Covering glacier ice: effective but expensive

Tarpaulins can be used to protect parts of glaciers from sunlight. In ski resorts, the resulting reduction in ice melt may make the measure economical at a local level. However, for financial reasons, it is not really feasible to cover large glaciers, as a study by glacier researchers from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), ETH Zurich and the University of Fribourg has demonstrated.

In recent decades, rising temperatures and summer heatwaves have seen most glaciers in the Swiss Alps melting at their fastest rates since records began, meaning that glacier ice has become a symbol of climate change. In many places, glaciers also play an economic role, especially where they are important for ski tourism. Glacier retreat here can jeopardise the viability and profitability of a glacier ski resort.

To address this problem, the first attempts to partially cover a glacier with a white tarpaulin began on the Zugspitze in southern Bavaria (Germany) in 1993. In recent years, the concept has also established itself in Switzerland as an efficient technique for reducing ice melt locally. "However, there were no studies looking at the costs involved and whether such measures could be carried out on a Switzerland-wide scale," says study leader Matthias Huss (WSL, ETH Zurich, University of Fribourg). In a paper published in the journal Cold Regions Science and Technology, he and his team have produced the first summary of experiences with glacier covers in Switzerland.

The first glacier in Switzerland to be protected with a white tarpaulin was the Gurschenfirn on the Gemsstock above Andermatt (canton of Uri), which has been covered from late spring through to autumn since 2004. This keeps the glacier thick enough for people to still ski down from the cable-car station. In the years since 2004, glaciers have been partially covered at seven other locations in the Swiss Alps at altitudes of between 2,250 and 3,250 m above sea level. A very small glacier on the Diavolezza (Pontresina, canton of Grisons) has even been 'brought back to life' after having virtually disappeared. Year by year, the snow that has fallen in winter is preserved under a fleece over the summer, so that the thickness of the ice has started to increase again.

As ice melt increases in ski areas due to climate change, the cost of the necessary covers is growing. The study found that the average cost for one cubic metre of artificially preserved glacier ice over the past decade was between CHF 0.60 and 7.90 per year, depending on the type of cover and its location on the glacier. These relatively high costs show how economically important glacier ice is. This is true of the Rhone Glacier, for example, where Switzerland's largest glacier cover (approximately 50,000 m²) aims to preserve a man-made ice grotto – a popular tourist attraction – for as long as possible.

Covering is not a silver bullet for preventing glacier retreat. While local covers can indeed be efficient and profitable, application on a larger scale, as a means of completely saving entire Alpine glaciers, is unlikely to be feasible or affordable. A hypothetical experiment calculated that it would cost over CHF 1 billion a year to cover all Swiss glaciers, and even this would only slow their decline, not stop it in the long term. Moreover, large swathes of glacier cover would have a major impact on the landscape and environment.