modelling of Sedimentation and Coastal Processes, Eastern Canadian Arctic^‡

‡ PALE contribution 14; Geological Survey of Canada contribution 40293.

Abstract

We use three sequential “water-sediment transport” numerical models to evaluate changes in fluvial sediment outputs for two near-future contrasting climate-change scenarios (warmer summers or warmer and moister winters) for the eastern Canadian Arctic. Our integrated model generates values for deposition into a fiord basin. The effects of climate warming are imposed on 200-yr fluctuations in relative sea level (base level) that in turn have a long-term forcing associated with late Quaternary glacial unloading. Thus some areas are submerging (around the periphery of the former ice sheet) and others are emerging (inland at the heads of fiords). Small, short-term changes in sea level may involve meltwater supply to the world ocean from the melting of glaciers and ice sheets, and sea water expansion with a warming ocean. Alternatively, large ice sheets may also thicken over the short term (200 yr), thereby withdrawing water from the global hydrological cycle. Both climate scenarios result in an increased sediment flux over the next 200 yr. However, warmer summers will have the largest impact by (1) causing ice caps to melt, (2) inducing more expansive and turbid river plumes, (3) increasing progradation of the coastline into the sea, (4) raising relative sea level, and by (5) increasing the number and size of turbidity currents generated off river mouths. Warmer and moister winters that may lead to deviations from these impacts include (1) growth of ice caps, (2) fall of relative sea level, (3) stability of coastlines as increased sediment delivery keeps pace with changes in regional relative sea level, and (4) fewer basin turbidity currents, as more of the bedload is trapped on top of sandur surfaces.