Unprecedented Lake Appears in Frozen, High Altitude Landscape: 'Snow Is Permanent in the Alps...It's Not Supposed to Melt'

A recent heatwave in Europe created a lake high up in the French Alps at altitudes of more than 11,000 feet, in a place where temperatures are normally too cold to support liquid water.

The lake, measuring around 100 feet-wide, was spotted by rock climbing instructor Bryan Mestre at the base of the Dent du Géant and Aiguilles Marbrées mountains in the Mont Blanc massif range, which extends into France, Italy and parts of Switzerland.

Towards the end of June, Europe experienced a sweltering heatwave that saw the mercury rise to record highs in some areas. On June 28, for example, France recorded its hottest ever temperature—114.6 F in the town of Gallargues-le-Montueux near the country's Mediterranean coast—according to the state forecaster Météo-France.

Despite the much higher altitudes, the Alps mountain range was not spared from the heat, leading to widespread melting of snow and ice. The popular resort of Chamonix, for example—which lies at 3,400 feet—experienced temperatures of up to 97 F.

"I was surprised to see [the lake]—in the Alps above the 3,000 meter line [around 9,850 feet,] water is always supposed to be in a frozen state," Mestre told the London Evening Standard. "When we go climbing for a day, if we bring a bottle of water or a camelback, the water starts to freeze after a few hours, even though it was in our backpacks all along, to give you an idea."

"I have seen similar events in the Andes or in the Rockies, but the ecosystem is a lot different there," he said. "Snow is permanent in the Alps above 3,000 meters—it's not supposed to melt. Of course, with the whole global warming deal, it does melt, but it doesn't get this big. I'm not a scientist but it's obvious that it's a direct effect of the heatwave that [struck] Europe in June."

Mestre posted two pictures, taken only ten days apart, on Instagram of the area to demonstrate how quickly it had formed.

"[One] was taken earlier on June 28, the second one was shared by Paul Todhunter," Mestre wrote in the post. "Only 10 days of extreme heat were enough to collapse, melt and form a lake at the base of the Dent du Géant and the Aiguilles Marbrées."

"That I know, this is the first time anything like that has ever happened. Southern Europe and the Alps have been struck by a massive heatwave; the below-freezing altitude was as high as 15,400 feet and during the day, temperatures as high as 50 Fahrenheit were felt on top of Mont Blanc," he wrote. "This is truly alarming, glaciers all over the world are melting at an exponential speed."

Dent du Géant, Alps, France
The lake was spotted at the base of Dent du Géant in the Mont Blanc massif. JEAN-PIERRE CLATOT/AFP/Getty Images