Beaver activity in the Arctic is linked to increased emissions of the greenhouse gas methane
The climate-driven advance of beavers into the Arctic tundra is likely to release more methane — a greenhouse gas — into the atmosphere.
Beavers, as everyone knows, love to build dams. These dams cause floods that submerge plants and turn Arctic streams and streams into a series of ponds. Beaver ponds and the submerged vegetation surrounding them can be devoid of oxygen and rich in organic sediments, which release methane as the material decomposes.
Methane is also released when permafrost, rich in organic matter, thaws as a result of heat carried by circulating water.
A study linking Arctic beavers to an increase in methane emissions was published in July environmental research letters.
The lead author is Jason Clark, a former postdoctoral fellow at the University of Alaska Fairbanks Geophysical Institute. Research professor Ken Tip, also of the Geophysical Institute, was Clark’s advisor and co-author. Other co-authors include Benjamin Jones, research assistant professor at the UAF Northern Engineering Institute; and researchers from the National Park Service and NASA’s Jet Propulsion Laboratory.
Tip has conducted extensive research on the northward migration of beavers and their resulting impact on the Arctic environment.
“What we found is that there are a lot of methane hotspots right next to the ponds and they start to decrease as you move away from the pond,” he said.
The new study is the first to link large numbers of new beaver ponds to methane emissions at the landscape scale. This suggests that engineering beavers in the Arctic will at least initially lead to increased methane release.
“We say ‘tentatively’ because that’s the data we have,” Tipp said. “What the long-term ramifications are, we don’t know.”
As a greenhouse gas, methane is 25 times more powerful than carbon dioxide at trapping heat in the Earth’s atmosphere.
It is responsible for about 20 percent of global greenhouse gas emissions, according to the US Environmental Protection Agency. The agency says human activities have doubled atmospheric methane concentrations over the past two centuries.
The new research focused on 166 square miles of the Lower Noatak River Basin in northwest Alaska. Data were acquired by airborne hyperspectral imaging through NASA’s Arctic and Arctic Vulnerability Experiment Program.
Hyperspectral cameras image an area with hundreds of wavelengths across the electromagnetic spectrum, including many that are not visible to the human eye. This is different from other cameras, which usually only shoot in the primary colors of red, green, and blue.
The researchers compared the location of methane hotspots to the locations of 118 beaver ponds and a number of nearby unaffected streams and lakes. They analyzed an area up to about 200 feet from the perimeter of each body of water and found a “significantly greater” number of methane hotspots around beaver ponds.
“We have these datasets that overlap to a large extent, in space and often in time,” Tip said. “It’s kind of a simple design based on a new tool.”
Additional research into the relationship between beaver migration and methane emissions in the Arctic will be conducted next year.
Jason Clark et al. Do beaver ponds increase methane emissions along Arctic tundra streams? environmental research letters (2023). doi: 10.1088/1748-9326/acde8e
Provided by the University of Alaska Fairbanks
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