Climate Change and Erosion Processes in Mountain Regions of Western Canada

Abstract

Five mountain regions of Western Canada display distinctive hydrologic regimes and can be expected to respond dif- ferently to climatic change. A review of the extreme boundary conditions for climate change by A.D. 2050 for western Canada between 500 and 600 North as simulated by global climatic models indicates that all predict warming and the majority predict increased precipita- tion. Implications of these predicted changes for erosion processes are shown to depend heavily on the lagged response to climate change of glacier, permafrost, vegetation, and sediment systems. While runoff and available water resources will respond to climate change on an annual basis, glacier, permafrost, and vegetation responses are measured in decades to centuries and sediment systems take centuries to millennia to respond regionally. The three sources of uncertainty (the spatial variability of mountain systems, the range of predicted climate change scenarios, and the variable lag times of environmental systems to climate change) lead to qualitative estimates and predictions of tendencies rather than to confident assertions about geomorphic impacts of climate change. If principles of sustainable development are to be applied to mountain systems over the next few decades, an improved understanding of climate-erosion relationships is urgently needed, in particular the relationship between relevant meteorological events and climate sensitive processes.