Climate change is turning the snowy white Alps green
As snow cover is decreasing in the Alps, green space is growing.
The European Alps are one of the world’s most iconic mountain ranges. The snow-capped peaks are renowned for their winter sports and unique alpine ecosystems, especially in places like Mont Blanc—the highest peak in the Alps, known as the White Mountain. But these places are increasingly impacted by climate change, putting their snow cover and names like the White Mountain, at risk.
New research shows how the creeping loss of snow cover and increase of vegetative land cover, as consequences of climate change, have impacted the European Alps over the past 40 years. The study, from the Spatial Ecology Group at the University of Lausanne in Switzerland and recently published in the journal Science, reports that there’s been enough snow cover loss that the change is visible from space.
But the more significant part of the research focuses on the increase of vegetative cover, or “greening” of this mountain region. Nearly 80 percent of the Alps above the tree line have experienced this rise in plant growth, which has severe implications for the ecosystem and could potentially accelerate certain factors that contribute to climate change.
Snow cover is dropping
The study team, led by Sabine Rumpf of the department of Ecology and Evolution at the University of Lausanne, used remote sensing and satellite images to observe land cover changes across the whole European Alps. They found that summer snow cover, which is typically present from June through September, had a stronger decline than snow cover that lasts all year. This significant decrease in snow coverage was present in 10 percent of the area they studied.
The researchers used two methods to measure the change in snow cover. For summer snow cover, they measured how long and how much snow lasted in certain areas over certain months. For year-round snow cover, they identified only whether snow was present—not how much was there. Different factors shape the loss of these different kinds of snow cover, which can point to various climate issues.
“The loss in year-round snow might suggest that a different threshold is being crossed, because it’s going from one land cover type to another,” Adrienne Marshall, a hydrologist at the Colorado School of Mines who specializes in snow, says. Areas that saw a decrease in year-round snow were more likely to have shorter summer snow cover, too. But greening only coincided with changes in snow cover in a fraction of the Alps, the study showed.
Snow matters. Though 10 percent may seem like a low number, the researchers emphasized in their paper that this change is indicative of an important global warming trend. Mountain glaciers and snowmelt provide half of the world’s freshwater. The length of growing seasons for alpine plants are shaped by how long snow cover lasts. Snow cover also serves as a distinct water source for plants that rely on snow melt—less snowmelt throughout the growing season will be increasingly problematic as droughts become more frequent and severe.
Experts predict that the European Alps will lose up to 25 percent of its snow mass over the next 10 to 30 years. At the same time, the “greening” in the Alps has increased significantly. A previous study in 2021 concluded that only 56 percent of the mountain range had seen more plant growth. Rumpf and her team calculated a number that’s closer to 77 percent, which includes a boom in native alpine plants as well as newly colonizing species. The increased plant growth, the paper explains, is largely catalyzed by changing precipitation patterns and growing seasons due to climate change.
“The scale of the change has turned out to be absolutely massive in the Alps,” Rumpf said in a press release.
While there are potential benefits of more plants that can suck carbon dioxide out of the air, researchers say that the negatives outweigh the good.
“From the perspective of global change feedbacks around carbon sequestration, plant productivity feedback in this region might not be that important,” Marshall says of the study. Mountain regions don’t see as much plant growth as other places around the world, like in the tropics, so any additional plant growth that does occur likely won’t have as much of an impact on carbon sequestration as other regions with a richer plant ecosystem.
But other feedback systems could have meaningful impacts: An uptick in plants in the Alps will alter snow patterns, speed up snowmelt, and reduce snow cover. Reduced snow cover combined with greener mountains also means less albedo effect, which occurs when the white frosty layer reflects sunlight back into the atmosphere. This feedback loop speeds up the warming process around the world, causing furthers glacier melt, permafrost thaw, habitat loss, and fading snowcaps
On the bright side, Marshall says studies like these help researchers like her gain a better understanding of how climate change affects snow and related ecosystems.
“It gives us a useful regional look at some concurrent changes between snow and greening that help us get at those potential impacts on vegetation and potential feedback loops,” Marshall says.
“You get different changes at different locations,” Marshall adds, explaining that being able to compare changes in different ecosystems and parts of the world clarifies how she understands her own areas of expertise. “It helps to see that.”