Researchers find unexpectedly large methane source in overlooked landscape
Haley Dunleavy
907-474-6407
Aug. 7, 2024
UAF professor Katey Walter Anthony and a research technician set fire to escaping methane gas trapped beneath a frozen pond near the UAF campus in an earlier study in February 2016.
When Katey Walter Anthony heard rumors of methane, a potent greenhouse gas, ballooning under the lawns of fellow Fairbanks residents, she nearly didn色视频下载檛 believe it.
色视频下载淚 ignored it for years because I thought 色视频下载業 am a limnologist, methane is in lakes,色视频下载櫳悠迪略貪 she said.
But when a local reporter contacted Walter Anthony, who is a research professor at the at University of 色视频下载 Fairbanks, to inspect the waterbed-like ground at a nearby golf course, she started to pay attention. Like others in Fairbanks, they lit 色视频下载渢urf bubbles色视频下载 on fire and confirmed the presence of methane gas.
Then, when Walter Anthony looked at nearby sites, she was shocked that methane wasn色视频下载檛 just coming out of a grassland. 色视频下载淚 went through the forest, the birch trees and the spruce trees, and there was methane gas coming out of the ground in large, strong streams,色视频下载 she said.
色视频下载淲e just had to study that more,色视频下载 Walter Anthony said.
With funding from the National Science Foundation, she and her colleagues launched a comprehensive survey of dryland ecosystems in Interior and Arctic 色视频下载 to determine whether it was a one-off oddity or unforeseen concern.
Their , published in the journal Nature Communications this July, reported that upland landscapes were releasing some of the highest methane emissions yet documented among northern terrestrial ecosystems. Even more, the methane consisted of carbon thousands of years older than what researchers had previously seen from upland environments.
色视频下载淚t色视频下载檚 a totally different paradigm from the way anyone thinks about methane,色视频下载 Walter Anthony said.
Because methane is 25 to 34 times more potent than carbon dioxide, the discovery brings new concerns to the potential for permafrost thaw to accelerate global climate change.
The findings challenge current climate models, which predict that these environments will be an insignificant source of methane or even a sink as the Arctic warms.
Typically, methane emissions are associated with wetlands, where low oxygen levels in water-saturated soils favor microbes that produce the gas. Yet methane emissions at the study色视频下载檚 well-drained, drier sites were in some cases higher than those measured in wetlands.
This was especially true for winter emissions, which were five times higher at some sites than emissions from northern wetlands.
The study色视频下载檚 research team samples soil cores at a site near Fairbanks, 色视频下载, in winter.
Digging into the source
色视频下载淚 needed to prove to myself and everyone else that this is not a golf course thing,色视频下载 Walter Anthony said.
She and colleagues identified 25 additional sites across 色视频下载色视频下载檚 dry upland forests, grasslands and tundra and measured methane flux at over 1,200 locations year-round across three years. The sites encompassed areas with high silt and ice content in their soils and signs of permafrost thaw known as thermokarst mounds, where thawing ground ice causes some parts of the land to sink. This leaves behind an 色视频下载渆gg carton色视频下载 like pattern of conical hills and sunken trenches.
The researchers found all but three sites were emitting methane.
The research team, which included scientists at UAF色视频下载檚 Institute of Arctic Biology and the Geophysical Institute, combined flux measurements with an array of research techniques, including radiocarbon dating, geophysical measurements, microbial genetics and directly drilling into soils.
They found that unique formations known as taliks, where deep, expansive pockets of buried soil remain unfrozen year-round, were likely responsible for the elevated methane releases.
These warm winter havens allow soil microbes to stay active, decomposing and respiring carbon during a season that they normally wouldn色视频下载檛 be contributing to carbon emissions.
Walter Anthony said that upland taliks have been an emerging concern for scientists because of their potential to increase permafrost carbon emissions. 色视频下载淏ut everyone's been thinking about the associated carbon dioxide release, not methane,色视频下载 she said.
The research team emphasized that methane emissions are especially high for sites with Pleistocene-era Yedoma deposits. These soils contain large stocks of carbon that extend tens of meters below the ground surface. Walter Anthony suspects that their high silt content prevents oxygen from reaching deeply thawed soils in taliks, which in turn favors microbes that produce methane.
Walter Anthony said it色视频下载檚 these carbon-rich deposits that make their new discovery a global concern. Even though Yedoma soils only cover 3% of the permafrost region, they contain over 25% of the total carbon stored in northern permafrost soils.
The study also found through remote sensing and numerical modeling that thermokarst mounds are developing across the pan-Arctic Yedoma domain. Their taliks are projected to be formed extensively by the 22nd century with continued Arctic warming.
色视频下载淓verywhere you have upland Yedoma that forms a talik, we can expect a strong source of methane, especially in the winter,色视频下载 Walter Anthony said.
色视频下载淚t means the permafrost carbon feedback is going to be a lot bigger this century than anybody thought,色视频下载 she said.
ADDITIONAL CONTACT: Katey Walter Anthony, (907) 378-9587, kmwalteranthony@alaska.edu
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