Study: Beavers becoming more prominent source of greenhouse gases in Arctic

A new report shows the rodents are increasingly contributing to the rate of methane being released into the atmosphere
Published: Sep. 12, 2023 at 7:35 AM AKDT
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ANCHORAGE, Alaska (KTUU) - A study published this summer and headed by University of Alaska Fairbanks researchers points to beavers having an increasing role in greenhouse gas production in the Arctic.

The report, published in the journal Environmental Research Letters, links Arctic beavers to rising rates of methane gas in the region.

“Beavers are colonizing in the tundra,” UAF Research Professor Ken Tape said. “They’re moving from the forest into the tundra regions in western and northern Alaska, which is pretty exciting, just scientifically, and people out in those communities find it pretty radical.”

Researchers with UAF’s Geophysical Institute, including Tape, maintain the study is the very first to link new beaver ponds to an increase in methane gas emissions.

The identification of beavers as another source of methane is also important because of the gas’ role as a potent greenhouse gas, noted in the report as about 25 times more powerful than carbon dioxide when it comes to trapping heat within the earth’s atmosphere.

The report, citing the U.S. Environmental Protection Agency, also shows methane accounts for about 20% of greenhouse gas emissions around the world.

The team at UAF focused on an area of approximately 166 square miles in the Lower Noatak River Basin, in the northwest part of the state. The crew used imagery from space to help figure out exactly how beavers are affecting the area.

“We’ve got beavers moving into the Arctic, and we’ve got all these ponds,” Tape explained. “The reason we know beavers are moving into the Arctic is, they make a footprint that you can see from space, and you know that there’s beavers there, right? So, from space, we mapped over 10,000 beaver ponds in the Alaska Arctic.

“We mapped all of these beaver ponds, creek by creek, slough by slough,” he continued, “and so now, we’ve got this map of beaver ponds, and we’ve got this new tool that shows us where methane is being released on the landscape, and if you overlay those two things, you can see that there’s a greater chance of these methane emissions around beaver ponds.”

The methane hot spots, as Tape called them, are “preferentially associated with beaver ponds,” which are flooding areas of tundra and melting permafrost in those areas.

Rod Boyce, also of UAF, broke the paper down by starting with the creature’s propensity for constructing dams.

“Beavers, as everyone knows, like to make dams,” Boyce wrote. “Those dams cause flooding, which inundates vegetation and turns Arctic streams and creeks into a series of ponds. Those beaver ponds and surrounding inundated vegetation can be devoid of oxygen and rich with organic sediment, which releases methane as the material decays.”

As for the technology used by researchers to map the release of methane, it’s a process called airborne hyperspectral imaging. In this case, it comes from the National Aeronautical and Space Administration’s Arctic-Boreal Vulnerability Experiment program and allows for expanded visibility, far beyond the capabilities of the naked eye.

“This is kind of where the magic is,” Tape said. “Our eye looks at things, daily, in three bands — red, yellow and blue — and from that, we put together the colorful world that we see. But these instruments look down from an airplane or from space in a hundred different bands, so they’re looking at all different parts of the electromagnetic spectrum, and then you can combine them in ways that you can see things like methane, for example.”

Other co-authors include research assistant professor at the UAF Institute of Northern Engineering Benjamin Jones, along with a group from the National Park Service and NASA’s jet propulsion laboratory, all of whom are listed on the full report.