Permafrost could release more greenhouse gases than previously assumed

Microbes that are currently still trapped in permafrost can apparently also break down polyphenols – carbon compounds that were previously assumed not to be metabolized by soil microbes in the absence of oxygen. The amount of greenhouse gases escaping from thawing permafrost is therefore higher than expected.

Microorganisms that are currently still trapped in the permafrost not only break down certain types of carbon as soon as they thaw, but also compounds that were previously considered toxic, as a new study led by Colorado State University (CSU) shows.

Bridget McGivern, PostDoc at CSU and first author of the study published in Nature Microbiology, specifically investigated whether the permafrost microbes can also degrade polyphenols in the absence of oxygen. She was already working on this topic during her doctoral thesis: “The motivation for a lot of my Ph.D. was how could these two things exist? Organisms in our gut can breakdown polyphenols but organisms in the soil can’t? The reality was that nobody in soils had really ever looked at it,” Bridget McGivern said in a university press release.

In a 2021 study, Bridget McGivern and Kelly Wrighton, associate professor in the Department of Soil and Plant Sciences in the College of Agricultural Sciences, confirmed the theory with soil samples from Sweden.

In the past, some researchers put forward the so-called “enzyme locking theory”, which states that polyphenols could “switch off” microorganisms, trapping large amounts of carbon in the soil. The research team has now shown that the microorganisms in permafrost, which contains little to no oxygen, do break down polyphenols.

When the frozen soil – which contains around 50 percent of the world’s soil carbon – thaws, the microbes become active and begin to utilize the carbon in the soil. And because the microorganisms can break down compounds from the diverse group of polyphenols, the amount of greenhouse gases that escape when the soil thaws is also higher.

In order to quantify how much additional greenhouse gas emissions are released into the atmosphere due to polyphenol degradation, further research must show how fast the metabolism takes place and what could limit the process, according to the researchers.

“The whole point of this is to build a better predictive understanding so that we have a framework we can actually manipulate,” Kelly Wrighton said. “The climate crisis we’re facing is so fast. But can we model it? Can we predict it? The only way we’re going to get there is to actually understand how something works.”

Julia Hager, Polar Journal AG

Link to the study: Bridget B. McGivern, Dylan R. Cronin, Jared B. Ellenbogen, et al. Microbial polyphenol metabolism is part of the thawing permafrost carbon cycle. Nature Microbiology, 2024; DOI: 10.1038/s41564-024-01691-0

More about this topic:

Thawing permafrost could release radon

Heiner Kubny

Climate change not only confronts our world with the release of greenhouse gases such as methane, but also poses an insidious threat due to the release of radon.

New AI-assisted technology is planned to track permafrost in Alaska, beyond

Guest Author

Tracking changes in permafrost can take years and sometimes decades, lags that cannot keep up with the transformations in the rapidly warming Arctic. Now scientists will be developing new technology to track those changes in real time, thanks to a project funded by Google.

Permafrost soils emit more greenhouse gases

Dr. Michael Wenger

The amount of greenhouse gases emitted from the permafrost soils of the Arctic could, in a worst-case scenario, be higher than the amount emitted by the United States in 150 years.