Thawing permafrost in Gates of the Arctic National Park in Alaska. C.Ciancibelli / NPS
As global temperatures rise, scientists warn that thawing Arctic permafrost is releasing an alarming amount of methane — a greenhouse gas 25 percent more potent than carbon dioxide — into the atmosphere. Now, a new study published in the journal Nature Climate Change has discovered a type of methane-oxidizing bacteria living in upland Arctic soils that could potentially offset some of these emissions.
The findings of the new research, led by scientists at Purdue University in Indiana, indicate that net greenhouse gas emissions from the Arctic may be much smaller than previously modeled due to the increased productivity of a type of bacteria known as high affinity methanotrophs, or HAMs. “This group of bacteria utilizes atmospheric methane as an energy source,” Qianlai Zhuang, lead author of the study, said in a statement. “The emissions from wetlands will potentially be quite large, but if you consider the uplands, then the area-aggregated net emissions will be much smaller than previously thought.”
Organic-rich soils, including permafrost, comprise only 13 percent of land area in the Arctic and are the major source of methane emissions. The remaining 87 percent of the region is dominated by the mineral-rich soils that support HAMs. The scientists argue that their findings may explain why observed methane emissions have averaged 5 to 10 gigatons less per year than climate models predicted.
The researchers’ new biogeochemical model incorporates the role of HAMs and simulates findings closely resembling observed trends in the Arctic. Even though these HAMs will help to curb some of the emissions from thawing permafrost, the scientists warn that Arctic emissions will increase by the end of the century, as shown in other studies.
—Humna Sharif
