Early summer heat is wreaking havoc on Alpine glaciers

Today is the summer solstice: the longest day of the year, or the shortest night. In any case the longest period of daylight. Typically, this marks the beginning of the (astronomical) summer. Typically, June is not the warmest month of the year though. July and August are usually considerably warmer in European countries.

However, this year is different. After the warmest May in large parts of Switzerland (since 1868), June has brought a giant heat wave upon the Alps. Temperatures rose to 38 degrees C in the Basel-area but still above 30C in Wallis at 1000 m and close to 26 in Rosswald at 1800m! And what do you think about +6C on the “Klein Matterhorn” at 3873m?

All of this heat is creating a very early snow melt in the mountains, where the snow cover (or lack thereof) is now about 2 months ahead of schedule: the glaciers are now just as exposed as usually mid-August. This has 3 reasons:

  1. Dry winter with little snowfall.
  2. Sahara dust, which makes the surface darker (and thus easier to melt)
  3. The earlier described heat.

Just below, you can see a picture taken by Matthias Huss (a glaciologist) and his team, whilst on a fieldwork trip.

It’s not just Switzerland

However, it’s not just Switzerland. Also the Zugspitze, Germany’s tallest mountain, has been free of wintersnow since last week. And the situation isn’t any different at the Pasterze Glacier on the flanks of Austria’s tallest mountain the Grossglockner. Similarly, Italy is having perhaps an even more worrying status as the drought in the Italian Alps has been even more severe with water levels in the main river Po being at dangerously low levels. The Po river depends on the melting of snow from the mountains – which simply hasn’t been there to start with.

This winter snow is essential. Not just to provide water as it melts, but also as protective cover over the ice. White snow reflects considerably more solar energy than the darker ice. When this snow is gone, the protective layer is too: exacerbating the melting.

This in turn leads to rapid retreat of the glaciers and causes local warming to be stronger and more ice to melt. Anybody who has ever stood near a (major) glacier knows how strong the local winds can be and how much it reminds you of a refrigerator. Even on a hot summer day, the glacier provides a lot of local cooling as most of the energy is consumed by melting the ice.

And although melting can go really fast: it takes decades to form a new layer of ice. Melting of glaciers is not a lineair process as a result of normal variability, even though in climate scenario’s it’s usually mapped out as a lineair event. In reality, it goes with bumps and troughs. Years of (very) rapid retreat, and years with slower retreat. This year is definitely going to be a year of very rapid retreat.

Ramifications for hikers

This might all sound quite “abstract” and far from your bed. However, it poses real short-term threats. In recent history, problems with glacier collapses have been reported and caused complete villages to be evacuated. Routes have been changed (like near Gadmen), bridges to be made and some glacier passings are no longer safe to do. On the other hand, some routes that were not possible in the past have now opened up and new lakes are present on locations where your maps don’t show it yet.

Another risk is decreased run-off time from the mountains. With lower temperatures and larger glaciers, more precipitation falls as snow. This takes longer to come from the mountain, as it first needs to melt. With increased freezing levels, more water runs off more quickly. This happened in the Combe du Monde near Sixt-Fer-a-Cheval on July 20, 2007.

Besides all of the above: mountains with glaciers add to the view and the experience of being in high-alpine terrain. Losing them will be such a waste – but it’s happening fast.

Glacier des Laschaux (Grandes Jorasse, Mont Blanc area), screenshots from webcam at windy.com. The bare ice is exposed.

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