Arctic Snow Turns Red

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Scientists have taken a look at the role of red pigmented snow algae in increased melting of ice in the Arctic and have found that this algae is playing a rather aggressive role compared to previous estimates and that it is a factor that can’t be ignored.

In a study published in Nature Communications, scientists have shown that the algae is causing the snow to become red and this in turn is causing less sunlight to be reflected – meaning that the snow is taking up more heat and this is effectively causing increased melting. The areas of the polar regions which are covered with snow and ice reflect sunlight and this effect is called albedo.

The reddening of ice causes higher uptake of heat from the Sun and this causes more melting. The new study by Dr. Stefanie Lutz, postdoc at the German Research Centre for Geosciences GFZ and at the University of Leeds, shows a 13 per cent reduction of the albedo over the course of one melting season caused by red-pigmented snow algal blooms. “Our results point out that the “bio-albedo” effect is important and has to be considered in future climate models”, says lead author Stefanie Lutz.

During the warmer months, there is noticeable increase in the algae. This is because there are thin layers of meltwater on the ice and snow in the Arctic and because water is primary requirement for growth of algae, they are more abundant in summer than in winter.

In their study, the team led by Stefanie Lutz and Prof. Liane G. Benning investigated the biodiversity of snow algae and other microbial communities using high-throughput genetic sequencing. They took about forty samples from 21 glaciers in the Pan-European Arctic. The sampling sites ranged from Greenland over Iceland and Svalbard to the north of Sweden.

Researchers found during the course of their study that there is a high biodiversity within the bacteria, depending on the locations they lived, whereas the biodiversity of the snow algal communities was rather uniform. In other words: Throughout the Arctic regions, it is most probably the same algal species that cause red snow and thus accelerate melting.

The blooming of algae leads to a runaway effect – the more heat the glaciers and snow fields trap, the more ice melts and more algae bloom occur which in turn causes darkening of the surface which again accelerates melting. Liane G. Benning, head of the GFZ’s section “Interface Geochemistry”, says: “Our work paves the way for a universal model of algal-albedo interaction and a quantification of additional melting caused by algal blooms.”

For years, “bio-albedo has been a niche topic”, says Daniel Remias, biologist at the Fachhochschule Wels, Austria. The snow algae specialist comments on the study: “For the first time ever, researchers have investigated the large-scale effect of microorganisms on the melting of snow and ice the Arctic.”

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