Global warming is turning snowy, white Alps green, study reveals with satellite images from space

The growing impact of the climate crisis on the European Alps can be seen from space, with the snowy mountains appearing increasingly green instead of white, according to a new study.

In the study, published in the peer-reviewed journal Science on Thursday, researchers used high-resolution satellite data to show that, since 1984, vegetation above the treeline has increased by 77% across the Alps. Meanwhile, snow cover has declined by a significant 10%.

“The scale of the change has turned out to be absolutely massive in the Alps,” Sabine Rumpf, lead author of the study and assistant professor at the University of Basel, said in a press release.

The researchers in Switzerland, the Netherlands and Finland identified the rise in vegetation as a phenomenon called "greening," a consequence of climate change that has previously been documented in the Arctic.

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While there could be some positive impact for increased plant growth in the Alps, such as carbon sequestration, the study notes that it's "unlikely to outweigh negative implications" – including habitat loss, challenges in water availability, thawing permafrost and further warming.

“Alpine plants are adapted to harsh conditions, but they’re not very competitive... The unique biodiversity of the Alps is therefore under considerable pressure," Rumpf stated. "Greener mountains reflect less sunlight and therefore lead to further warming – and, in turn, to further shrinkage of reflective snow cover."

The greening in the Alps was "driven by climatic changes during summer" and predominantly found in warmer areas. In contrast, the decline in snow coverage "peaked at colder temperatures" due to changes in precipitation, the study said.

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In addition to the concerning greening, the researchers stressed the significance of the 10% decrease in snow coverage.

“Previous analyses of satellite data hadn’t identified any such trend,” Antoine Guisan, a senior author of the study and professor from the University of Lausanne, said in the press release – while also noting that earlier satellites images may have had insufficient resolution or looked at time periods that were too short.

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“For years, local ground-based measurements have shown a decrease in snow depth at low elevations,” added Grégoire Mariéthoz, also a senior author and professor from the University of Lausanne. “This decrease has already caused some areas to become largely snow-free.”