White covers placed on the Rhône Glacier have been shown to reduce ice melting by approximately 60 percent in a 50,000 square meter area, according to a 2021 study led by glaciologist Matthias Huss, with researchers from the WSL, ETH Zurich, and the University of Fribourg. The study found that the covers preserved about 4 meters of ice per year, with the technique costing between 0.60 and 7.90 Swiss francs per cubic meter of ice preserved annually. The white textile protects the ice from excessive solar radiation, and several studies cited by Swiss researchers mention a reduction in melting of 50 to 70 percent. The Rhône glacier hosts the largest glacier coverage in Switzerland, equivalent to about seven football fields, and at the time of the study, 0.18 square kilometers of glacier were covered throughout the country, with the Rhône representing more than a quarter of that. However, this amounts to only 0.02 percent of the glacial surface in Switzerland. The technique is not a recent innovation; the first tests date back to 1993 on the Zugspitze in Bavaria, and in Switzerland, the first covers were placed in 2004. At the time of the study, nine sites used the covers, including the Rhône. In ski resorts, the covers can be profitable, as seen in the case of a nearly disappeared small glacier at Diavolezza in the Grisons, which was revived by preserving winter snow under a cover. Over the last decade, preserving 1 cubic meter of ice for one year has cost between 0.60 and 7.90 Swiss francs. At the national level, the technique has allowed the preservation of up to 350,000 cubic meters of ice per year. However, covering the entire glacial surface would require more than 1 billion Swiss francs annually, according to the same study. Matthias Huss emphasizes that the only way to truly limit the retreat of glaciers remains to reduce greenhouse gas emissions, as the covers would only slow down the retreat, with heavy consequences for the landscape and the environment. The Rhône is an exception, as in ski areas, the covers are removed every winter, while at the foot of the cave they were not. With the collapse of the glacial tongue, these covers had become difficult to secure and evacuate. On September 4, 2026, RTS reported that the Valais State Council had rejected the operator's appeal and that the cave had to close. The tunnel had been dug without permission in an area of national importance for alluvial plains protection. The attraction receives about 100,000 visitors per year. The operator had 30 days to appeal to the Valais Cantonal Court. The environmental service noted the removal of the covers during an inspection in August. The cantonal construction commission had required the removal of the covers and the cessation of work, then issued a decision in August 2025 to restore the site. On August 4, 2026, five associations, including Pro Natura, WWF, and Mountain Wilderness, delivered 10,066 signatures to the Valais chancellery. They also demand the removal of the covers that have sunk to the bottom of the glacial lake. The case goes beyond construction law. In 2022, the Valais environmental service noted that damaged textiles were drifting on the lake. Philipp Carlen estimated that the covers delay melting and present no danger to nature and humans, while Raimund Rodewald from the Swiss Foundation for Landscape Protection considered the measure to have no interest other than commercial in the face of the speed of the glacier's disappearance. The debate also concerns microplastics that degraded textile could release into the young waters of the Rhône. In mid-September, Canal9 reported that the cantonal commission had banned access to the cave, located in a dangerous area according to the authority. The operator, however, opposes these decisions and continues to exploit a remaining piece of ice detached from the glacier and covered with plastic covers. The removal is therefore not complete. The State told RTS that the covers not related to the cave had been removed and were waiting for their evacuation, but Canal9 images show pieces of plastic tangled among the rocks. The ice piece of the cave, however, remains under cover. In 2022, a record loss year for the Alps, the Rhône lost about 40 million cubic meters of ice, or more than 2.5 meters in thickness, and nearly 10 meters at the tongue where the cave is located. Matthias Huss was still taking melting measurements there on July 16, 2026.