Science

The Alps are getting greener – but that’s not a good thing

The Alps are getting greener - but that's not a good thing
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The European Alps are an iconic crescent-shaped mountain range associated with images of wintry peaks and snow-capped villages. But new research confirms a worrying winter sports destination trend: the Alps are turning from white to green.

In a study published Thursday in the journal Science, researchers report that a process called “greening” is occurring over large areas of the Alps. Although this term is sometimes used to refer to making a space more environmentally friendly, in this case it refers to an increase in plant growth and spread that can accelerate climate change.

Greening can potentially have some positive consequences, but the negative consequences outweigh these effects, said Sabine Rumpffirst author of the study and professor at the University of Basel in Switzerland.

This phenomenon occurs in 77% of the European Alps above the treeline – the edge of alpine habitats where trees stop growing. A earlier estimate reported that this occurred in only 56% of the region.

Rumpf and his colleagues also found that snow cover had decreased significantly in 10% of the Alps. These figures are based on an analysis of 38 years of data. Scientists evaluated the information captured by the Landsat missions, a group of eight Earth observation satellites that use remote sensors to collect data. Instead of looking at images, the team used this data to calculate snow cover spread and vegetation productivity.

Although 10% may seem small, the potential impact is significant. In addition to playing an important role in ecosystems, snow is essential for people as a source of drinking water. The Alps are the highest and most extensive mountain range in Europe. Forty percent of Europe’s drinking water comes from this region. This is why the Alps are called the “water towers” of Europe, Rumpf said.

Less snowfall doesn’t mean there will be less drinking water available tomorrow, but it does suggest a worrying long-term trend, she explained.

One of the problems with climate change, Rumpf said, is that most people are now aware of it, but “the consequences of our actions are decoupled from our daily lives.” Most people do not immediately see the results of the crisis.

“We hear about it, we see numbers, but those facts can seem far away,” she said. “I hope these very striking effects – which are now actually visible from space – might be easier for people to grasp, rather than discoveries about how much carbon dioxide we have in the atmosphere.”

Carbon dioxide certainly plays a role. Mountain regions, which are biodiversity hotspots, are warming about twice as fast as the global average. This warming leads to greening and the subsequent increase in vegetation advances the cycle. Taller and denser plant life in areas where this is not the norm can endanger alpine plant and animal communities and release more greenhouse gases through melting permafrost.

Greening can also prevent snow cover, and less snow impairs an area’s ability to reflect solar radiation – the energy that comes from the Sun back to Earth. An inability to reflect this energy contributes to global warming.

“The snow reflects about 90 percent of that,” Rumpf said. “When we have less snow, we keep more of that energy.”

Alexander Winkel, a postdoctoral researcher at the Max Planck Institute for Biogeochemistry, was not part of this research but also studies how climate change affects vegetation. Beyond greening, there is also browning – this is when plants die, which his research shows happens in tropical regions. Beyond the Alps, greening is well established in the Arctic, a reality some experts say should be considered as an indicator of global climate change.

“Trends in vegetation are now well known to the scientific community but are certainly underestimated phenomena by the public,” he said.

When talking to people about greening in response to carbon dioxide emissions and human-caused climate change, the response Winkler often gets is, “So that’s a good thing, isn’t it? not ? »

Not necessarily, he says. While plants can absorb and store atmospheric carbon dioxide, which can help fight climate change, the other costs are significant.

Rumpf agrees. “It’s also important to remember that carbon dioxide absorbed by plant biomass is not stored for eternity and removed from the system,” she said. “It is recycled and enters the system again. It’s not really gone.

Alpine plants, due to their small size, also play a much smaller role in overall carbon dioxide uptake.

Whereas there are efforts underway to create biodiversity protected areas in the Alps, Rumpf said, major action is needed to slow this trend. Overall, climate change-induced precipitation changes are expected to reduce snow cover by up to 25% in the Alps over the next 10 to 30 years.

“We can try to mitigate these effects on a small scale, but if we don’t change the source of the problem, it’s a pretty small effort,” she said.

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