Beavers are taking over the Alaskan tundra, completely transforming its waterways, and accelerating climate change in the Arctic.

The changes are so sudden and drastic that they’re clearly visible from space.

As the Arctic tundra warms, woody plants are growing along its rivers and streams, creating perfect habitats for beavers.

As the furry rodents move into these waterways, they make themselves at home by doing what they do best: chewing and carrying wood to build dams, and clogging rapid rivers and streams to make lush ponds.

What was once a thin line of water cutting across the tundra has become a train of bulbous beaver ponds:

comparison in satellite images of a river, taken in 1980 and 2019
An aerial image from 1980 shows a tundra stream on Alaska’s Seward Peninsula flowing in the direction of the blue arrow. A satellite image from 2019 shows how beaver dams have turned the stream into a chain of ponds. Pink arrows point to prominent dams. (Ken Tape et al./Scientific Reports/Worldview satellite/Imagery © 2022 Maxar, Inc.)

“There’s not even a lot of other animals that leave a footprint you can see from space,” Ken Tape, an ecologist at the University of Alaska Fairbanks, told Insider.

“There is one, and they’re called humans. The funny thing is that humans could not get a permit to do what beavers are now doing in this state.”

This swimming, furry rodent’s invasion of the North American tundra is a mixed bag. The beaver ponds create lush oases that could increase biodiversity, but they also play a role in accelerating the climate crisis.

11,000 new beaver ponds

Tape and his colleagues assessed aerial photos from the early 1950s and found no signs of beaver presence in Alaska’s Arctic tundra. The first signs of beavers appeared in 1980 imagery. In satellite imagery from the 2000s and 2010s, the beaver ponds doubled.

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