As summer approaches, the snow turns scarlet red in the French Alps. A mysterious phenomenon, which worries scientists.
As summer approaches, expanses of snow turn red in the French Alps. A phenomenon that the locals nickname the “blood of the glaciers” and which arouse the concern of scientists. They are actually red microalgae that proliferate to such an extent that they end up coloring the snow. They are also present in winter, but less visible due to their number and their green color.
“It is when the solar radiation becomes very strong, from May, that the algae make a shield of red molecules playing the role of sunscreen. This also coincides with the moment when they multiply and offer surreal landscapes on the summits “, explains to Parisian Éric Maréchal, research director at the cell and plant physiology laboratory in Grenoble.
However, the phenomenon has increased in recent years. And it is possible that the increase in CO2 in the atmosphere, which the algae feed on, is the cause. In addition, these microalgae would accelerate snowmelt. “Unfortunately, the red coloring favors the melting of glaciers by removing the albedo effect of snow. It reflects less solar radiation, heats up and melts faster. In areas without glaciers, this shortens the duration of snowfall, with cascading consequences on the supply of dams or agricultural irrigation in the plains “, affirms Éric Maréchal.
These microalgae still have advantages. They are said to be rich in antioxidants and could be of interest in the fight against cell aging.
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