Melting glaciers will release huge amounts of microorganisms to the aquatic environment

When glaciers in the Northern Hemisphere shrink as a result of climate change, large amounts of microorganisms will be released to the surrounding environment. This has been established by a research team headed by Ian Stevens, postdoc at the Department of Environmental Science at Aarhus University, in a new research article that has just been published in Nature Communications.

The team behind the research article has studied surface meltwaters from eight glaciers across Europe and North America, and two sites in western Greenland. On the basis of this, the researchers assess that more than one hundred thousand tonnes of microorganisms will be released to surrounding ecosystems as a result of increased melting.

"The study focuses on the number of microorganisms living on glacier surfaces in the Northern Hemisphere, and what happens with them when the glaciers melt. We collected around 1,000 samples from glaciers from Arctic Canada, Svalbard, Sweden, the European Alps and Greenland, and we counted the microorganisms in the samples," says Ian Stevens.

The researchers found that meltwater from more or less all glaciers contained around 10,000 microorganisms per millilitre. This helped the researchers estimate the amount of carbon that risks being led with the meltwater from the glacier surface and into the surrounding aquatic environment.

"In the study, we found that, with a medium climate change scenario with an average temperature rise of around 2.7^oC in 2100, we can expect up to 0.65 million tonnes of carbon to be released from the glaciers in the Northern Hemisphere every year," says Ian Stevens.

In the study in question, the researchers did not study the types of microorganisms contained in the meltwater. According to Ian Stevens, however, it is typically a good mixture of algae, viruses, bacteria and fungi.

"Much of the carbon released from the melting glaciers will end up in the rivers supplied by the glaciers, or in the sea. However, we do not yet know whether the microorganisms can be harmful or beneficial, or what consequences the changes in the carbon supply could have for agriculture using the water from glaciers," he says.

In the coming period, Ian Stevens and the rest of the team of researchers will continue to study meltwater from glaciers in the Northern Hemisphere to learn more about what microorganisms the meltwater contains and how many of them survive transport onwards into the aquatic environment.

Ian Stevens is also affiliated with the Deep Purple project funded by the EU, in which an international team of researchers are studying the microbial processes that contribute to the darkening of the Greenland Ice Sheet.

The research project is a collaboration between Aarhus University, Aberystwyth University, the University of Hertfordshire and six other universities across Europe and North America.