• Editorial

Climate change: the Alps are turning green instead of white

Even if we are slowly approaching the hot summer days, at the very top of the peaks of the Alps should be snow all year round. Vegetation already occupies 77% of the space above the forests and it rains more than snows. What impact does this have on our earth?

The Alps are changing color. There is less and less snow and more and more green. The high temperatures during spring and summer have caused the characteristic white blanket that shelters it during the cold winters to lose volume over the last four decades. In its place, small and large green shoots are now taking up 77% of the space in the mountains above the forest boundary. Although the landscape change that the landscape is undergoing may be pleasing to the eye, the reality is that these rapid and profound changes will have consequences for biodiversity, terrestrial albedo and the availability of a resource as fundamental to life as water.

What is happening in the Alps is what scientists call 'greening'. In other words, the high alpine zone now has the right conditions for many more plants to grow there than in the past. This phenomenon, described by a Swiss research group, is related to rising temperatures and is already occurring in other parts of the world, such as the Arctic.

As the researchers explain in an article published in the journal 'Science', climate change is the cause of this variation of snow. Scientists have been able to ascertain this change in the landscape through the use of satellite images from four decades ago and today. "Climate change is already visible even from space," say the scientists.

Added to this is the fact that the site has reduced its snow cover by almost 10%, which has to do with a change in the way precipitation occurs in the mountains, now more abundant in rain than snow. "Although projections show that precipitation is going to increase in the Alps, the mountain areas are warming up so fast that they are reducing the proportion of precipitation falling as snow," they explain. In fact, there are already forecasts that in 20 to 30 years, the reduction in snow mass will reach at least 25%.

More plants are not always beneficial

This is directly related to the increase of high mountain vegetation, since the growth of plants generates a vicious circle that does nothing to preserve the white layer that covers the mountain range. The greener the soils of this mountain range, the more easily it exchanges heat with the atmosphere. This ultimately alters snowfall patterns, causing the snow to melt faster and reducing coverage.

"Both plant growth and loss of snow cover have consequences on climate," he adds. Scientists do not rule out that the increase in green cover could mitigate climate change in some way - given the increase in plant production - but it is quite possible that on balance, its contribution to the fight against global warming is minimal. Compared to other biomes, vegetation growing in mountains does not function as a major carbon sink, as is the case with more lush forests.

For this reason, the damage to these ecosystems is likely to be much greater than the benefits, as scientists indicate. Climate change will cause the high mountain flora to undergo profound changes in both its composition and functions, affecting the life forms that depend on it. "It could generate large-scale structural changes throughout the European Alps," they outline in the article.

Change has already begun

The loss of snow, meanwhile, can have negative repercussions on the Earth's albedo (amount of light reflected from a surface), as well as on the economy, recreational activities and the supply of drinking water. First, the decrease in white cover will cause a change in the Earth's albedo, as the mountains will no longer reflect part of the sun's rays back into the atmosphere.

Instead, the Alps will become heat sinks, leading in turn to higher temperatures in the area. This problem could grow even more if the permafrost thaws, since it could release greenhouse gases, as well as generate landslides or large landslides in the mountains.

On the other hand, "glaciers and snow provide half of the world's water resources," say the researchers, who insist that this progressive loss of snow will be coupled with other problems, such as drought, which will deepen the problems of supplying water to future societies.

With textile tarpaulins against melting

Textile tarpaulins can be used to protect parts of glaciers from too much solar radiation. The first attempts to protect glaciers with tarpaulins began as early as 1993 on the Zugspitze in southern Bavaria. This successful method of preserving snow and ice surfaces in the Alps has already spread to Switzerland. Evaluations of aerial photographs have shown that the ice melts about 60% less under the tarpaulins than without them. The melting of the glaciers can be slowed down, but not stopped. In addition, the covering is associated with a large financial outlay, among other things.

Protecting our glaciers from melting and erosion with tarpaulins is a method that has been tried and tested for decades, but it is very costly. However, the fundamental problem of global warming should not be ignored. If temperatures remain the same or even rise in the coming years, the temporary solution of covering glaciers will no longer be sufficient.

baseline study: https://www.science.org/doi/10.1126/science.abn6697

Huss, M.; Schwyn, U.; Bauder, A.; Farinotti, D., 2021: Quantifying the overall effect of artificial glacier melt reduction in Switzerland, 2005–2019. Cold Regions Science and Technology, 184: 103237 (12 pp.). doi: 10.1016/j.coldregions.2021.103237