Compiled by Qimao
Marco Bormio still remembers that Sunday morning in June 2006.
Bormio, a school principal who also works part-time as a mountain guide, was at the time participating in a prayer ceremony on an alpine meadow with a newly formed local guiding group. "Suddenly, the wind picked up and clouds gathered," Bormio recalled. "Usually, that’s a sign of snowfall. But this was June!" Then they realized it wasn’t snow but a sky full of rock debris and dust: right before their eyes, part of the mountain had collapsed and was thundering down the slope.
At the foot of the mountain lies the Swiss town of Grindelwald. Situated at over 1,000 meters above sea level with a permanent population of just 3,800, the town is known for its serene and picturesque scenery, often hailed as one of the "most beautiful towns in the world." It is also home to two of Switzerland’s largest glaciers: the Upper Grindelwald Glacier and the Lower Grindelwald Glacier. Having migrated for thousands of years from the Arctic through Alpine valleys, they have gradually approached the town and now reside on the outskirts, nestled high in the Alpine peaks.
While the high-altitude glaciers bring hundreds of thousands of tourists to Grindelwald every year, they also quietly threaten the town’s tranquility. In summer, when temperatures rise, melting glacier snow can cause flooding; but more critically, what Bormio and others witnessed demonstrated that as glaciers melt, parts of the Alps could also collapse.
The precarious Alps
What collapsed before Bormio and the others was part of the Eiger, known as the "most dangerous mountain in Europe." The volume of the collapse totaled 900,000 cubic yards (approximately 688,000 cubic meters). Fortunately, it landed in an uninhabited area, with no injuries or building damage. Geologists analyzed that as the Lower Grindelwald Glacier accelerated its melting over recent decades, the eastern wall of the Eiger lost support, and meltwater seeping into the cracks between the rocks further widened these fissures.
The impact isn’t limited to glaciers but also affects permafrost — soil layers that remain frozen for three years or more. Permafrost accounts for 5–6% of the Alpine volume, twice that of glaciers, serving as a kind of “glue” for Alpine peaks. Since 2000, Swiss permafrost experts have closely monitored the Alps. According to their measurements, over the past century, the temperature of this permafrost has risen by 1–2 degrees Celsius. This means the “stickiness” of the permafrost has decreased compared to the past, and even a heavy rain could trigger widespread landslides.
Over the past century, glaciers in Grindelwald have receded by nearly 200 meters. And Grindelwald is not alone; hundreds of glaciers of varying sizes across Switzerland are facing similar situations, causing significant challenges to towns along the Alpine foothills. The summer heatwave of 2003 caused landslides on the iconic Matterhorn, blocking access routes and stranding dozens of climbers at the summit. A year before the Eiger collapse, in 2005, a large landslide on an Alpine meadow left the popular Stieregg Hotel “hanging” on the edge of a cliff, nearly resulting in tragedy. In May 2006, a landslide in the Swiss Alps sent rocks onto a highway, killing two people. Entering the second decade of the 21st century, videos of massive landslides in the Swiss Alps have become commonplace on video-sharing platforms.
Mountain guide Johann Kaufmann, a native of Grindelwald, grew up climbing and playing on the Eiger trails and knows the peak intimately. During a routine climb, he noticed a snow belt that, after melting in summer, seeped into rock crevices and caused erosion. The loosening rocks have also significantly changed local tourism and mountaineering activities: fewer people now attempt summits, and even when climbing higher altitudes, experts like Kaufmann recommend tackling the steeper north face in winter rather than the traditional west face in summer — although the north face is steeper and the route more challenging, it remains more stable under the protection of ice and snow.
“It’s not actually that dangerous,” Kaufmann said. “People can always adapt, but adaptation doesn’t change the facts — things really aren’t the same as they used to be.”
The hidden dangers beneath the lake
In the 1990s, the first cracks appeared in the Trift Glacier in the Bern region of central Switzerland. It then rapidly melted, and by 2002, it exploded from the top into tens of thousands of fragments, collapsing entirely. Because it was located in a valley, the melting glacial water did not cause a flood but instead accumulated into a glacial lake. Soon, Trift Lake became a new attraction, with hundreds of tourists now visiting daily via a suspension bridge over the lake to see the newborn lake and remnants of the glacier.
Wilfried Haeberli from the University of Zurich said at the European Geosciences Union annual meeting, “The rapid melting of glaciers is drastically altering the landscape of the Alps.” Haeberli and his colleagues developed a computer model to predict the volume of ice melt based on past decade’s geomorphological changes and future climate trends. They predict that in the foreseeable future, 500 to 600 lakes like Trift Lake will form in Switzerland’s high mountain regions.
