Two key refuges on Mont Blanc have been closed by mayoral decree since August 11: Tête Rousse and Refuge du Goûter. The culprit is unrelenting rockfall in the infamous Grand Couloir, which guards the otherwise straightforward normal route up Mont Blanc.
The Grand Couloir, also known as the Couloir du Goûter, is no stranger to rockfall. Between 1990 and 2017, a mere sliver of Mont Blanc’s climbing history, 103 people died in the couloir, with another 230 injuries.
High summer is the most dangerous time for rockfall. Two climbers died a few weeks ago, despite taking all the standard precautions during their crossing.
The Goûter Route is one of two “normal” routes up Mont Blanc and is usually considered the easiest. The route begins at Nid d’Aigle, around 2,372 meters (7,782 feet), reached from Saint-Gervais-les-Bains by foot or the Tramway du Mont-Blanc. Next, the trail ascends terrain toward the Tête Rousse refuge at about 3,165 meters (10,384 feet).
Above Tête Rousse, the route heads toward the notorious Grand Couloir crossing, which is about 70 meters wide. The Aiguille du Goûter ridge follows immediately after (itself no stranger to rockfall, though there is far less exposure on this arête). The Gouter refuge sits at the top of this ridge at just over 3,800 meters (12,467 feet).
Above this point, much of the route is relatively straightforward glacier travel to Mont Blanc’s summit. Rather than rockfall, the chief dangers are crevasses, altitude sickness, hypothermia, sudden whiteouts, and severe weather.
Two issues make the Grand Couloir crossing a serious objective hazard. First, the Aiguille du Goûter is essentially a giant choss pile with loads of loose rock. Rocks tumble down every day, and have for thousands of years. Many of these are funneled into the large gully system that we call the Grand Couloir.
The second reason is melting permafrost in the European Alps generally, and the Mont Blanc Massif specifically. Ice inside the granite has glued many rock slabs together across the massif’s high altitudes. For centuries, if not millennia, this ice did not melt; therefore, it is called permafrost. In recent decades, climate change has caused this permafrost to melt more and more, especially in summer, leading to an inordinate number of rockfalls.
According to studies from 2012, 75% of rockfalls occur between 10 a.m. and 4 p.m. The risk increases in the summer and during sunny days. During peak hours around noon, a rockfall event occurs every 17 minutes. These figures are likely outdated, as melting permafrost has visibly increased the frequency of rockfalls, resulting in several summer closures since then. Unsurprisingly, most climbers pass at night to limit objective hazard.
The other normal route up Mont Blanc, known as the Trois Monts or 4,000’ers route, is also impassable, according to local guides. The bergschrund at the base of the Mont Blanc du Tacul is too wide to cross.
Though the two normal routes are out of commission at the moment, there are numerous other ways to ascend Mont Blanc. However, they require more technical ability.
Most importantly, when the mountains instruct us to stop with language this strong, we should all take a step back.