Impacts of climate change on debris flow occurrence in the cordillera of western canada and the european alps

Abstract

In spite of a general agreement on present climate trends, actual impacts on terrestrial systems are still very debated. Evidence is mounting that climate change is affecting the stability of slopes, although the full extent, time, and magnitude of the response remain uncertain, in part because climate is only one of the factors contributing to slope instability. Moreover, at the regional and local scale climate change patterns can be very different. Mountain environment seems to respond promptly to climate warming, in part because of the presence of the cryosphere. The present paper contributes to discussions within the scientific community by discussing controls on debris flow occurrence in the Cordillera of western Canada and the European Alps. Several debris flow case studies illustrate how cryosphere degradation can play a significant role in debris flow occurrence in glacial and periglacial margins, both on a short and on a long time span. Processes responsible for debris flow development under a warming climate include rock falls and rockslides induced by glacier debuttressing, thaw of alpine permafrost, sudden draining of glacial lakes, and exposure of unconsolidated, unvegetated, and commonly ice-cored sediments due to glacier recession.