Scientists covered 200 square metres of a Swiss glacier with sheep’s wool; early tests found it protected the ice about as well as plastic sheets, but only 0.02% of Swiss glacier ice is covered

A sheep wool-covered snow protection test site is pictured during a press conference presenting the results of the “Keep It Wool” glacier protection experiment in Les Diablerets, Switzerland

A natural wool covering placed over 200 square metres of high-altitude Alpine ice has proved as effective at slowing summer melting as conventional synthetic tarpaulins, offering a possible biodegradable alternative to plastic sheets. Initial results from the “Keep It Wool” trial on the Tsanfleuron Glacier in western Switzerland show that prototype wool blankets protected snow and ice from heat about as well as plastic geotextiles. According to a Reuters report published on 3 September 2026, researchers found that the covers significantly slowed ice loss during the warmer summer months. However, project organisers and glaciologists stress that physical covers can only protect very small areas. Just about 0.02 per cent of Switzerland’s total glacier surface is currently covered with protective materials. This means the method is mainly useful for protecting ski areas or vulnerable infrastructure, rather than providing a wider solution to global warming.

Coverings shield only a minute fraction of Swiss ice:

Total Swiss Glacier Area: 99.98% Uncovered Area Under Protective Covers: 0.02%

Shepherds and scientists unite on high ice

The experiment at the Glacier 3000 resort near Les Diablerets was first proposed by four master’s students. It was later developed into a joint project involving the environmental organisation Summit Foundation, the University of Lausanne and the Swiss Glacier Monitoring Network (Glamos). In June, researchers placed two 100-square-metre wool blankets next to standard synthetic covers. This allowed them to compare the two materials directly in real Alpine conditions. The wool panels were made by Swiss textile company Fisolan. Measurements taken every two weeks throughout the summer showed that the wool blankets reduced ice loss by about the same amount as synthetic covers. These conventional covers usually cut local melting by 50 to 70 per cent. “I thought it wouldn’t be stable enough,” said Niklaus Zegeser of Fisolan, who said he was surprised by how well the natural fibre survived strong winds, heavy rain and freezing temperature changes. Eliot Gaffio, one of the student researchers, said the field team was relieved when the summer results arrived. “Now we have a result that we can see and even touch. It worked incredibly well,” Gaffio said.

Replacing plastic with discarded agricultural waste

For years, Alpine resorts in Switzerland, Austria and Italy have used large geotextile tarpaulins to cover important sections of glaciers during summer. The covers reflect sunlight and reduce heat transfer, but almost all conventional sheets are made from synthetic plastics such as polyethylene or PVC. Long exposure to strong ultraviolet light and wind can damage these plastic covers. As they break down, they can release tiny synthetic fibres into meltwater, streams and nearby soils. The search for a natural alternative led researchers to an agricultural byproduct that is widely available. Project manager Timothy Steiner said the team wanted to create a fully biodegradable cover while finding a useful purpose for Swiss sheep’s wool. Between 40 and 70 per cent of the wool is regularly thrown away or burned each year because there is little commercial demand for it. By turning an unused local material into a protective sheet for high-altitude ice, the project shows how agricultural waste could be reused in local climate adaptation efforts.

Extreme melt season highlights systemic limits

The trial took place as ice loss continues to accelerate across the European Alps. Unusually high summer temperatures caused winter snow reserves to disappear weeks earlier than normal, exposing darker glacier ice to sunlight much earlier in the season. Glacier retreat can also make high mountain slopes less stable, increasing the risk of landslides and rockfalls. This includes the major rockfall that damaged the Swiss village of Blatten in 2025. Melting glaciers can also affect water supplies further downstream during different seasons. Despite the success of the wool prototype, scientists warn that glacier blankets should not be seen as a solution to climate change. Glaciologists point out that protective covers are expensive to install, require significant labour to maintain and can only be used on small areas of high-value ice. Steiner and the scientific teams involved stressed that physical covers cannot replace rapid cuts in global greenhouse gas emissions. Sheep’s wool could help keep microplastics out of Alpine meltwater, but reducing fossil fuel use remains the only long-term way to slow the loss of the world’s glaciers and ice sheets.

Swiss scientists test wool to protect glaciers

A Reuters video report provides visual context on the 200-square-metre wool blankets installed on the Tsanfleuron Glacier alongside standard synthetic covers, with comments from members of the research team.