Mountaineering facing climate change : Geomorphological evolution of the routes, impacts on summer practice and decision support tools in the Mont Blanc massif ; L'alpinisme à l'épreuve du changement climatique : Évolution géomorphologique des itinéraires, impacts sur la pratique estivale et outils d'aide à la décision dans le massif du Mont Blanc

In the present context of climate change, this PhD in geography concerns the evolution of mountaineerings’ conditions of practice. This work uses a multidisciplinary approach and is structured on three different axes of research.First, we studied the evolution of mountaineering itineraries and their climbing parameters. Our results show that, even though adaptation works are realized, the accesses to high mountain huts are mainly affected by glacial shrinkage and are becoming more dangerous and technical. The assessment is similar for mountaineering routes. The comparison of 95 routes between the 1970s and their current condition showed that 26 itineraries are greatly modified and can hardly be climbed in Summer anymore. Because the itineraries have become more dangerous and technically more challenging – due to an increase in the number of processes affecting them - periods during which these itineraries can be climbed in good circumstances in Summer have tended to become less predictable and period of optimal circumstances have shifted toward Spring and Fall.This first findings led us to study, in a second axe of research, the way Alpine guides are affected by the evolution of mountaineering routes and how they adapt. Semi-structured interviews and a questionnaire survey, send to Alpine guides of the SNGM, shows that 97% are forced to adapt the way they work. This adaption is considered difficult to implement by half of the respondents, whose activity is centered on mountaineering. Five main strategies are implemented and lead Alpine guides to diversify towards activities outside the high mountain environment. This observation implies a redefinition of their work they are not always comfortable with.Finally, in a third axe of research, we focused on the assessment of mountaineers’ vulnerability and the acquisition and distribution of knowledge to encourage adaptive behaviors. Several reports and flash cards, based on the results of our two first axes of research and addressed to the mountain community in ...