Glaciers’ role as water resource in the Swiss Alps

In high-mountain environments such as the European Alps, glaciers are an important component of the water cycle. With ongoing climate change, this role seems in jeopardy though: glaciers in Switzerland, for example, have lost more than 30% of their volume since the year 2000, and future projections indicate a future with ice-free landscapes if society was to fail in taking immediate and stringent climate action.In this contribution, the role of glaciers as water resource will be reviewed. By taking the Swiss Alps as an example, their contribution to regional water supplies and usage will be quantified. A focus will be on the glaciers’ role in providing water during dry periods, as well as the relevance of glacier melt in the context of hydropower production.Based on both extended glaciological measurements collected in the frame of the Glacier Monitoring Switzerland (GLAMOS) program and daily glacier melt data retrieved through automated methods, we will for example quantify the meltwater contribution that glaciers had in the extremely hot summer 2022. The year saw a record-high 6% glacier volume loss and we show that individual heat waves contributed over-proportionally to this amount: 35% of the total summer ice loss, for example, occurred in the 25 hottest days, delivering a water amount that corresponds to 56% of the total summer melt seen on average for the past decade.Such phases of extreme melt can also be challenging for water resource management. In high-alpine rivers, where annual glacier contributions to streamflow were up to 80% in 2022, existing hydropower infrastructure can for example be overwhelmed. For a country that sees some 2.1kWh of hydro-electricity being produced for every cubic meter of glacier melt, this raises questions about future management strategies, and calls for robust projections of future streamflow.