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Over the twentieth century, the Alps warmed by 2 degrees Celsius (3.6 degrees Fahrenheit) – twice as much as the northern hemisphere’s average warming.
Now, a research team led by scientists in Switzerland discovered that 77 per cent of land above the Alps’ treeline - the place at which elevation becomes too high for trees but some plants can still grow - has become greener since the mid-1980s.
While more plant growth may seem positive, it could lead to native wildlife being forced out by new species and changes to habitat.
“These high alpine species, they are very well adapted to these harsh climatic conditions and this harsh environment,” Sabine Rumpf, an environmental researcher at the University of Basel and a study co-author, told The Independent.
Some barren areas became green, Dr Rumpf said, but it was also likely that existing plant growth became denser due to changes in temperatures and rainfall, and that species from lower elevations crept upwards.
The team used satellite data to measure changes in land cover across the Alps from 1984 to 2021, according to the study published on Thursday in the academic journal Science.
Using satellite data, scientists were able to detect how much chlorophyll – the material that makes plants green and helps them photosynthesize – is in a given location. The researchers used that information to measure plant growth in the Alps over the years.
Satellite images comparing Switzerland in 2020 (left) verus 2004 (right). Data from Swiss Federal Office of Topography
High-elevation Alpine areas contain unique species and ecosystems that could be at risk as plant growth accelerates. For example, Saxifraga paniculata, a flower with a simple group of white petals, is retreating and “very much on the losing side of things,” Dr Rumpf said.
Some specialized plants, like those growing in areas recently covered by glaciers, could lose out under new conditions, she added.
“These high alpine specialists are the kind of key emblematic species of the European Alps,” Dr Rumpf said.
In theory, more plant growth means more carbon dioxide (CO2) is being pulled from the atmosphere, which would help reduce global heating.
But don’t hold your breath for that silver lining, Dr Rumpf said, as plants at high elevations don’t absorb nearly as much CO2 as places like tropical rainforests, so impact would be limited.
In addition to vegetation, the researchers also looked at snow cover. They discovered some snow cover loss, but that was less widespread than changes in plant growth.
One reason may be how the snow cover was measured. Dr Rumpf noted that their satellite data could only provide information on how much land is covered by snow, not how thick it is.
Earlier research has found that snow across the Alps has been getting thinner over the past four decades.
In addition to hotter temperatures, changes in rainfall and snowfall – also likely driven by the climate crisis – may have influenced plant growth and snow cover.
Further warming could bring even more changes to the Alps, though exactly how is unclear. While snow cover is likely to continue decreasing, Dr Rumpf says, the “greening” they found could turn into “browning” — where vegetation starts to die out as conditions becomes too hot or too dry, for example.
But no matter how it manifests, it’s clear that the climate crisis is likely to transform Europe’s iconic central mountain range.
“What most people picture, I imagine, is the Alps, and the beautiful nature of the Alps, and all those alpine flowers,” Dr Rumpf says.
“And if this process continues, we might lose these species and this environment that we actually attach a lot of our tradition to.”