A summer of extreme melting on the Arolla glacier in Valais

Margot Hofmann spent the summer on a glacier at 2,700 metres above Arolla, in Valais. A doctoral researcher at the University of Lausanne, she says she watched the ice melt with her own eyes, week after week.

A crate of research equipment left on the ice ends up raised 20 to 30 centimetres above the surrounding surface after just a few days, because it shields the ice beneath it from the sun. All around, the ice melts much faster. In July, to install sensors, the team had to dig at the same spot again and again: every four or five days, the layer of ice reached previously had already melted away.

The landscape she describes is made of rock, debris, dark ice, crevasses and a great deal of meltwater, which stays on the surface until it finds a crack. Beneath the glacier runs a network of rivers and channels that carry sediment eroded by the ice: the more the glacier melts, the more its bed is eroded, and the more sediment is carried downstream. This link between melting and sediment transport is exactly what Hofmann's research focuses on.

Beyond the data, the researcher also speaks of the strain of continuing to study an environment that is disappearing. "Mi deprime, a dire il vero" ("It genuinely gets me down"), she admits: she loved glaciers even before she took up research. Finding a glacier in Switzerland that is large and accessible enough is getting harder: many have become unstable or too remote, to the point that even some mountaineers now avoid them.

Dams may become harder to fill

Stuart Lane, a professor at the Faculty of Geosciences and Environment of the University of Lausanne, places the phenomenon in a broader context. Two effects combine: the ice melts for longer and more intensely, while the snow that used to remain on glaciers at the end of summer, turning into new ice over winter, is now often already gone by the end of September.

The consequences also extend to hydropower. Today, glaciers still help fill reservoirs when winters are low on snow, acting as a kind of insurance against water shortages. As glaciers shrink, this buffer will disappear, and water availability from one year to the next will depend almost entirely on winter precipitation. In a future without glaciers, a dry winter could translate directly into reservoirs left unfilled.

Several projects, at the federal level and within the hydropower sector, are already trying to soften this variability: on the Gorner glacier, a new dam is planned specifically to reduce these year-to-year swings in available water. According to Lane, artificially covering glaciers to slow their melt is not a solution that can work on a large scale, and it would in any case prevent winter snow from turning into new ice.

What remains unclear is who will bear the cost of this adaptation, and how energy and water supply security will be guaranteed in regions that will depend increasingly on the weather of each individual winter.