Peatlands, which store a significant portion of the Earth’s soil carbon, are under increasing scrutiny as global temperatures rise. According to Joel Kostka, Tom and Marie Patton Distinguished Professor and associate chair for Research in the School of Biological Sciences at Georgia Institute of Technology, “Peatlands are essential carbon stores, but as temperatures warm, this carbon is in danger of being released as carbon dioxide and methane.” He emphasized the importance of understanding the ratio between these two greenhouse gases due to methane’s higher potency.
Kostka is the corresponding author of a recent study that examines how peatlands produce carbon dioxide and methane. The research, titled “Northern peatland microbial communities exhibit resistance to warming and acquire electron acceptors from soil organic matter,” was published in Nature Communications this summer. The study was led by Borja Aldeguer-Riquelme, a postdoctoral research associate in the Environmental Microbial Genomics Laboratory, and Katherine Duchesneau, a Ph.D. student in the School of Biological Sciences.
The findings are based on over ten years of data from the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment at Oak Ridge National Laboratory in Minnesota. This project enables researchers to heat large sections of wetland environments to observe changes over time.
“Over the past 10 years, we’ve shown that warming in this large-scale climate experiment increases greenhouse gas production,” said Kostka. “But while warming makes the bog produce more methane, we still observe a lot more CO2 production than methane. In this paper, we take a critical step towards discovering why — and describing the mechanisms that determine which gases are released and in what amounts.”
Researchers have long questioned why peatlands generate more carbon dioxide than methane when conditions seem favorable for methane production. Kostka explained: “In both fieldwork and lab experiments, peatlands produce much more carbon dioxide than methane. It’s puzzling because the soil conditions should help methane production dominate.”
To address this question, scientists used advanced genetic analysis techniques—metagenomics, metatranscriptomics, and metabolomics—to investigate microbial activity within warmed peatland samples collected over several years. They discovered that 80 percent of identified organisms were previously unknown at the genus level.
The study found that while microbial activity increased with temperature rises, changes in microbial community composition lagged behind these metabolic shifts. “We found that microbial activity increases with warming, but the growth response of microbial communities lags behind these changes in physiological or metabolic activity,” Kostka said. He added that this does not rule out future changes in wetland communities as climates continue to warm.
Regarding lower-than-expected methane levels, researchers suggest microbes may be breaking down organic matter to access nitrate, sulfate, and metals needed for producing carbon dioxide instead of methane—a process still under investigation.
Kostka noted challenges associated with such research: “Doing this type of integrated omics research in soil systems is still incredibly difficult.” Experimental chambers used at SPRUCE cover about 1,000 square feet each; careful sampling is necessary to avoid depleting available soil material over many years.
“There’s always something new,” Kostka concluded regarding ongoing discoveries about wetland ecosystems’ complexity.
The full study can be accessed via its DOI: https://doi.org/10.1038/s41467-025-61664-7
Funding for this research came from multiple programs within the U.S. Department of Energy’s Office of Science.
