“Since 1980 it has been very rapid,” Keusen said. “In the past 30 years the average temperature in the Alps has risen by one-and-a-half degrees.”
For Alpine towns like Grindelwald, the changes are challenging. As the glaciers recede, they leave masses of rock and sediment — moraines — on their edges. In 2011, rock and snow came down on the upper glacier, as sides of a mountain became unstable without the supporting pressure of the ice. A year before the Eiger collapsed, in 2005, a section of a high Alpine meadow fell, leaving a popular restaurant, the Stieregg, hanging precariously on the edge. Meier’s mother-in-law recalled herding sheep there as a girl.
Tourism long ago supplanted agriculture as the driver of the local economy. Every year, about 800,000 visitors from all over Europe, but also from the US and increasingly Asia, board trains to climb from the town center to the Jungfraujoch, a saddle between two peaks more than 3,960m high known as “the top of Europe,” to enjoy the view.
The first tourists, English aristocrats, came in the 18th century. The first hotel opened in 1820; the first skiers came in 1891.
Tourism now amounts to “more than 80 percent of the economy,” said Bruno Hauswirth, a marketing expert who manages the local tourism agency.
“It’s not just tourism; it’s a cross section,’’ he said. ”Construction, financial services, retail.’’
Outside his office, backhoes were excavating for a US$30 million shopping area in the village center.
Hauswirth, 45, who skied and taught skiing in North America, Japan and New Zealand before returning to his native Grindelwald, sees the changes in the mountains as an opportunity, not just as a threat.
“You learn to live with it,” he said.
The risks “are no more than in other areas of the Alps,” he said, adding: “People here are used to living with the mountains; it’s natural.”
Some tour guides like Bomio are profiting from the results of global warming, organizing “warming tours” to explain its effects using local developments as examples.
“Here you can visualize it; you can see it and feel it,” Hauswirth said. “You can see how we are reacting to it.”
The gorge overflow tunnel is not the only reaction. Hiking trails are being moved to avoid areas at risk, said Herbert Zurbrugg, Grindelwald’s town secretary. Across the mountains, Zurbrugg said, the authorities are installing radar devices to track movements in the landscape so that the few tourist destinations, like campsites, that are near glaciers can be evacuated if necessary.
“I think we can say we have the situation under control,” Zurbrugg said. “There is no fear.”
Most measures taken, to control the flow of meltwater or to monitor regions surrounding the glaciers, are well outside the inhabited parts of town, he said.
“We are in a fortunate situation,” he added.
He paused, then said: “Yet, you never know.”