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OKIsItJustMe

(19,937 posts)
Wed Jun 22, 2016, 05:18 PM Jun 2016

Cosmopolitan snow algae accelerate the melting of Arctic glaciers

http://www.gfz-potsdam.de/en/media-communication/news/details/article/kosmopolitische-schneealgen-beschleunigen-die-gletscherschmelze-in-der-arktis/
[font face=Serif][font size=5]Cosmopolitan snow algae accelerate the melting of Arctic glaciers[/font]

[font size=3]The role of red pigmented snow algae in melting Arctic glaciers has been strongly underestimated, suggests a study published in NATURE Communications on June 22. White areas covered with snow and ice reflect sunlight; the effect is called albedo. It has been known for quite some time that red pigmented snow algae blooming on icy surfaces darken the surface which in turn leads to less albedo and a higher uptake of heat. 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.

The red snow phenomenon occurs mainly in warm months. During late spring and summer, thin layers of meltwater form on ice and snow in the Arctic and on mountains. Liquid water and sunlight are crucial for the growth of snow algae; over the winter season they fall into a dormant state.

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.

Together with UK colleagues they found 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 leads to a runaway effect: The more glaciers and snow fields thaw the more algae bloom which in turn results in a 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.“



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