Over recent years considerable effort has gone into beaver conservation, due to beavers facing the prospect of extinction. Extinction is partly a legacy of the historic fur trade and then by extensive habitat loss. While beaver numbers are now up considerably, the conservation efforts have led to other, unanticipated, consequences.
Beaver numbers are not simply higher in the traditional locales; beavers have been introduced into new territories, such as in South America.
As more beaver colonies form, the rodents have an adverse effect on the climate by changing levels of methane gas. This happens because beaver colonies are formed in ponds constructed by the beaver dams. These tend to be pockets of shallow water (no more than 1.5 meters high.) Within this oxygen-poor standing water, methane gas levels build up and the gas, because it cannot dissolve in the water, is eventually released into the atmosphere.
On hearing this, social media user Cuger (@CugerBrant) tweeted the question: “What do squirrels, beavers & reindeer have to do with methane emissions?”, before linking to the research. This was followed by wildlife charity DUCinBC (@DUCinBC), who messaged: “Who knew? Beavers’ add 800 million kg of methane to the atmosphere every year.”
According to Professor Colin J. Whitfield (University of Saskatchewan in Canada), compared with 100 years ago, 200 times more of greenhouse gas is released into the atmosphere from beaver colonies. This has come from a study into beaver colonies in Eurasia (the Castor fiber species) and North America (the Castor Canadensis species.)
The research is built on some samples taken and analysed and then through computer modelling. It is estimated that beaver numbers, globally, now exceed 10 million. Beaver dams extend over 42,000 square kilometres and affect 200,000 kilometres of surrounding water.
The model suggests beavers currently contribute 0.80 teragrams (or 800 million kilograms) of methane into the atmosphere. Interviewed by International Business Times, Professor Whitfield suggest this problem not going away anytime soon unless action is taken: “Continued range expansion, coupled with changes in population and pond densities, may dramatically increase the amount of water impounded by the beaver…[this] suggests that the contribution of beaver activity to global methane emissions may continue to grow.”
The research is published in the journal AMBIO (Journal of the Human Environment.) The research article is titled “Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas.”
