Time trends in avalanche activity and links with climatic drivers in the French Alps
Résumé
Previous studies described growing evidences or recent climate fluctuations in the alpine scale. A net warming is now well established since the end of the Little Ice Age, accelerated since 1985. One of the most direct impacts is a snow cover decrease at low and mid elevations, both in terms of local snow depth and snow cover duration, but also an increased variability, especially for winter temperatures. To study climatic variations in mountains area, snow avalanches are currently extremely rarely used for this purpose because their response to climatic fluctuations remains largely unknown. It is mainly due to the difficulty to assess its climatic control. Indeed, avalanche release has not a linear response to snowpack evolution ; moreover, controlling factor, such as temperature, can increase or decrease the snowpack stability. An other major limitation for the avalanche activity study is the difficulty of collecting data, especially during winter. Understanding the links between climate and avalanche activity is important: from an operational point of view (forecasting and risk management in mountains area) ; from a more fundamental interest: as natural avalanche activity is directly controlled by the quantity and quality of available snow cover, could it be therefore an attractive indicator of climate change ?