The world isn’t done blaming beavers for climate change, so there are a few more science articles bemoaning the dam beavers and permafrost. But at least one of them talked to Emily Fairfax yesterday so we’re mighty happy about that. This is from Popular Science.
Beavers might be making the Arctic melt even faster
Carbon pollution is causing all sorts of weird effects on the planet, including dramatic weather shifts and reshuffling ecosystems. Every day brings a new surprise driven by the cascading impacts of warming the Earth. Now, a new study in Environmental Research Letters shows that a warming climate may have unleashed beavers upon the tundra in the Alaskan Arctic—and their activities could be accelerating the loss of permafrost.
In Alaska and Canada, beavers have mostly made their homes in forests. But things are changing. Summers are longer, seasonal winter ice is thinner, and shrubs are increasingly sprouting up, making the tundra an increasingly appealing place for the rodents. In recent years, researchers have documented beavers setting up their dams in these treeless landscapes, and more lakes are now pocketing the tundra.
Okay this part we know. Where’s the inspiring new Emily part?
However, it’s important to note that the research team did not directly link increased permafrost thawing to beaver ponds. More watery surface area across the tundra is known to chip away at permafrost—that’s not in dispute. But Emily Fairfax, an ecohydrologist at California State University Channel Islands, says that you can’t apply that same relationship to beaver ponds. Instead, most beaver-created water bodies tend to be shallow, and thus are more likely to completely freeze over during winter, which would prevent a significant loss of permafrost. In a calculation based on typical beaver dam heights and winter temperatures in the study region, Fairfax argues that the majority of beaver ponds in the study area probably freeze through in winter and “are behaving more like shallow wetlands that go through freeze-thaw cycles just like the active layer of permafrost does.” Adds Fairfax, “The scale of impact the authors imply is overstated.”
Even if beavers are causing some extra melting, it’s hard to say how that would ultimately factor into how much soil carbon is stored or lost. As Fairfax points out, beaver ponds can retain water from thawed permafrost that would otherwise drain away. Dried permafrost soils, meanwhile, are highly flammable—and, if ignited, can release lots of carbon into the atmosphere.
And no scientist is saying we should be mad at beavers, which are known to provide many benefits to their native ecosystems.
