In Switzerland, high mountain areas are highly developed for tourism. Mountain tourism is mainly based on outdoor activities such as hiking, mountaineering, or skiing. These activities depend on the environment, and climate change is nowadays changing the basis for them. For example, the reduction of snow availability during the winter season is a challenge for ski tourism, while glacier retreat challenges the future of glacier tourism and alpinism during the summer season. The former challenges raise the issue of destination adaptation to climate risks, especially if the destination relies on vulnerable activities. In this context, summer glacier ski - broadly defined as skiing on glaciers from May to the end of October - appears to be particularly vulnerable to both glacier retreat and reductions in summer snowfall at high altitudes. While some research has been done on this particular activity in Austria, little light has been shed on the two last remaining summer glacier ski resorts in Switzerland: Saas-Fee and Zermatt. Accordingly, the aim of this presentation is to share the first results of a research project that aims to better understand adaptations to climate change impacts on summer glacier skiing in Saas-Fee and Zermatt. As glacier summer ski resorts involve multiple stakeholders interacting in complex ways with each other and their environment, the project aims to develop a systemic framework for adaptation. For this reason, semi-structured interviews were conducted with tourism stakeholders of the two destinations (n=10) and with skiers and managers of sports teams (n=14), who appear to be the main customers of the activity. Preliminary results show that climate change raises issues on both the demand and supply sides. The impact of climate change on snow and glacier conditions leads to an increase in operating costs, the risk of closure during the summer, leading to an increase in uncertainty about the ability to operate. This affects the demand side, in particular professional skiers who have to book and pre-pay for ski runs, with the uncertainty that the glacier will be available at the time and that they will be able to complete their summer training. Accordingly, the demand side tends to develop substitution behaviour by travelling to the southern hemisphere or using artificial ski domes to increase their likelihood of completing their training. Findings are expanded and discussed to identify interrelationships between the different stakeholders involved.