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In A Nutshell
- Wool matched plastic in a first test. Two prototype wool blankets laid on about 2,100 square feet of the Tsanfleuron Glacier in June limited melting about as well as the standard synthetic covers, according to measurements taken every two weeks.
- The idea came from students. Four master’s students came up with the “Keep It Wool” project, led by the environmental group Summit Foundation and the University of Lausanne.
- It uses wool that would otherwise be thrown away. Project organizers say 40 to 70 percent of Swiss sheep’s wool is discarded each year.
- It will not save the glaciers. Protective covers shield only about 0.02 percent of Switzerland’s glacier surface, and the project’s backers say cutting emissions is the only meaningful long-term fix.
Every summer, crews at some Swiss ski areas and glacier attractions drag huge white sheets across the ice, a bit like tucking a bedspread over a mountain. The sheets slow the melting, but they are made of plastic, and they can shed tiny fibers into the meltwater.
This summer, four university students tested whether something Swiss farmers mostly throw away, sheep’s wool, could do the same job. After one season, the early answer appears to be yes. Here is what they did, why covering ice works at all, and why nobody involved thinks blankets can save the Alps’ glaciers.
What Did The Students Test?
Wool blankets side by side with the standard plastic covers.
The project, called “Keep It Wool,” is led by the Summit Foundation, a Swiss environmental group, and the University of Lausanne. In June, two prototype wool blankets made by the Swiss firm Fisolan were laid on about 200 square meters, roughly 2,100 square feet, of the Tsanfleuron Glacier in western Switzerland, Reuters reported. Through the summer, researchers compared them with a conventional synthetic cover.
Project manager TimothĂ©e Steiner said measurements taken every two weeks showed the wool limited melting as well as the synthetic covers. Even the manufacturer had doubts at first. “I thought it wouldn’t be stable enough,” said Niklaus Saegesser of Fisolan. Student Elliot Gaffiot was more direct: “Now we have a result we can see and even touch. It worked incredibly well.”
Why Does Covering Ice Slow The Melt?
A light-colored cover blocks much of the sun’s heat before it reaches the ice.
Bare ice and old snow absorb sunlight and warm up. Reflective covers bounce much of that light back and reduce how much heat the surface takes in. On the Rhone Glacier, where blankets protect a tourist ice cave, a Swiss glaciologist told AFP that they reduce melt by as much as 70 percent on the patch they cover. Wool may add a second layer of protection, since its fibers trap air and slow the flow of heat.
The problem with the usual covers is their material. Synthetic tarps are typically made from plastic and can shed microfibers into mountain meltwater, Reuters noted. Wool is natural and biodegradable, which is why the team wanted to know if it could hold up on the ice for a whole summer.
Could Blankets Save Switzerland’s Glaciers?
No, and the people behind the project say so themselves.
Only about 0.02 percent of Switzerland’s glacier surface is covered by protective sheets. Summit Foundation estimates those covers save roughly 300,000 cubic meters of snow a year, compared with nearly one billion cubic meters of glacier ice lost annually, according to a summary of the project. In 2022 alone, Swiss glaciers lost about 6 percent of their volume, a record at the time. Scientists say reducing greenhouse gas emissions remains the only meaningful long-term way to slow the loss.
The test also has limits. It covered one summer and two small patches, and the team has not yet published a full dataset. Nobody knows yet how wool holds up after several seasons of sun, rain and wind, or what it would cost at a larger scale.
What the students showed is narrower but still useful: where resorts already cover the ice, a local, biodegradable material may do the job without adding plastic to the mountains. The bedspread is still a bedspread. It just no longer has to be made of plastic.
