The climate-driven advance of beavers into the Arctic tundra is causing more methane release. Their dams cause flooding, inundating vegetation and turning Arctic streams and creeks into a series of ponds. These ponds and surrounding inundated vegetation can be devoid of oxygen and rich with organic sediment, releasing methane as the material decays. And now there are lots of methane hotspots right next to the ponds.
www.uaf.edu/news/beaver-activity-in-the-arctic-increases-emission-of-methane-greenhouse-gas.php