Marco Bomio recalls that bright Sunday morning in June 2006 as if it were yesterday. Bomio, 59, a school principal and mountain guide, attended a religious service on a high mountain meadow to mark the founding of a local guide group.
“Suddenly we saw this immense cloud,” he said over coffee in a wood chalet typical of the Alpine village of Grindelwald. “Normally, it might have been snow. But in June?”
“Then we saw that it wasn’t snow,” he went on. “It was rock dust: Part of the mountain had come down.”
Grindelwald, population 3,800, lies in the foothills of a wall of Alpine peaks, rising to more than 3,900m. It is also home to two of Switzerland’s largest glaciers, the Upper and Lower Grindelwald Glaciers, which for millennia have snaked their way through Alpine gorges toward the town.
With global warming, the glaciers are melting. Once stretching to the edge of town, they now end high in the mountains. Moreover, their greenish glacial water is forming lakes. In summer, when the melting accelerates, floodwaters threaten the area. However, the avalanche witnessed by Bomio shows that the shrinking of the glaciers removes a kind of buttress supporting parts of the mountains, menacing the region with rock slides.
Grindelwald stands as a stark example of what is happening these days to Switzerland’s glaciers, and there are more than a hundred, large and small.
As the Lower Grindelwald Glacier shrank, its ice no longer buttressed the east wall of the Eiger, a 3,970m mountain that is part of the ring south of Grindelwald. Moreover, the warming reduces the effect of permafrost that once acted as a kind of glue, binding together the mass of the mountains.
On that day in 2006, a chunk of the Eiger amounting to about 688,099 m3 fell from the east face, causing the cloud of rock dust that startled Bomio and his friends.
Since 1997, Ruth Meier has run the Hotel Gletscherschlucht (the name means glacier gorge), with six rooms and 18 beds, at a point where water from the melting lower glacier runs out of a steep and narrow gorge. Well into the 20th century, the glacier extended clear through the gorge, which is about a kilometer long, and until about World War I, ice blocks were carved out of it for use in cooling in restaurants and kitchens as far afield as Paris. Where her hotel stands, a field kitchen once fed the workmen who hacked the ice.
Now a large lake of melted glacial water has formed above the gorge. To avoid potential flooding that would threaten the village below, Meier said, a US$15 million tunnel, almost 2km long, was completed in 2010 to channel excess water when the lake swells in the summer. Before that was done, she said, summer floodwaters regularly pushed gigantic ice blocks down the gorge.
“In July and August, it sounded like battle tanks coming down,” she said, sipping mineral water. “You could hear the stones rolling.”
Floodwaters forced their way through the narrowest parts of the gorge, about 10m across, “like water gushing from a garden hose,” she said.
Why build a hotel at such a delicate spot? “To be at the pulse,” Meier said. “We’re at the pulse of the eternal ice.”
Well, not so eternal any more. Over the past century or so, glaciers like those around Grindelwald have receded by about 425m, said Hans-Rudolf Keusen, a geologist whose company, Geotest, helped design the overflow tunnel.