The snow season is becoming increasingly shorter in our Alps: in the last century, in fact, the duration of the snow mass has been shortened by more than a month and there has been little snow at all in the past 600 years. All of this has major ramifications, given snow’s key role in ecosystems, as well as, of course, in the economy of our mountains.
Data appeared from one study It was conducted by researchers from the University of Padua and the Institute for Atmospheric and Climate Sciences of the National Research Council (Cnr) in Bologna and is published in the journal Nature Climate Change.
From the kitchen to the lab. Accurate data on the ice sheet has only been collected for a few decades, so scientists need to find other evidence that will allow them to go back in time and reconstruct how the climate has changed. In this study, they used a young pine that grows in mountain pastures and forests, so that it is covered with wind and snow in winter: Juniper vulgaris (Juniperus communis).
We know it mostly for the food uses of its so-called juniper berries (which are actually strobilis, commonly called cones or pine cones), which are an essential ingredient in gin and used to flavor meat dishes and more.
Instead, scientists analyzed its wood to study past snow cover, reasoning that this plant could live for hundreds of years. “When this shrub is found at high altitudes, it has a habit of creeping on the ground, that is, it grows horizontally near the ground, and it can record the duration of snow cover in its growth rings (the circles we see when cutting a tree and which correspond to growth in a single season, so).
In fact, given its height of a few tens of centimeters, its growing season depends a lot on how early it can get out of the white blanket that covers it, ”explains Marco Carrere, forest ecologist at the University of Padua and first author of the study.
The graph shows the evolution of the duration (in days/year) of snow cover over the years. Machine-collected data was only available for a few years (painted in red), so scientists used other methods to obtain data for past centuries.
© Carrer, M., Dibona, R., Prenden, AL et al.
The story in episodes. The scientists expressed measurements of the growth rings of common juniper, and analyzed plants growing at high altitudes in Val Ventina, in the province of Sondrio, with a snowpack permanence model. Bottom line: Today’s snow cover duration is 36 days shorter than the long-term average, a decline not seen in the past six centuries.
Snow in the mountains not only allows us to have fun during the ski week. It is a precious reserve of water that is released in the summer into the rivers flowing downstream (essential to life, even to us humans). It is the “ingredient” from which glaciers are formed.
And it has an impact on the energy balance of our planet: in fact, the white blanket reflects the sun’s rays very well, while the darker soil absorbs more energy and heats up. So the fact that there is snow or a dark floor changes the albedo, which is part of the solar radiation reflected off the surface. And the fact that the Earth’s albedo is decreasing, due to less snow and ice, is another factor contributing to global warming, in a vicious cycle.
Snowflakes love physics. and geometry
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