REPORTAGE
Christophe Boloyan knows the Alps by heart. Rocks, refuges, snow, and even ski resorts. And it is on these latter, too, that this historic guide of Chamonix saw the effects of global warming. Not only because the snow cannons are more and more solicited, due to lack of natural falls. But also because we have to intervene more and more often on infrastructures. Chairlifts, ski lifts, gondolas ... all these lifts mounted on pylons are threatened by rising temperatures.
"The pylons of the ski lifts are sinking"
"These are the bases of pylons that tend to sag," says Christophe Boloyan about the gondola Bochard, at 2,700 meters above sea level, in the massif des Grands Montets. With warming, soils do not freeze permanently. The rock creaks, or moves, which destabilizes the lifts. "The inclination of the towers and the cable is completely changed, but it is precision mechanics, the cables must be in perfect alignment, we can not admit a modification of this magnitude."
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Last winter, the Bochard gondola moved so much that a million euros of work was committed to consolidate it and plant metal rods at 12 meters deep. The result: an unexpected month of closure during the ski season. And this is not the only example. Between 5 and 10% of ski lifts would be affected, according to scientists who constantly monitor the Alpine basement.
An entire hut sheltered
"We have cases, such as the Rosaël chairlift in Orelle Val Thorens, where the arrival station had to be moved and rebuilt 30 meters upstream due to the melting of permafrost," says one of these specialists, Pierre-Allain Duvillard. Which nevertheless ensures that this poses no risk for skiers. "The infrastructures are very well followed and as soon as we have a pylon movement, the operator sees it directly and closes." The deployed solutions can be a consolidation, as in Bochard, or a construction on stilts or with adjustable foundations, as in the regions where there are earthquakes.
And mountain huts are not spared. "A fairly emblematic refuge, the bivouac Periades, filmed in Premier de Cordée , failed to collapse this summer," recalls our guide, Christophe Boloyan. At 2,600 meters, "all the ground has collapsed" and "tilted quite impressively."
This jewel of mountain architecture has been saved. A group of guides conducted an expedition to hoist with straps and carry it a little lower until the ground stabilized. But Christophe Boloyan is worried about the extent of the warming. "When we talk about landslides, they are blocks the size of a car or a semi-trailer, we can observe from one year to the next what happens, but even from one day to the next. the other sometimes. "
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