Snow in the European Alps is melting and invasive plant species are outcompeting native Alpine plants, satellite imagery has shown. Both findings will reinforce climate change, say scientists.
The changes noticed in a new study, which uses satellite data from 1984 to 2021, show that as much as 77 per cent of the Alps has experienced greening, where areas with previously low vegetation have suddenly seen a boom in plant growth.
While the new plants do take a small amount of carbon out of the atmosphere by photosynthesis, scientists say the greening has a much bigger negative effect on climate change, as less of the Sun’s light will be reflected away from the Earth meaning the planet will get warmer.
The Alps are expected to see a reduction in snow mass of up to 25 per cent in the next 10-30 years, according to the Intergovernmental Panel on Climate Change's 2019 report. As the snow melts, there will be more rock falls and landslides, which could have devastating consequences.
The new study shows that the Alps is experiencing snow cover recession that can already be seen from space, which the authors warn will only get worse as time goes on.
A comparison of aerial images of a section of the Western Swiss Alps today and in 1984 © swisstopo
In the changing mountain environments, native Alpine plants have suffered while new species have thrived. This is because the plants specialised to higher elevations have had to focus on long-term living in the Alps, sacrificing the characteristics that could make them more competitive in the short term.
"If you think about a garden, there are always unwanted weeds that spread everywhere because they can utilise resources, like nutrients, very well," said Dr Sabine Rumpf, lead author of the study. "They typically grow fast and produce many offspring, while other plant species are simply outgrown by them because they can’t exploit the resources as fast as the weeds do.
"This is similar to what's happening in mountain environments. High alpine species invest their resources in ‘body armour’ to persist in the long-term – most of them are very long-lived but don’t reproduce very often successfully."
It's unlikely that the Alpine plants could catch up with the non-native species, or adapt to the changing environment, for this reason, said Rumpf. "Evolution is a slow process and only runs its course via sexual reproduction. So, species that reproduce very slowly will thus take even longer to adapt than other species. Some will be able to adapt but, overall, the chances are not very high for the majority."
As greening increases in the Alps, the habitats for many Alpine plant species will disappear entirely.
"The mountains harbour very specialised plant species. Some only grow in snow beds, where the snow persists for a long time in the growing season, while others are adapted to grow in the cracks of rocks or on windblown ridges. If the environmental conditions change, some of these habitats disappear. Other habitats are colonised by fast-growing better competitors and turn unsuitable for these specialists. If the habitats of specialists are disappearing, so will they."
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