Hunt for the red alga that melts glaciers. And scientists are asking tourists for help: “Send us your photos” – time.news

by time news
from Carlotta Lombardo

The species increases solar radiation and endangers the keeping of the snowfields. In the field of the Tridentine Alpinistic Society, Cnr and Bicocca: a mapping to save Presena, Gavio and Stelvio

A task force of scholars to map the red snow, a summer phenomenon caused by the formation of a unicellular alga that decreases the light reflected on the glaciers by increasing the solar radiation absorbed by the snowfields. A plot that, according to scientists, accelerates the melting of the Presena, Gavio and Stelvio glaciers in Trentino. The scholars of the Tridentine Mountaineering Society, the National Research Council and Bicocca University of Milan are already at work, but to complete their task they asked for the help of hikers asking them to send photos and videos, essential to understand where the seaweed is most striking. The phenomenon until now had been studied in Greenland – let the Tridentine Mountaineering Society know -. For the first time in Europe, researchers from the Milanese university have put our glaciers at risk of retreating under the lens. The melting of glaciers and ice caps today considered a symbol of climate change. Many complex mechanisms are involved in ice melting and, among these processes, surface darkening due to organic material on bare ice has recently received attention from the scientific community. The presence of microbes on glaciers has been shown to reduce the albedo of the ice and favor its melting.

The project

But what does the project consist of? The project involves the mapping of snow algae during the melting period in a high altitude basin in the Brenta Dolomites – explains Biagio Di Mauro of Cnr -. Seasonal snow represents a fundamental water resource in mid-latitudes. In the last few decades there has been a decrease in the duration of the snow season in the Alps, induced by late autumn rainfall and early melting in spring. The mechanisms that regulate snow melt are complex and depend on both meteo-climatic and geomorphological parameters. The optical properties of snow play a fundamental role in seasonal melting. In fact, darker snow absorbs more radiation and therefore melts faster. In addition to atmospheric impurities, such as Saharan dust, particles of biological origin can also cause a decrease in the reflectivity of the snow and therefore modify its melting processes. The most relevant biological particles are snow algae – concludes Di Mauro -. These organisms are able to survive in the snow and give it a reddish color during the melting months. The impact of these organisms very little studied and not included in the main snow models.

The red snow of the Arctic

The algae of the red snow act as an accelerator for the melting of Arctic glaciers, a phenomenon already highlighted in 2016 by a study by the GFZ – Helmholtz Center in Potsdam, published in Nature Communications. The phenomenon caused by the presence at high altitudes and in the polar regions of unicellular organisms, of the same class as green algae. The pink to red coloration due to carotenoids and the protection mechanism adopted by the algae spores for the ultraviolet rays of the sun. The red color also absorbs heat and provides the algae with liquid water when the snow melts. The presence of this pigmentation affects the ability of snow and ice to reflect sunlight (the effect called albedo). The algae in fact darken the surface of the snow and contribute to a greater absorption of heat. According to the researchers – who analyzed samples from Greenland, Iceland and the Svalbard Islands – the red snow reduces albedo by at least 13% during the summer season. An important effect that must be taken into account in future climate models.

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August 7, 2021 (change August 10, 2021 | 11:15)

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