The Methodology of Generating Blood-Red Snow in the Alps
Erupts frequently in specific icy terrains, giving the snow a crimson hue. This peculiar occurrence, also referred to as 'blood snow,' can be found in regions like the Alps. A team of researchers is delving into this intriguing phenomenon and forecasts less frequent occurrences in the future.
Snow-loving algae have been discovered not only in lakes but also in snow. A research group spearheaded by Léon Roussel from the University of Grenoble has established this. They've not only pinpointed the primary affected locations but also determined the prerequisites for the algal bloom responsible for the snow's reddish tint.
These algal blooms can manifest in various colors, from red to brown or green, depending on the type of algae. In the Alps, the red pigments are attributed to the green alga Sanguina nivaloides.
Utilizing satellite images spanning five years (from 2018 to 2022), this research team concluded that blood snow is predominantly observed in specific parts of the Alps. These areas include the northern French Alps, the Bernese Oberland, and the Wallis, with lesser occurrences in Austria's Ötztal and Hohe Tauern.
Blood snow predominant at moderate altitudes
Bloom conditions were primarily observed between 1,800 and 3,000 meters, typically on non-steep south and east-facing slopes, and more frequently in June than in other months. Less than 6% of the recorded incidents involved glaciers. The algae appear to exhibit a certain site loyalty, showing consistency in their occurrences.
By analyzing the satellite data alongside meteorological records, the research team identified essential conditions for the blooms: a protracted snowmelt period of at least 25 days and the perpetual presence of water throughout the snowpack. The average snowmelt period was 54 days for the recorded occurrences, with water percolating through the snow for an average of 49 days.
"Liquid water in the snow is crucial for the algae for two reasons," the group explains. "First, nutrients are released when snow melts. Second, it is postulated that snow algae species, including S. nivaloides, migrate during a mobile flagellate cell stage in the water." It also appears crucial that the ground is not permanently frozen, given that blood snow in the Alps is relatively rare above 3,000 meters.
Saharan dust as a nutrient source
Additionally, dust from the Sahara plays a role. This dust, rich in nutrients like phosphorus and potassium, should not be over-abundant or scarce, according to the research team's findings based on their five-year data. Excessive dust can speed up snowmelt.
Climate change in the Alps is not believed to enhance algal blooms, potentially causing increased snowmelt. Instead, with rising temperatures, this phenomenon is more likely to move to higher altitudes, where the affected area is significantly less. If temperatures rise significantly, blood snow in the Alps could become significantly less common in the near future.
The Commission has acknowledged the significant findings of the research team about blood snow, highlighting the crucial role of algal blooms in the reddish tint of the snow.
Based on their analysis, the Commission predicts that the frequent occurrences of blood snow in the Alps may decrease due to climate change, with the phenomenon shifting to higher altitudes.
