How to climb Cosmiques Arete

DANGER: There has been significant rock fall on Cosmiques Arete. Seek advice before tackling the route.

When I first started alpine climbing Cosmiques Arete was at the top of my tick-list. And later, when I started taking friends in the mountains, I told them this was the line to climb! Now, as a guide, I never tire of following this perfect arete, with one foot on the steep north face dropping steeply away to Chamonix 2,000m below, and the other on the sunny side high above the Midi plateau, looking out to the Aiguille Verte, the Grandes Jorasses, the Dent du Geant, the border to Italy beyond, Mont Blanc du Tacul and all the way to Mont Blanc.

The quick access to the ridge and the relatively easy level is what makes this ridge so popular – sometimes, overly popular. It’s good to avoid Cosmiques in the summertime and on weekends, as lots of people who don’t know how to move efficiently along a ridge can create bottlenecks on the crux sections of the climb.

Accessing the ridge

But back to the quick access: riding the Aiguille du Midi lift to 3,842m is an already thrilling experience. Built in 1955, this was then the world's highest cable car. The view from the windows over the North Face of the Aiguille du Midi is spectacular.

From here, descend the sometimes knife-edge ridge from the top of the Aiguille du Midi to access to the Midi Plateau. In itself, it's a good way to sharpen your skills at down-climbing in crampons with the exposure of the north face lapping at your feet.

The hike across the Midi Plateau is much more mellow, and will give you time to take in the view and watch a few climbers enjoying the perfect orange granite of the South Face of the Aiguille du Midi. Pass the Cosmiques Hut and then start climbing back up to the start of the ridge proper; a break by the old Abri Simond shelter is usually in order first.

Starting the climb

Depending on conditions, remove your crampons or keep them on. The ridge hereafter is either an easy snow climb with a few easy rock moves earlier in the season; or if the snow has melted away, a more demanding climb. When in doubt as to where the route goes, follow the rock that is most scratched by crampons. It's hard to get lost!

The first section stays mostly close to the ridgeline. When you reach the first sub-summit, you have to do two abseils, or a down-climb and abseil. The anchors are fixed but the rappels are 25m long so make sure you pack at least a 50m single rope.

Crux one

From the bottom of the last rappel, contour and then climb the backside of a big and obvious gendarme. This is one of the cruxes of the route as the climbing is a little bit technical. To move people along, local guides drilled perfectly placed holes to fit your crampons into: one foot on the right, backstop the left foot, lean over and grab the backside of a flake and mantel on the small platform. Up and left are a pin and bolt to belay your partner.

Next, you down-climb a few metres using perfect vertical cracks to balance your way down, before climbing up a steeper mixed or snow pitch, depending on the season, to get back on the ridge proper.

But not for long. Look for an obvious slanting corner to the right and keep traversing while contouring another small gendarme. There the route traverses the south face for quite a way, but there many horns along the way to protect your party. Another little descent followed by a snow climb will have you contouring the last majestic gendarme on the ridge.

From here you might get to watch a strong crack climber try to free climb Digital Crack, the highest 8a in the world, which was first climbed by Thierry Renault and Alain Ghersen. But stay focused here as the crux is coming up next. If you’re there on a busy day, you can sit here for a long time, watching people do their best to climb this 5m section.

Crux two

From the bottom of the last rappel, contour and then climb the backside of a big and obvious gendarme. This is one of the cruxes of the route as the climbing is a little bit technical. To move people along, local guides drilled perfectly placed holes to fit your crampons into: one foot on the right, backstop the left foot, lean over and grab the backside of a flake and mantel on the small platform. Up and left are a pin and bolt to belay your partner.

Next, you down-climb a few metres using perfect vertical cracks to balance your way down, before climbing up a steeper mixed or snow pitch, depending on the season, to get back on the ridge proper.

But not for long. Look for an obvious slanting corner to the right and keep traversing while contouring another small gendarme. There the route traverses the south face for quite a way, but there many horns along the way to protect your party. Another little descent followed by a snow climb will have you contouring the last majestic gendarme on the ridge.

From here you might get to watch a strong crack climber try to free climb Digital Crack, the highest 8a in the world, which was first climbed by Thierry Renault and Alain Ghersen. But stay focused here as the crux is coming up next. If you’re there on a busy day, you can sit here for a long time, watching people do their best to climb this 5m section.