Mountain Stability in the Mont Blanc Massif -  Summer 2022

What follows is a summary of a discussion/Q&A that was organised by IFMGA guide Martin Elias on behalf of Chamonix Experience in early August 2022.

It was presented by Ludovic Ravanel, geomorphologist, IFMGA guide and instructor at the Ecole Nationale de Ski et Alpinisme, the French national centre for mountaineering in Chamonix.

The interpretation of his words and their translation from French are by British Mountain Guide Andy Perkins. He accepts no responsibility for injury or death that may occur when following this advice. You are reminded that mountain conditions are, by their nature, changeable and that climbing is an activity with inherent risks to the participant.

 

 

The Situation

The mountains around Mont Blanc changed very little in the previous six to seven thousand years but are now changing very rapidly. The alpine areas are warming two or three times faster than the rest of the world on average.

Inspection of images of the Mont Blanc Massif show very little change to snow cover from the end of the last mini ice age (c.1850) until around 1980. In the last 20 – 30 years, the rate of change has been significant. The effect of climate change on the mountains was noted in 2003, when the Goûter hut was closed due to rockfall in the Grand Couloir. In 2005, a large part of the Bonatti Pillar on the Drus collapsed.

It was around this time that investigation into the link between permafrost and rock collapses was started. A relationship was suspected in research from the ‘70s through to the ‘90s, but now there is a firm statistical link between the two.

Specifically, we are concerned by areas above 2,300-2,500m on north aspects, and above 3,300- 3,500m on south aspects. This is where we know there is permafrost thanks to an increasing number of temperature gauges (now over 100 in the Mont Blanc Massif). With this “heat map”, it is possible to correlate permafrost and increased rockfall activity.

You might think that rockfall/collapse would only increase once the temperature of the rock goes above 0°C, but in fact it becomes a concern from about -3°C.

Alongside melting of permafrost, the loss of thickness of glacial ice is an important contributor to geological instability. The rock underneath the ice expands due to there being less weight of ice on it (known as post glacial decompression). This is what is happening at the base of the south face of the Midi, for example.

In 2015, the Goûter was also closed for the same reason as in 2003, and since then there have been heatwaves in four of the six summers that followed (as well as the ongoing one).

The big difference in 2022 is that:

1. It was a low snow winter.
2. May was very warm.
3. The first heatwave was in June. As a consequence, the warming of the rock started earlier and penetrated deeper into the rock. By mid-July, the internal temperatures of the rock on north aspects were the same as they would normally be at the end of August, so we are 4 – 6 weeks in advance of what happened previously.

On a slightly less grim note, temperatures on south faces are slightly lower than in previous years.

 

 

There have been 4 major rock collapse events so far in 2022:

• The Tour Ronde
• West face of the Dru
• Aiguille du Tacul
• Another incident in Italy

[Editor’s Note: Subsequent to this talk, there was a further significant rockfall, this time on the Cosmiques Arête].

In addition, there is very little snow on the glaciers. This means more ice is melting. There has been a 7m loss of thickness on the Mer de Glace and snow bridges are weaker than in the past.

 

Advice

Avoid North Faces Above 2,300m

For example, the north ends of the Marbrées and the Entrèves are suspect, so better to do these out and back from the south ends rather than as complete traverses.

The heat will keep going into these faces even if/when it starts to cool down, and there could be some big rockfalls this autumn.

 

Avoid Ridges

This is because the rock is being heated from both sides.

 

Avoid Couloirs

This is often where there are faults and more instability as a result, plus the debris gets channeled.

 

South Faces Up To 3,300m Generally OK, But Keep An Eye On Stuff Above

Glacial approaches to these faces may well be problematic.

 

Be Alert For Microsigns Of Impending Collapse

These include:

• Grating noises.
• Water running down cracks.
• Cracks getting wider than you remember (e.g. taking a larger size of cam).
• Gravel in cracks.
• Fresh rock on ledges.
• Rumbling noises like an empty stomach.
• Increased rockfall in general – for example there is rockfall below the Triangle du Tacul for the first time ever, meaning that there is no ice left in certain areas there.

 

Even in the lower areas, there can be a problem with the terrain drying out (aka desiccation), and then a bit of rainfall lubricates it. Hence the recent rockfall on Barberine.

After rockfall has occurred , the hang fire can stick around for a minimum of 10 years. In other words, don’t go to a place where there’s been a recent event in the assumption that it’s now more stable.

There is going to be a big event some time on the Red Pillar of the Blaitière. It might be tomorrow, it might be in 10 years, but there will be one.

 

 

The Good News

The Aravis is post-glacial, so less issue there (except for desiccation).

Aiguilles Rouges are generally good, though there is overcrowding on the Brevent. Even a short walk of an hour will get you away from many of the crowds.

The Valais is better too, as the strata are generally horizontal so less prone to slippage. One notable exception is the Matterhorn. Purging the Hörnli by removing rock will most likely accelerate penetration of heat into the mountain.

In July 2022, there were lots of “little” rockfalls. In August there are/will be less frequent falls but they will be bigger.

The permafrost will continue to be degraded by:

a) Conduction of heat.
b) Convection by either air in the cracks or (way worse) water. One of the lucky aspects of this summer is that it’s been dry.
    It will be important to keep an eye on the snow-rain limit when the next precipitation cycles come through.
    If it rains above 2,300m, the situation will get quite active.

It’s unlikely that the situation will get any better until there have been a few cold cycles. A heavy snowfall at the start of autumn would be bad, as it would insulate the ground below. The best scenario would be a long, cold, dry period, and then snow after that.

The best period for stability is the end of Spring when the rock is coolest.

The periods when routes come into condition will get shorter. One of the problems with social media is that everyone now knows when things are in, and so there are crowds/queues which lead to their own particular problems.

Alpinists need to be more reactive, and come to the mountains for an experience rather than a specific summit.

Ludovic referred to a need to “deseasonalise” the activity.

 

Structures in the Mountains

• The suspended pylon between Grands and Petits Flambeaux is becoming an issue.
• The foundations of the Grands Mulets too. (Access to the toilets is increasingly problematic).
• The Midi isn’t a problem just yet, but may well be in the future.
• It’s unlikely the Goûter hut will reopen this summer [Editor’s Note: The Goûter did subsequently re-open].

 

We are indebted to Andy Perkins and the organisers of this talk for allowing us to reproduce these notes. While the exact details may change in future seasons, there are many good principles here that alpinists should take note of as we approach climbing in an era of global warming.