The Effect of Climate Change on the Alps

At 6am, there were over a hundred people waiting for the cable car to transport them from Chamonix to the top of Aiguille du Midi, a peak in the French Alps that stands at 3,842m (12,604ft). This popular attraction offers a 20-minute ride in a cabin that provides stunning views of Mont Blanc. The summit boasts a rocket-shaped structure that includes man-made tunnels and platforms, making it a unique laboratory for researchers.

According to Matan Ben-Asher, a geomorphologist at the Laboratory of Environment Dynamics and Territories of the Mountain (Edytem) at University Savoie Mont Blanc, the site offers easy access to an extreme environment. Ben-Asher and his colleague Josué Bock spent several hours hanging from static ropes about 200m (656ft) above the glacier, maintaining part of a sensor network installed through deep boreholes into the rock walls of Aiguille du Midi. They were repairing a broken cable that connects the electrodes of a device for measuring electrical resistivity. This expensive instrument is typically used to detect water and minerals in soil but is not designed to withstand freezing temperatures and frequent lightning strikes experienced on the rockface beneath the cable car station.

Despite the challenges, the scientists are using the device to monitor permafrost in the rock walls, a soil and rocky material that remains frozen continuously for at least two years. While permafrost is typically associated with the polar regions, it can also be found on steep mountain walls. In the European Alps, more and more permafrost is thawing each year, posing a threat to the mountains where it is located.

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It was only 6am, yet there were already over a hundred people queuing for the cable car that leads from Chamonix to the peak of Aiguille du Midi in the French Alps. This scene repeats almost every day during the busy summer months. The 20-minute ride in the cabin that carries passengers to the top of the 3,842m (12,604ft) peak is one of the most popular attractions in the French mountaineering capital.

The peak boasts a rocket-shaped structure complete with man-made tunnels and platforms, making it a unique laboratory for researchers. “This place is unique because it gives us easy access to a very extreme environment,” said Matan Ben-Asher, a geomorphologist at the Laboratory of Environment Dynamics and Territories of the Mountain (Edytem) at University Savoie Mont Blanc, in Chambery, France, while exploring the tunnels with his colleague Josué Bock.

The two researchers rappelled from the platform above the east face of Midi to repair a broken cable that connects the electrodes of a device for measuring electrical resistivity. Despite the challenges, they are using the expensive instrument to monitor permafrost in the rock walls. Permafrost, a soil and rocky material that remains frozen continuously for at least two years, is commonly associated with polar regions but can also be found on steep mountain walls. In the European Alps, more and more permafrost is thawing each year, which poses a threat to the mountains where it is located.

At only 6am, over a hundred people are already waiting for the cable car that leads from Chamonix to the peak of Aiguille du Midi in the French Alps. This is a familiar sight during the busy summer months. Riding the cabin to the top of the 3,842m (12,604ft) peak in only 20 minutes is one of the most popular attractions in the French mountaineering capital.

The rocket-shaped structure carved into the peak’s top, with man-made tunnels and platforms, offers visitors breathtaking views of Mont Blanc and serves as one of the most unique natural laboratories in the world. Matan Ben-Asher, a geomorphologist at the Laboratory of Environment Dynamics and Territories of the Mountain (Edytem) at University Savoie Mont Blanc in Chambery, France, says, “This place is unique because it gives us easy access to a very extreme environment,” while he and his colleague Josué Bock rappel from the platform above the east face of Midi, maintaining part of a sensor network installed through deep boreholes into the rock walls of Aiguille du Midi.

One of their tasks is to repair a broken cable that connects the electrodes of a device used for measuring electrical resistivity. This expensive instrument is commonly used for detecting water and minerals in soil but is not built to endure the freezing temperatures and frequent lightning strikes it experiences on the rockface beneath the cable car station. However, keeping it running is a vital task as, up here amidst the clouds, the scientists are using it to monitor permafrost in the rock walls.

Permafrost in the Alps is typically found above 2,500m (8,202ft), where it runs deep into cracks in the solid rock, helping to stabilize them. The mountainsides become unstable without it. The thawing of permafrost is occurring on two different timescales. Short-term thaws happen every summer, but heatwaves, which have become more frequent in the French Alps since 2015, are taking their toll.

Florence Magnin, another member of Edytem lab and one of the most prominent researchers studying how Alpine permafrost is affected by climate change, explains that “If summer is warmer, the active layer, which means the layer above the permafrost that is always thawing in the summer, is becoming deeper every year. This means that part of the layer now thaws for the first time ever, which can provoke destabilization in the rock.” Long-term data collected from the sensor network embedded in the rockface shows that every ten years, the average temperature deep inside the rock has increased by 1C (1.8F), due to the gradual deepening of the summer thaw. Magnin notes that “This steady and slow warming can also provoke rockfalls.”

The degradation of ancient permafrost that fills the cracks deep inside the walls is the main cause of unusually large rockfalls. Ludovic Ravanel, from Edytem Laboratory, notes that “This kind of permafrost is usually not reachable, but rockfalls gave us the opportunity to date the ice. It was between 800 and 4,500 years old.” Yet despite its age, it appears to be melting away.