According to a research released Thursday, the Alps' famed snow-capped summits are rapidly vanishing and being replaced by plant cover, a process known as "greening" that is projected to hasten climate change.
The study was based on 38 years of satellite images covering the whole iconic European mountain range, and was published in Science.
"We were very surprised, honestly, to find such a huge trend in greening," said first author Sabine Rumpf, an ecologist at the University of Basel.
Greening is a well-known phenomena in the Arctic, but it had not been firmly documented in hilly places until today.
Researchers predicted similar impacts since the poles and mountains are both warming faster than the rest of the earth.
To remove areas utilized for agriculture, the scientists looked at locations at 1,700 meters (5,600 feet) above sea level. Forested regions and glaciers were also left out.
Snow cover was no longer present in summer over approximately 10% of the region investigated, according to the data, which spanned the years 1984–2021.
Satellite photographs can only confirm the existence or absence of snow, according to Rumpf, but the first consequence of warming is to lower the depth of the snowpack, which is invisible from space.
Second, the researchers used wavelength analysis to determine the quantity of chlorophyll present to compare the amount of vegetation present, and discovered that plant growth rose in 77 percent of the zone analyzed.
Vicious cycle
Plants begin to develop in previously uninhabited places, they grow taller and more thickly as a result of favorable circumstances, and lastly, certain species that ordinarily exist at lower altitudes migrate to higher elevations.
"It is climate change that is driving these changes," Rumpf explained.
"Warming means that we have longer vegetation periods, we have more benign conditions that foster plant growth, so plants can just grow more and faster," she noted.
"The warmer it gets, the more precipitation falls as rain rather than snow," says the author.
There are also a number of negative outcomes.
For starters, melting snow provides a significant portion of drinking water. If water is not kept as snow, it evaporates more quickly through rivers.
The habitat species that have evolved to the alpine environment are thus disturbed.
The loss of snow has a negative impact on the region's tourist sector, which is a major economic engine.
"What we kind of tend to forget is the emotional aspects of these processes that the Alps are like a very iconic symbol and when people think about Switzerland, it's usually the Alps that they think about," Rumpf explained.
While alpine greening may boost carbon sequestration, the researchers suggest that feedback loops are more likely to result in exacerbated warming and permafrost thawing.
Snow reflects roughly 90% of solar radiation, whereas plant absorbs considerably more and radiates the energy back as heat, speeding up warming, snow melt, and the growth of additional vegetation: a vicious cycle.
From green to brown?
The Alps' future is impossible to forecast with accuracy.
"In terms of snow, it's pretty straightforward," Rumpf added. "I would expect the snow cover to disappear more and more, especially at lower elevations."
For the time being, another phenomena known as "browning" – in which the ground is no longer covered by snow or plants – has only been observed in less than 1% of the study area.
This is far less than what has been observed in the Arctic and Central Asian highlands.
It is fuelled by two factors: a rise in intense rain events followed by droughts, as well as a decrease in water accessible to plants due to yearly snowmelt.
"We do not know for the future whether browning is going to occur more and more," Rumpf said, adding that he intends to replicate his findings in a few years.
