Scientists, students share findings on ancient beavers, mysterious sea floor bumps and thick winter air

It’s time to start emptying the notebook following the Fall Meeting of the American Geophysical Union, which happened from Dec. 9-13 in Washington, D.C.

More than 25,000 scientists shared their work during those five days. Here is a sampling.

Where have beavers been? Neve Baker of the University of Minnesota uses ancient traces of DNA in pond sediments to determine if beavers have lived in a place. Last year, she found signs that beavers were present 7,500 years ago in a pond within Grand Teton National Park in Wyoming. Beavers don’t live there now.

California Department of Fish and Wildlife officials are interested in stocking some areas with beavers to help restore wetlands and provide more fire resiliency.

Baker hopes to visit Alaska in 2025 and sample northern lakes. Baker would like to try her technique to see when beavers may have been present in extreme northern wetlands thousands of years ago.

A mysterious bump on the Alaska sea floor. Kendal Hobbs of Oregon State University stood by her poster one afternoon with the hope that educated passersby could help her identify a 400-foot lump she and others noticed on the sea floor beneath the Gulf of Alaska.

The bump might be a seamount (an underwater mountain often formed by a volcano), a mound caused by earthquake action, or maybe even debris kicked up by a meteorite strike. She and her colleagues imaged the underwater hill while aboard the University of Alaska Fairbanks research ship Sikuliaq in summer 2024.

Those who visited Hobbs’ poster were also a bit puzzled.

“We have no idea what it is — that’s what makes it a good story,” said Sean Gulick of the University of Texas at Austin.

By the end of several hours talking with passers-by in the massive poster hall at the Walter Washington Convention Center, Hobbs had not come up with an answer for what she calls “Sikuliaq Knoll.”

“Everyone I’ve talked to for the past four hours has a different idea,” she said. “I came away with a lot less clarity.”

Smoke ‘em if you got ‘em. Living in downtown Fairbanks is like smoking a cigarette a day during the town’s worst air-quality days in midwinter.

Winter temperature inversions — in which warmer air sits atop stagnant cold air — create conditions during which Fairbanks air is thick with tiny particles, reported Manabu Shiraiwa of the University of California, Irvine.

Shiraiwa visited Fairbanks in January and February of 2022 to sample the city’s air during a campaign with UAF researchers. Team members felt temperatures of minus 40 as they monitored air outside in downtown Fairbanks. They also measured air inside local homes.

Team members were able to detect when people fired up their woodstoves during extreme cold weather and how particulate matter from cars increased in overall percentage when the temperature warmed. Though not as bad as air quality in urban China, Fairbanks air was worse than most cities in the United States.

“Fairbanks people — even if they were not smoking — were breathing the equivalent of (up to) one cigarette daily,” Shiraiwa said of the worst days.

He also said that indoors often offered no escape due to particles that escaped wood and pellet stoves.

“Indoor air quality can be even worse than outdoors when people are burning wood,” Shiraiwa said.