University of Arizona scientists have helped discover a microbe that is set to play a significant role in future global warming. The methane-producing organism was first identified in soils in northern Sweden that were once frozen year-round but have begun to thaw under the effect of globally rising temperatures.
As global warming continues, researchers warn that massive amounts of greenhouse gases from carbon stored in permafrost around the world – which makes up almost a quarter of the Earth's land surface – are likely to be released, further accelerating climate change.
The team made the discovery, published in the journal Nature Communications, by using DNA from soil samples and reconstructing a near-complete genome of the microbe, bypassing traditional methods of cultivating microbes in the lab. The researchers showed the organism and its close relatives live not just in thawing permafrost but also in many other methane-producing habitats worldwide.
"We noticed a bloom of one particular microbial type that comes to abundance in the thawed habitat. This organism just goes crazy." said Virginia Rich, an assistant professor in the UA's Department of Soil, Water and Environmental Science in the College of Agriculture and Life Sciences. "It is very unusual to see that kind of dominance within a microbial community in the soil."
Similar to food in a failing freezer, organic matter locked up in the thawing soils becomes available to microbes. As they consume these organic compounds, microbes release greenhouse gases like carbon dioxide and methane into the atmosphere. A potent greenhouse gas, methane is about 25 times more effective at warming the atmosphere than carbon dioxide. Of all the carbon in the world's soils, about a third is stored in permafrost soils.
"As permafrost thaws, the microbes kick into action and release more greenhouse gas, fueling global warming. It's a strong feedback loop, and overall we get a worse greenhouse gas footprint," said Rich, who has joint appointments in the departments of Ecology and Evolutionary Biology and Molecular and Cellular Biology at the UA. She also is a member of the UA Institute of the Environment.
At the study site, the Stordalen Mire near Abisko National Park in Sweden, just north of the Arctic Circle, the researchers compared intact permafrost, partially thawed permafrost and fully thawed, "boggy" permafrost.
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