Alps see record glacier melt during Europe heat waves

WEATHER NEWS: Alps see record glacier melt during Europe heat waves


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Pascal Egli has run on trails winding through the Alps for nearly two decades, but until this summer, he had never seen the mountains so bare.

Extreme heat waves had transformed the mountain landscape. Routes once considered easy were now dangerous. Snow bridges over crevasses collapsed, making certain areas impassable. Rocks had tumbled unexpectedly from glaciers and bare mountainsides, injuring and even killing some in their path.

“By mid-June, it was really, really kind of shocking,” said Egli, who received his PhD in glaciology from the University of Lausanne in Switzerland this summer. “It was getting so hot and things are melting so fast, you couldn’t safely do certain 4,000-meter [13,000-feet] peak routes anymore because some crevasse bridges were a bit unsure.”

By the end of June, many mountaineers stopped going out on the glaciers — months earlier than normal. While European glaciers have been shrinking for decades, data and field reports show that the melting this summer is the most severe on record. Some glaciers have melted one to two months faster than normal, which researchers say is the latest drastic example of the effect of human-caused climate change.

And there’s already been wide impact: Ski resorts across the Alps closed the summer ski season early because of unsafe conditions. In rare occurrences, normal, easier routes were closed on mountains including Mont Blanc and Matterhorn.

“I would say it is off the charts compared to anything we’ve ever measured before,” Mylène Jacquemart, a glaciologist at ETH Zurich, said in an email. “We are currently seeing conditions that, even in a pretty bad year, we would only expect at the very end of the season. When we calculate the final mass balance at the end of September, I expect that it will be the worst year on record by a large margin.”

Andrea Fischer, a glacier scientist at the Austrian Academy of Science, agreed that this year’s melt season is exceptional. “This melt season does not compare to others, as we have no evidence of such an extreme melt in our records,” which began in 1948. Data shared with Reuters indicated mass loss in the Alps is the highest in at least 60 years.

The Alps, as well as other European glaciers, play an important role in the region. Mountain snowpack provides water to major rivers, delivering up to 90 percent of water to lowland Europe for drinking, irrigation and hydropower. The Alps also attract more than 120 million people, like Egli, for adventure sports and to ski resorts. Declines in these Alpine glaciers can stress the economy, and the loss in snow cover can exacerbate global warming and increase sea level rise.

Winter rubble brings summer trouble

Punishing summer heat waves triggered the melt, but processes that initiated the rapid melt off began months ago.

Winter snowpack was lower than normal — only half the typical amount at the end of the season, Jacquemart said — limiting the growth of the glacier. For instance, Switzerland’s Gries Glacier recorded its lowest snow quantity on record at about 53 percent below average in April.

At the end of winter and early spring, large plumes of dust from the Sahara coated the snow surface, darkening the glaciers. The darker surface absorbed more sunlight rather than reflecting it back into space, helping to warm what little snow had fallen.

Spring was also abnormally warm and dry for much of Western Europe, with little snow falling at high elevations on the glacier.

Then summer heat came in full force early on. Southwest Europe reached its highest average May maximum temperature in 55 years of records. Then Europe experienced its second-warmest June on record.

“The combined heat and lack of precipitation have put the glaciers in a state that is unprecedented,” said Jacquemart, who also works at the Swiss Federal Institute for Forest, Snow and Landscape Research. It’s alarming because there isn’t just one glacier experiencing high melt, but “rather the fact that the situation is so bad everywhere in the European Alps,” she said.

Satellite data showed several glaciers shrinking after a heat wave in mid-June that brought temperatures 10 degrees Celsius (18 Fahrenheit) higher than average in some regions. After about a week of unusually high temperatures, the Sabbione Glacier, which feeds into a hydropower reservoir, lost about 35 percent of its snow cover, according to glaciologist Mauri Pelto.

Losing snow cover early in the melt season is problematic because bare glacier ice melts 50 percent faster than if it were covered with snow. As heat waves continued, melting hastened in July.

“Glacier melt there in July was higher than the ever-recorded maximum for the full season,” Fischer said..

Satellite data shows significant melting of the Rhone Glacier, which feeds into the Rhone River, from June to July. By July 15, the snow line on the glacier was located at 2,950 meters (9,700 feet) — about 150 meters (500 feet) higher than is typical for this time of the year.

Egli remembers running along a snow-covered ridge in the central Switzerland Alps with his dad when he was 12 years old. It was one of his first mountaineering adventures before he competed professionally. At the summit, he could see Zurich in the distance. Snow covered the summit slope facing the city even in the summer.

Two decades later, he visited to find the area was mainly rock and debris, the snow cover gone both on the ridge and the summit face. A glacier leading from the summit was now bare ice because temperatures have become too warm to retain the snowpack. Ice and firn, or dense snow leftover from previous seasons, also disappeared from the ridge.

Mountaineering practices have already changed in the past few decades in response, he said. Some routes are now only safe in April or May — before the trail becomes too dangerous.

Egli said he began to realize that “some of the glaciers we used to run over, they simply won’t exist anymore.”

Fischer said the shifts coincide with long-term changes in the climate. Since the 1980s, the Alps have experienced an increase in temperature from 0.2 to 0.5 degrees Celsius per decade (0.36 to 0.9 Fahrenheit) — significantly affecting snowfall and melt during the spring and summer.

“In the last 2 decades, the lack of summer snow got normal, and the melting season was getting longer and longer,” Fischer said in an email.

According to the Research Center for Alpine Ecosystems, the duration of snow cover near the valley floor of the Northern Alps has been reduced by five weeks since the 1970s. By 2050, snow cover could be reduced by another four to five weeks.

Additionally, the number of hot days could increase by 15 to 30 days on the valley floor and in the mid-mountains. Today, the areas only experience two to five days of such temperatures.

“Northern Europe is a part of the globe which is projected to become warmer yet than the rest of the world,” said W. Tad Pfeffer, a professor at the University of Colorado at Boulder. “The Alps have been hit very hard. Glaciers are shrinking in Alaska, but not like the Alps.”

In rare cases, the rapid melt can spur exceptional events like the collapse of Marmolada Glacier in Italy’s Dolomites region. During a heat wave in July, a glacier chunk separated from the mountain and triggered an avalanche of ice, rock and debris below, killing 11 hikers.

“All glaciers in the Alps are suffering from heat and the melting processes are accelerated. In the Dolomites, the glaciers are generally smaller and thus more sensitive to climate change,” said Mauro Valt, a glaciologist at the Arabba Avalanche Center.

Outside of the Alps, other mountainous glaciers have also experienced record melt. Glacier melt in Svalbard, Norway, saw its most melt on record during the first two months of the summer.

“We would not be seeing this in the absence of [human] influence on climate,” Pfeffer said. “Things that became kind of once-in-a-lifetime events started to become kind of routine. … We’re seeing the future.”





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