00:00Franziska von Bergen is mowing the lawn in front of her house in Switzerland's Bernese Oberland one last time.
00:10Her family has lived here in the village of Gutanen for generations.
00:16But the moving boxes are already packed.
00:19She's been forced to leave.
00:21Her home is threatened by flows of debris known as murgänge, rock slides from the surrounding mountains.
00:30These images taken from a surveillance camera in Gutanen reveal the danger.
00:38You couldn't actually see much because of all the dust and mist in the air.
00:42The weather was bad.
00:44It always is when things like this happen.
00:47It was just before dark and it was eerie.
00:50You could only hear the roar of the water, the rocks being pushed along the creek bed.
00:56The smell of the earth was everywhere.
01:03Her house stands alongside the Are River.
01:06There was once a small riverbed here.
01:09Now some 20 metres of stone and debris have built up.
01:13The next flood could hit the houses too.
01:19Gutanen would actually make a picture-perfect postcard.
01:22Nestled amongst tall mountains, the way Switzerland likes to present itself to tourists.
01:28A paradise for bikers, hikers and mountaineers.
01:33The nearby Grimsel Pass offers day-trippers an alpine panorama.
01:38Werner Schleppi has no time to take in the scenery though.
01:42Gutanen's village mayor shows us what's posing the threat to his community.
01:52It's these couloirs above the treeline, typically filled with rocks and ice.
01:58With temperatures rising though, they've begun to thaw out.
02:04With the thawing of the permafrost and the warming that's undoubtedly taking place,
02:09collapses are coming.
02:11The brittle rock face is loose.
02:15If it's warm over a long period and the zero-degree isotherm line rises to 4,000 metres or higher
02:21for two to three weeks in summer, this area becomes dangerous.
02:32Dangerous like it was here in Switzerland in summer of 2024.
02:37Following heavy rains, a debris flow swept through a village in the Grisons, destroying key roads.
02:44A week later, after torrential downpours, ones hit neighbouring Ticino
02:50and the Saas Valley in the Valais.
02:54Swiss tourist destinations are facing the consequences of increasingly hot summers,
02:59paired with significant rainfall.
03:05Markus Wies is an engineer responsible for protecting the Bernese Oberland.
03:10Here in Brienz, a debris flow even breached a 15-metre high safety barrier.
03:19In mid-August, masses of water swept through the village, taking everything with them, including trees.
03:29The local authorities are in regular dialogue with Brienz residents
03:33and don't shy away from uncomfortable truths.
03:37Can the houses here near the riverbed stay?
03:40Or will they have to make way for additional protective measures?
03:44Rebuilding everything time and again would eventually become too expensive.
03:51We'll never achieve 100% security.
03:55On the one hand, it's barely feasible, both technically and financially.
03:59On the other, in light of climate change, uncertainty about how things will develop in the future is quite high.
04:08Tens of thousands of cubic metres of debris had to be removed, not just from the protective wall here.
04:14Brienz aims to start afresh, despite knowing that catastrophes like this
04:19are coming more frequently for Swiss mountain towns.
04:22A rethink is inevitable.
04:26What would it mean if safety could no longer be assured?
04:30Does it mean certain areas would become unusable?
04:34That some settlements, especially in highly exposed mountain regions, might even have to be abandoned?
04:45Abandon entire villages because climate change makes it too dangerous to keep living there?
04:51In nearby Guthanen, that decision has already been made.
04:55The houses here have been evacuated.
04:58Franziska von Bergen and her family will soon move further down in the valley
05:03into a new, safer home.
05:07You're grateful you can leave before something happens.
05:10It just shows how quickly something like that can take place.
05:13Depending on the situation, you might not have time to react.
05:20In Swiss alpine towns, residents know, no matter how idyllic it may look,
05:25there's no denying the forces of nature.
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