The Alps are ‘turning green’ as global warming takes hold, with the change now clearly visible from space, researchers have said.
Researchers from the University of Lausanne and the University of Basel found that vegetation above the treeline has increased in 77% of the Alps.
The researchers warn that as the Alps become greener, it will create a ‘feedback’ effect where they reflect less light, making global warming worse.
While melting glaciers have become a symbol of alpine climate change, plant biomass above the tree line has increased hugely in the period from 1984 to 2021.
This phenomenon of "greening" due to climate change is already well documented in the Arctic and is now being detected in mountains.
Professor Sabine Rumpf, from the University of Basel, said: "The scale of the change has turned out to be absolutely massive in the Alps."
The Alps are becoming greener because plants are colonising new areas and the vegetation is becoming denser and taller.
The authors show that the increase of plant biomass is primarily due to changes in precipitation and longer vegetation periods as a result of rising temperatures.
"Alpine plants are adapted to harsh conditions, but they're not very competitive," said Prof Rumpf.
As conditions change, these specialised species will lose their advantage and be outcompeted.
She added: "The unique biodiversity of the Alps is therefore under considerable pressure."
In contrast to vegetation, the extent of snow cover above the tree line has only changed slightly since 1984.
The researchers excluded lower regions of the Alps, glaciers and forests.
In the remaining regions, they found that snow cover had decreased significantly in almost 10% of areas.
Professor Antoine Guisan, from the University of Lausanne, said: "Previous analyses of satellite data hadn't identified any such trend.
"This may be because the resolution of the satellite images was insufficient or because the periods considered were too short."
Professor Grégoire Mariéthoz, of the University of Lausanne, said: "For years, local ground-based measurements have shown a decrease in snow depth at low elevation.”
"This decrease has already caused some areas to become largely snow-free."
Prof Rumpf added: "Greener mountains reflect less sunlight and therefore lead to further warming — and, in turn, to further shrinkage of reflective snow cover.”
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