When thawing permafrost releases greenhouse gas
There is hardly any other region where climate change is as noticeable as in the Arctic. At the Arctic Science Summit Week 2023, which is currently taking place at the University of Vienna, 700 international Arctic researchers are putting their heads together. One of them is Andreas Richter from the University of Vienna: he and his team experienced the explosive nature of the topic at first hand a few months ago during field research in the Canadian Arctic. Read more in the guest article.
Arctic Science Summit Week 2023
From 17 to 24 February 2023, 700 scientists from all over the world are meeting for the annual Arctic Science Summit Week (ASSW); this year's venue is the main building of the University of Vienna. The discussion agenda includes the clearly noticeable effects of climate change on the Arctic and the consequences for the rest of the world.
The networking meeting is organised by the International Arctic Science Committee (IASC), hosted by the Austrian Polar Research Institute (APRI), which also includes numerous scientists from the University of Vienna.
This year's ASSW Science Symposium (21-24 February) is dedicated to the topic "The Arctic in the Anthropocene" – researchers, students and representatives from politics and economy are invited to discuss the burning issues of polar research.
Greenhouse gases that enhance climate warming
The reason for this lies in the processes that are triggered by thawing. Trapped in the permafrost are dead plant remains and humus, and thus, also organic carbon and nitrogen. Permafrost soils hold one of the world's largest pools of organic carbon and global nitrogen. When the soils and soil-ice mixtures thaw, microbes become active and break down these compounds. As a result, they produce greenhouse gases that enhance climate warming: carbon dioxide (CO2), methane (CH4), but also nitrous oxide (N2O). Nitrous oxide is a greenhouse gas with about 300 times the warming potential of CO2. Microbes produce it from nitrogen released during the decomposition of organic material. However, it is not yet known exactly how these processes take place in thawing permafrost.
In order to get a realistic picture of which processes the microbes trigger in the thawing Arctic soil and how these processes not only boost climate change, but also affect the concrete living situation of the local people in the long term, the researchers had to conduct experiments directly on site and prepare the soil samples for further analyses. "We thawed some of the soil samples over several days to simulate a natural thawing process. Then we added proteins with labelled nitrogen to them and incubated them in airtight containers,” Nicolas Valiente Parra explains. "After a few days, we then sampled the greenhouse gases produced and obtained extracts from the soil samples to determine which compounds the organic material had been converted to and which microorganisms were responsible for it.” These samples were brought back to Vienna and will be analysed in the laboratories of the Centre for Microbiology and Environmental Systems Science. "We will use different analyses to determine what the microbes did with the nitrogen and then we will also know, among other things, how much nitrous oxide they have produced", Valiente Parra says.
Several dozen kilograms of samples
The researchers collected about 50 drill cores with frozen Arctic soil, as well as a large number of plant, water, and soil samples in the Arctic. To Vienna they brought back not only the gas samples and soil extracts obtained from them. The Viennese ecosystem researchers had several dozen kilograms of samples in their luggage. A good half of it is frozen soil: large pieces of frozen earth, each weighing about seven kilograms. "In cooperation with the GFZ Helmholtz Centre Potsdam, we will simulate freeze and thaw cycles in these soil samples over several months in a special incubator set up by our colleagues in Potsdam," explains Nicolas Valiente. "In this way, we want to simulate and trace how the processing of nitrogen in Arctic soils takes place over the course of the seasons.” The researchers hope that this will enable them to further investigate the possible feedback effects between the thawing of permafrost soils and climate warming.
This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101024321.