In his warm chalet decorated with photos of the summits and a collection of crystals, Jean-Franck Charlet is keen to tell the impact of climate change for guides. Arrived in this remote valley in 1530, the Charlets have been part of the local personalities for five centuries. “In 1821, Joakchim Charlet, my great-grandfather’s great-grandfather, was already a member of the Compagnie des guides de Chamonix. Since then we are all from father to son. I was an engineer and a guide. Today at 70 years old, I am attacking my 52nd season as a high mountain guide”, he says by way of preamble. Global warming worries him a lot. “Thirty years ago, we knew that to avoid falling rocks, we had to avoid certain corridors during hot hours. Today, rockfalls happen all the time. Danger is everywhere, even behind healthy, solid rocks. Last summer we had at least twenty significant collapses. Two years ago, a piece of the Cosmique ridge, which was a route for beginners, collapsed. Fortunately, it happened between two roped parties. The change is as rapid as it is impressive.”

And to continue: “The melting of glaciers like the Mer de Glace create enormous moraines, piles of earth and stones embedded together. These pebbles placed on steep slopes make the passages very dangerous. Rockfalls can happen at any time. When it rains, the falls are incessant. Under 2500 meters of altitude, his working conditions have completely changed. We had to change routes, find new ways. Until recently we climbed to the Argentières refuge by running on the slope of the glacier. Now, due to the melting, then the disappearance of the ice, it has become a maze of rocks. The change is amazing.” And higher? “The glaciers having melted from 30 to 50 meters thick, the climbing routes have lengthened by the same amount when it is possible to climb them, but sometimes they have only exposed impassable smooth rocks so we don’t go there anymore.” At Grands Montets, the famous off-piste skiing descent to reach the Pas de Chèvre is over. “You have to face a corridor of 30 meters on a slope of rocks. Even in winter, the passage is extremely dangerous because you pass near piles of rocks suspended in the earth. There were two deaths two years ago, that calmed everyone down.”

The other big change is the melting of permafrost at higher and higher altitudes. Thirty years ago, this ice which seals the rocks together never thawed above 3500 meters altitude. “Today, to find it intact in summer, you have to climb to 3800-3900 meters, he explains. When this permafrost melts, huge blocks collapse. This is what happened in 2005 on the great wall of Les Drus facing the Mer de Glace. The wall fell more than 600 meters in height. This jewel of climbing in Chamonix is ​​now inclimbable.»