Glacial microbes affect albedo

Microbes drastically reduce the surface reflectivity of glaciers and have a non-negligible impact on the amount of sunlight reflected into space suggests the first ecological study of an entire glacier. The University of Leeds-led research will help improve climate change models that have previously ignored the role of microbes in darkening the surface of the Earth. Observing how life is able to survive in such an extreme temperature could have important implications for the search for life on distant worlds such as Jupiter’s moon, Europa. The three-week study, which also included the University of Bristol, was carried out on the Mittvakkat Glacier in south east Greenland during 2012, the hottest summer and therefore fastest melting season for 150 years. “Our timing was serendipitous, as it meant we were able to see changes in the microbial processes over an extremely fast melting season and observe a process from start to end across all habitats on  a glacier surface,” said Stefanie Lutz, a PhD student in Leeds’ School of Earth and Environment. “This is the most comprehensive study of microbial communities living on a glacier to date.” The research, published in FEMS Microbiology Ecology, showed that compared to pure snow and ice, the reflectivity or albedo of the glacier can be reduced by up to 80% in places where coloured microbial populations – snow algae, bacteria, fungi and even invertebrates – are extremely dense, leading to the darkening of the glacier surface. “Previously, it was assumed that low albedo, which is most often measured from satellites, was primarily due to soot or dust,” said Professor Liane Benning, co-author of the study and also from Leeds. “However, our research provides a first, ground-based measure for the microbial contribution to albedo.” “We have shown that albedo is strongly affected by and dependent upon the development and dominance of microbial communities. In future climate scenarios, where even more melting is predicted, it is crucial that we are able to better discriminate between all factors affecting albedo.” Variations of algal communities cause darkening of a Greenland glacier