How bacteria and archaea influence one of Earth’s largest carbon stores as it begins to thaw

By | March 18, 2021

Monique Brouillette writes:

For most of human history, permafrost has been Earth’s largest terrestrial carbon sink, trapping plant and animal material in its frozen layers for centuries. It currently stores about 1,600 billion tonnes of carbon — more than twice the amount in the atmosphere today. But thanks to rising temperatures, permafrost is fracturing and disappearing, leaving behind dramatic changes in the landscape.

Scientists are becoming increasingly worried that the thaw will lead to an epic feast for bacteria and archaea that produce carbon dioxide and methane. And although climate models have long accounted for the carbon-emitting capacity of Arctic permafrost and Arctic lakes, the microbial activity within has largely been treated as a black box, changing in sync with the physical properties of the ecosystem, including temperature and moisture. That’s a problem, says Carmody McCalley, a biogeochemist at the Rochester Institute of Technology in New York. “If your model doesn’t get the mechanism right, it’s probably not going to do a great job of making predictions,” she says.

As scientists look more closely at the organisms living in these environments, the findings are beginning to bubble up. The identity of the dominant microbes in transitional permafrost settings can make a difference to the types of greenhouse gas emitted, for example1. The depths of Arctic lakes could be more sensitive to climate change than expected, owing to the types of microbes they host2. And the availability of iron and other nutrients in the soil could accelerate greenhouse-gas production in some locations.

Although there are still unknowns about how the landscape will change in response to warming — and questions such as the role of viruses in the soil remain largely unanswered — gathering data on the microbes is leading to a more holistic view of what’s going on. “It let us see under the hood,” says Virginia Rich, a microbiologist at the Ohio State University in Columbus and the other co-founder of IsoGenie. “In the permafrost system, this is an acutely pressing need, because these systems are thawing before our very eyes.” [Continue reading…]

Print Friendly, PDF & Email