In 1997, Ruth Meier opened a guesthouse called “Glacier Gorge,” situated right next to a narrow canyon where glacial meltwater flowed. In the early 20th century, the glacier still occupied this approximately one-kilometer-long canyon. By World War I, people began cutting ice from the glacier for cooling and preservation in hotels and kitchens, even attracting renowned Parisian hotels. Meier’s small guesthouse was built where the ice was once harvested.
But now, there is no glacier in the canyon; in fact, a new glacial lake has formed upstream. The lake is calm and clear, offering a unique charm at the foot of the high mountains. “These lakes may seem harmless,” said another geologist, Hans Rudolf Kuhn. For now, smaller lakes will eventually disappear as their riverbeds are unstable and prone to merging with other glacial melt rivers. “But we need to think long-term. If it’s a large basin capable of holding 8–10 million cubic meters of water, the lake will keep growing, and that becomes a major hazard.”
The hazard refers to flooding. In hot summer weather, glacier melt accelerates, producing more glacial water, which may cause lakes to overflow. The force of the floodwaters can also push massive chunks of ice downhill.
“It’s most common in July and August. It sounds like tanks rolling by, rumbling,” she said. “You can hear the rocks coming down.” The narrowest part of the canyon is less than 10 meters wide, and during floods, the situation is completely out of control and terrifying. In 2010, the Swiss spent $15 million to build a spillway to protect downstream villages from being washed away. According to Haeberli, Switzerland has many such spillways.
Particularly dangerous is the Aletsch Glacier, the largest in the Alps, beneath which lies a deep basin that will soon be filled with glacial water. The basin is flanked by steep cliffs. Haeberli fears that when the glacier melts, the unsupported cliffs may collapse into the glacial lake, generating massive waves. This could trigger catastrophic flooding, potentially submerging two villages.
Residents living near the Plaine Morte Glacier are also worried, as a new lake is gradually forming beneath the melting glacier tongue. “We can’t let these lakes develop unchecked,” Haeberli warned. To prevent future dangers, it’s best to install pressure sensors on the ground and cables on the lake surface so people can know when the water is about to overflow and respond promptly.
Disaster-touring visitors
If the area at the foot of the glacier is so dangerous, why did Ms. Meier choose to build her guesthouse in such a risky location? “You’ve got to occupy the strategic spot,” Meier replied. “We’re standing right on the lifeline of eternal ice.” Yes, although eternal ice is no longer eternal, and there may be many downsides downstream of the lakes, these glacial lakes themselves attract more tourists. “Actually, more people come to see the glaciers now than before,” Haeberli said.
In fact, the Eiger landslide disaster also piqued many people’s interest. For years, various videos of Alpine landslides have circulated online, with their spectacular scenes and thrilling sounds hard to forget. In 2007, the Eiger experienced another major landslide, with nearly 500,000 cubic meters of mountain collapsing, sending a cloud of dust over the entire Grindelwald town. This drew countless onlookers, with many even making special trips to witness the disaster. “My son counted — 22 helicopters flew in that day, carrying all kinds of people to see our landslide,” said Hansrudi Beyerag, who runs a temporary campsite at the foot of the Eiger. “You know, that’s just a small part of the Eiger.”
Tourism has long since replaced agriculture as the main economic driver of Grindelwald. The first visitors were British aristocrats who discovered the area’s charm in the 18th century; later came people from all over Europe. Today, around 800,000 Europeans visit the town for vacation each year. Recently, travelers from the Americas and Asia have also been rapidly increasing, eager to undergo some training and then hike from the town center all the way to the summit of the Jungfrau, known as the “Top of Europe.”
Generally, people don’t want popular tourist spots to change, but Grindelwald is different. Haussvis, a 45-year-old ski instructor, believes that changes in the landscape are not threats but opportunities. “You have to adapt,” he said. “The risks here aren’t any higher than in other parts of the Alps, and locals are used to the majesty of the mountains — that’s nature.”
Mountain guides like Bormio can even benefit from glacier melting: they organize so-called “warming tours,” using real-life changes in the area to give visitors an eye-opening environmental lesson. “That way, you can witness the real changes, feel them, and learn about our response measures,” Haussvis said.
Beyond that, there are more practical benefits. In Switzerland, the lakes formed by the country’s most famous glaciers — Aletsch, Görner, Plaine Morte, Otemma, Corbassière, and Gauli — have the potential to rank among the world’s top 20 largest reservoirs. “These new lakes can be utilized for hydropower generation,” Haeberli explained. In Switzerland, lower-altitude lakes may disappear within a few years, and these newly formed lakes can fill the gap. Currently, scientists have plans to harness the lakes formed by the melting of Corbassière, Gauli, and Trift glaciers to build a new hydropower station. It is predicted that the annual power generation of this station could reach 500 megawatts. Haeberli stated that around forty lakes will “join” the energy sector.