Destructive snow avalanches and climate change in the Swiss Alps

Snow avalanches are an important natural hazard in alpine areas. Especially settlements and traffic routes are threatened. A better understanding of the relations between avalanche occurrence and climate is necessary to deduce possible effects of climate changes on the avalanche hazard. This study investigates the relations of climatic conditions on avalanche release from 1947-1993 and extreme snowfall events from 1896-1993. The statistical evaluation of the meteorological data shows a long-term trend in temperature, but not in snow depth and extreme snowfall events. From the meteorological long-term time series at Davos (eastern Switzerland) we tried to model the corresponding avalanche activity from 1896-1946. The modelling of the avalanche activity was not successful because the extremely sparse distribution of extreme events prevented the establishment of a reliable statistical model. Looking at potential avalanche situations in terms of extreme weather situations it can be assumed that the climatic causes for severe avalanche periods have remained stable during the past 100 years and show no sign of change in the near future. However, the construction of defence structures in avalanche starting zones, improved zoning of hazardous areas and artificial avalanche release have reduced the probability of catastrophic events.