Global warming has shortened the snow season in the Swiss Alps by 37 days, as maximum snow depths have dropped by 25 percent since 1970.
By Bob Berwyn
Winters are getting much shorter as the planet heats up. (Photo: Bob Berwyn)
Old-timers in the European Alps sometimes say skiing was better 30 or 40 years ago, and detailed new research by Swiss scientists suggests those claims are based on more than just nostalgia.
Heat-trapping pollution from burning fossil fuels has shortened the season, and a new study in the December 2016 issue of Climatic Change has measured that decline using hard numbers, documenting a dramatic drop in the number of snow-covered days in the Swiss Alps during the modern global warming era.
On average, the snow season in famed ski regions like Davos, Zermatt, and Grindelwald starts 12 days later and ends 25 days earlier than it did in 1970, the scientists found after analyzing readings from a set of 11 weather stations spread across Switzerland at elevations ranging from 1,100 to 2,500 meters (3,600 to 8,200 feet). The study also concluded that the maximum annual snow depth at the 11 sites has declined by 25 percent since 1970, and that the date of the annual maximum snow depth is now nearly a full month — 28 days — earlier than in it was 45 years ago.
The study was led by scientists with the Swiss Institute for the Study of Snow and Avalanche Research and the Federal Institute for Forest, Snow and Landscape Research.
This year, parts of the Swiss Alps, as well as nearby parts of France and Italy, saw the driest December in 100 years. The Alps have warmed about 3.6 degrees Fahrenheit in that same period, almost twice as fast as the global average. Italian mountain researchers recently documented another surge in warming starting about 30 years ago. Other Swiss climate scientists project that, by the year 2100, the snow line will be 500 to 700 meters higher, and the snow season will be shortened by another four to eight weeks.
The new Swiss study shows that even the highest reaches of the Swiss Alps are vulnerable to global warming; previous studies had suggested that year-to-year changes in weather would mask warming impacts at higher elevations, but that was not the case. Researcher Martine Rebetez, with the University of Neuchâtel, says the team was surprised at the strength of the climate signal even at mountaintop levels.
“For now, the higher elevations may still have good snow when lower elevations lack [it], but that’s not going to last for too long. Some resorts that are at higher elevations thought they would be safe for some time, but it’s changing pretty fast, and it’s connected to increasing temperatures,” Rebetez says. “It shows that things are also changing at higher elevations, and it corresponds to the last quite strong period of temperature increases,” she continued, explaining that previous studies had focused more on lower elevations where the changes were already obvious.
Dwindling snowpack in the Alps and other mountain regions has been well documented by previous studies, including United States Geological Survey research showing a 20 percent decline in the Rocky Mountains’ spring snowpack, and a 35 percent drop in the Cascades.
These findings are important for the Swiss ski tourism industry, which has invested heavily in snowmaking to cater to more than 23 million skiers each season. “During the last years, some months, some weeks, it has not even been possible to make snow because it was too warm during the early season,” Rebetez says. There are also long-term implications for water supplies across much of Europe. Major central European rivers, including the Rhine and the Rhône, are fed by the snows and glaciers of the Swiss Alps, she added.
The overall decline in snow cover is most noticeable in the spring, with an earlier onset of warmer temperatures leading to a faster meltdown, the scientists concluded. These findings are in line with data compiled by the Rutgers Global Snow Lab, which shows a steady and massive drop in northern hemisphere spring snow cover, from about 32 million square kilometers in 1967 down to about 28.5 million square kilometers in 2015.
The changes measured by the Swiss team have caught the eye of climate experts at the European Environment Agency, which has catalogued the impacts of global warming on ice, snow, and permafrost in several studies.
“We’re already seeing impacts to winter tourism, with declines in regions closer to the snow line, where lifts are no longer operating,” says Hans-Martin Füssel, an adaptation expert with the EEA. The dramatic temperature increases in the Alps call into question some of the massive infrastructure investments for snowmaking, which are also controversial in terms of water, energy and sustainability, Füssel says.
Along with impacts to skiing, the loss of snow cover in the Alps and elsewhere is also a threat in other ways, Füssel adds.
“Snow cover also plays an important role for ecosystems, as snow protects the ground from extreme cold,” he says. “Plants have an easier time under snow cover, and if snow is melting refreezing and creating an ice layer, it makes it harder for plants and animals. It’s already a significant problem for reindeer in Lapland.”