“Microbial gardens” reduce the amount of heat reflected back into space by ice sheets

The first ecological study of an entire glacier has found that microbes drastically reduce surface reflectivity and have an impact on the amount of heat available to warm our planet.

The new research lead by the School of Earth and Environment academics finds a “microbial garden” of life flourishing in the ice. These microbe and algal material act to darken the ice surface and thus limit its ability to reflect the sun’s rays back into space.

The sun is the main source of energy for the Earth. A lot of the it’s energy is reflected back into space by the polar ice caps thanks to their white reflective surface. This acts against the effects of greenhouse gases, which trap the sun’s energy within the atmosphere and act to warm the planet.

However, if large parts of the ice are darkened by microbial activity then the amount of sunlight reflected back into space, and thus not involved in warming our planet, has previously been overestimated.

Microbes such as algae affect the ability of ice to reflect heat back into space.

Microbes such as algae affect the ability of ice to reflect heat back into space. Source: Wikimedia Commons

The new research shows that, compared to pure snow and ice, the reflectivity of a glacier (known as the “albedo”) can be reduced by up to 80% in places where coloured microbial populations are extremely dense, leading to the darkening of the glacier surface.

Current climate change models do not include the effects of microbes in model simulations and are likely to underestimate the severity and degree of climate change expected over the next century.

 

Professor Liane G. Benning from the School of Earth and Environment at the University of Leeds and co-author of the study, said: “Previously, it was assumed that low albedo, which is most often measured from satellites, was primarily due to soot or dust. 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.

Read the full study here:http://onlinelibrary.wiley.com/doi/10.1111/1574-6941.12351/abstract

 

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