Environmental degradation is a threat that permeates into the beautiful mountain regions of the world, the Himalayas and the European Alps. Similar processes can be observed in the Andes and in Northern Africa. In the Alps, despite a wide range of measures taken during the last century to cope with the destructive forces of water, the Alps face new signs of environ - mental degradation. With this statement from 1989, the Himalayan Adventure Trust (renamed the Himalayan Environment Trust in 1990), which brings together renowned mountaineers, highlighted the progressive degradation of mountain environments across the globe, not just in the Himalayas, drawing particular attention to the problems of soil and water pollution, deforestation and the widespread presence of waste. Drawing on scientific literature on environmental issues in mountain areas over recent decades, and in line with the research project «La mondialisation des Alpes, du paysage à l’environnement» (carried out from 2022 to 2026 by the Department of Contemporary History at the University of Fribourg, with the support of the Swiss National Science Foundation), the conference ‘The Environment at the Summit’ will examine the gradual process by which the issue of environmental protection has taken hold in various mountain ranges worldwide, from the late 18th to the early 21st century (setting 2022 as the final threshold, corresponding to the International Year of Mountains). The aim is to encourage a decentralisation of perspectives in order to highlight the diversity of trajectories and also the possible circulation, both direct and indirect, of knowledge, materials, practices and individuals across the various mountain ranges. By taking mountainee - ring as a lens through which to interpret history – a relationship with the environment that has, moreover, received little attention in historical scholarship – we have sought to explore three areas of analysis: its actors (individually and collectively) and their concerns; its representa - tions and how these define the issues at stake; and the obstacles they face in putting forward their ideas.