Blanket for ice cover? Scientists wraps Swiss glacier with sheep’s wool to protect it from melting; early tests found it protected the ice about as well as plastic sheets

High above the Swiss resort town of Les Diablerets, on a slab of ice most people will never set foot on, a strange experiment has been quietly playing out all summer. Rather than the usual sheets of white plastic that ski resorts drape over glaciers to slow the melt, a patch of the Tsanfleuron Glacier has been tucked in under something far more old-fashioned: sheep's wool. And, somewhat to everyone's surprise, the wool held its own.

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An Odd Idea That Started With Four Students

The project didn't come out of a corporate lab or a government climate ministry. It began as a thesis idea dreamed up by four master's students, who wondered whether a natural, biodegradable material could do the same job as the synthetic tarps that have become a familiar, if controversial, sight on European glaciers each summer.


That idea eventually grew into a full-blown field trial, backed by the University of Lausanne, the Swiss Glacier Monitoring Network (Glamos), and the Summit Foundation, a nonprofit focused on environmental research in the Alps. Local textile maker Fisolan supplied the wool panels themselves.

This past June, the team hauled two large wool blankets, 100 square metres each, up onto the glacier and laid them right beside standard plastic covers, the kind resorts have relied on for years. Then they waited, checking in on both materials roughly every two weeks as the summer heat set in.

Plastic's Long-Time Job, Done Differently

Glacier covers work by bouncing sunlight back off the ice and cutting down how much heat actually reaches the surface underneath. It's a trick ski resorts across Switzerland, Austria and Italy have leaned on for years to protect slopes, lift infrastructure and the occasional glacier cave attraction from disappearing mid-season.

The catch is the material itself. Most covers are made from polyethylene or PVC, and years of brutal UV exposure and wind eventually break the plastic down. What's left behind isn't nothing, it's microplastic, and a lot of it ends up in glacial meltwater, then in mountain streams, then in soil far below.

Wool, in theory, sidesteps that entirely. It breaks down naturally instead of shredding into synthetic fibers.

By the end of summer, the numbers told a clear story: the wool blankets cut ice loss by roughly the same margin as their plastic counterparts, somewhere in the neighborhood of 50 to 70 percent less melting compared to bare, uncovered ice.

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Fisolan's Niklaus Zegeser admitted he went into the project doubtful the material would hold together at all. He'd expected wind and rain to tear it apart. Instead, it weathered the season intact. Student researcher Eliot Gaffio put it more simply, saying the team finally had something they could see and touch with their own hands.

Turning Waste Into a Climate Tool

There's a second story buried in this trial, and it's about Swiss sheep farming, not glaciers. Somewhere between 40 and 70 percent of the wool sheared from Swiss flocks each year simply goes to waste, burned or discarded, because there's barely a market left for it. Project lead Timothy Steiner has been open about the fact that part of the motivation here was practical: find a real use for a material the country already produces in huge quantities and currently throws away.

If wool blankets do eventually replace plastic ones on a wider scale, it would mean turning an agricultural leftover into a genuine climate adaptation tool — a rare case where two unrelated problems might share one solution.

A Band-Aid, Not a Cure

Nobody involved in the project is pretending this fixes anything at scale. Covering glaciers, wool or plastic, is expensive, labor-intensive, and only realistic for small, high-value patches of ice near ski lifts or fragile infrastructure. Right now, protective covers of any kind shield only about 0.02 percent of Switzerland's total glacier surface, a rounding error against the country's shrinking ice fields.

And the backdrop makes that limitation impossible to ignore. This summer, unusually high temperatures across the Alps melted away winter snow cover far earlier than normal, exposing darker, more heat-absorbing ice to the sun for weeks longer than usual. Faster-retreating glaciers also destabilize mountain slopes, raising landslide risk, a danger starkly illustrated by the catastrophic rockfall that buried much of the Swiss village of Blatten in 2025. Downstream, shrinking glaciers threaten to disrupt water supplies that entire valleys depend on through the year.

Steiner and his colleagues are blunt about where wool fits into that picture: nowhere near the center of it. It might spare a ski slope. It might keep microplastics out of alpine streams. What it cannot do is replace the one thing scientists say actually slows glacier loss, cutting fossil fuel emissions, and doing it fast.