杏吧原创

Saharan dust could increase the risk of avalanches in the French Alps

Dust from the northern Sahara can darken snow in the French Alps, which makes the snow absorb more heat and melt. This can lead to a higher risk of skiers triggering slab avalanches
The French Alps can take on an orange hue when Saharan dust is carried north
Getty Images/Image Source

Saharan dust has been blamed for everything from rain leaving marks on windows in the UK to potentially having a role in melting sea ice in the Arctic. Now it seems the dust could even play a part in making avalanches more likely in Europe.

The dust has regularly turned skies above French mountains a dramatic orange, with adding sand to ski slopes and making the landscape look more like Mars than the Alps.

Marie Dumont at the French weather agency M茅t茅o-France and her colleagues ran computer simulations of how snow behaved with and without dust deposition in the French Alps. They found that the dust has a greater effect in certain weather conditions, and can make snowpack more unstable and avalanches more likely.

鈥淭he primary impact is the change of colour,鈥 says Dumont. The team found that the change in the amount of light being reflected as the snow grows darker leads to more energy coming into the snowpack, an increase in temperature and then accelerated melting as a result.

The findings aren鈥檛 yet peer-reviewed and were presented at a meeting of the European Geosciences Union on 27 April. The team said the computer modelling showed dust deposition leads to a period with a 鈥渉igher risk鈥 of skiers and snowboarder triggering slab avalanches. The balance of risk depends on how much dust is deposited, which direction the slopes face and the altitude.

One of Dumont鈥檚 colleagues, Oscar Dick at the WSL Institute for Snow and Avalanche Research in Switzerland, says for now the work relies entirely on snow models and computer simulations. No fieldwork has yet made been to corroborate the results, he says.

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