Damning evidence that Beavers affect climate

From the “these inconsiderate rodents must be taxed” department.

The American Beaver in Alaska with his dam. Photo Wikipedia CC/Creative commons

Growing beaver populations have created a large number of new habitats along rivers and ponds. Beaver dams raise the water level, enabling the dissolution of the organic carbon from the soil. From beaver ponds, carbon is released to the atmosphere. Part of the carbon settles down on the bottom, ending up used by plants or transported downstream in the water.

“An increase in the number of beavers has an impact on the climate since a rising water level affects the interaction between beaver ponds, water and air, as well as the carbon balance of the zone of ground closest to water,” says Petri Nummi, University Lecturer at the University of Helsinki, Finland.

Current estimates indicate that beaver ponds range from carbon sinks to sources of carbon. Beaver ponds and meadows can fix as much as 470,000 tons of carbon per year or, alternatively, release 820,000 tons of carbon annually. Their overlapping functions as carbon sinks and sources make landscapes moulded by beavers complex.

Beavers conduct continuous landscaping

A beaver family usually changes territories once every three to five years, but can also stay in the same area as long as twenty years. After beavers abandon their territory, the dam gradually disintegrates and the pond empties. It may fill up again in, say, ten years as a result of returnees. Beaver habitats are in fact undergoing a constant change between terrestrial and aquatic ecosystems.

In the beginning of the 20th century, beavers were hunted to near extinction both in Europe and the central and southern regions of North America. According to estimates, there were 10 million beavers in Europe before the hunting began, out of which only some thousand survived in small, isolated populations across the continent.

Beavers were numerous in Finland as well. For millennia, the species was popular game among ancient Finns before being hunted to extinction towards the end of the 19th century.

“People today obviously have no idea of what pond and stream ecosystems are like in their natural state, since research in the field only began after beavers were taken out of the picture,” says Nummi.

Beaver numbers have incrementally risen, and five years ago the entire European population was estimated to be at least one million specimens. Most of them belong to the original Eurasian beaver species, but, for example, Finland’s current beaver population has its origins in the translocations of American and Eurasian beavers carried out in the late 1930s. Eurasian and American beavers do not interbreed.


The paper: Petri Nummi et al. Beavers affect carbon biogeochemistry: both short-term and long-term processes are involved, Mammal Review (2018). DOI: 10.1111/mam.12134

105 thoughts on “Damning evidence that Beavers affect climate

    • I seem to recall reading somewhere that beaver is not a very tasty repast, but that may depend on how it’s prepared.

      • Before consuming anything, give it a sniff test in order to get an indication if it is edible or not.

      • “may depend on how it’s prepared”

        Or who’s eating it. Bet beavers taste like FOOD to the bears and wolves.

        • Dogs love rolling in the carcasses and love scent of the castor sacs (beaver scent mark their territory). A neighbor of mine made cedar canoes and trapped beaver for a living. Our dog on accasion during trapping seadon would go next door and roll in the carcasses. He’d come back smelling some awful bad. A skunk is slighly worse.

          • My neighbor was Fred Reckards. Famous master canoe builder and he would have my little brother assist during busy times. He had orders 3 years in advance.

            A great man, ( Like his son, Steve). Witty maine style, humourous and always a smile… and would lend a hand anytime.

            Willis here at WUWT would have enjoyed his company.

            Here is a bit of history…

            Fred and Author Templeton were cousins. They both built around the 1920-30’s and maybe a bit into the 40’s.

            Fred lived in Greenville Me. on the shores of Moosehead Lake. He built two canoes, a 15 ft and 20 footer. the 20 was the most popular. It had a flat bottom, a wide 41″ beam, a full entry and high stems. Because it could carry so much it became known as the “Moose River Taxi”. Fred had a good business and had several people working for him.
            A popular sporting good store in Greenville, Sanders Store, rented, sold and repaired Freds canoes. Fred canvased his canoes using the upside down method and that’s what he taught them at the store to use.
            His forms were passed on to Bert Comstock and around 1960 the forms passed to Berts son-in-law Fred Reckards who lived in Rockwood on the shores of the Moose River, just up the lake from Greenville. Fred used mostly fiberglass on his canoes but of course all the earlier ones were canvas.
            Fred Reckards died about 1995 and the forms were sold to a fellow in Old Orchard Beach Me. who thought he would continue the company but it never worked out. A few years ago he was trying to sell the forms but I never did find out if they were sold.

            Author Templeton built his canoes in Rockwood. He just built a 20 footer. His canoe had a rounder bottom, narrower beam and a sharper entry then Freds canoe had. It was also much faster and his canoe was winning races until the late 1960’s when more specialized racing canoes were becoming more popular. Author was very private about his building and did not want people watching him. He as more fussy than Fred and had a pattern for all his planking. He canvased using the rightside up method and would not let people see how it was done.
            His form passed to a local Sporting Camp and then an Insurance company until Doc Blanchard purchased it in 1959. Doc learned how to canvas canoes from Sanders Store using Fred Templetons up side down method. I bet old Author would of had a fit about that! Doc also built a 15 ft canoe but it was off a form he built himself. Docs forms passed to his son in Greenville who is still building off of them.

            So Freds forms went from Greenville to Rockwood to Old orchard Beach.
            Authors forms went from Rockwood to Greenville!

            If any locals were asked to describe the Templeton canoes they would just say they looked a lot like the E.M. white canoes , only larger!

          • I also owned an EM White 21’ cargo canoe that was 80 years old. Served me well on that big lake. I did put a hole (the size of a silver dollar) in it during a sudden storm with 6 foot swells on the north end of Moosehead. It stayed upright and hit the rocky shore.

            The Fix… The hole was on the bottom.

            I gathered some spruce pitch ( spruce gum) and melted it on the campfire. Added dry grass, pliable tiny twigs and applied on both the inside and outside.

            The canoe lasted 10 more years without and further maintenance until a tree came down on it during a wind storm one winter.

            I miss Fred… and would like to thank him and family for their friendship, company and all the rest. I wish society could work together as we all did in that tiny township.

            I take my grandchildren there twice a year. Just got my grandson fly fishing on some world class water there. My granddaughter next year. Her great aunts, (twins) are notoriously great fly fishing. I even admit it…. so does everyone else. We have a bet. Let you all know.

          • That is a perfect description for how Native Americans, rangers, mountain men, etc. patched birch bark canoes. Spruce pitch was also used to waterproof joints and where bark was stitched.

          • Perhaps.

            Trappers tend to hunt multiple species.
            Many of the animal species hunted for their furs have musk glands with many of those animals being far more odiferous than beaver.

            e.g. minks, fishers, ferrets, otters, wolverine, badgers, weasels and the famous Western America polecats are members of Mustelidae.

            While not quite up to Eastern America skunk standards of odor, nevertheless they are quite foul smelling.

            No sane trapper brings the musk glands into their living quarters. Especially if they are married or ever desire to associate with women. These gland contents are used to mask human scents and to attract desired prey; hence they are valuable to trappers.

            I suspect, your dog was getting into that trapper’s musk gland supplies, or discovered where that trapper disposed of punctured glands. Which is usually some distance downwind of living spaces.

            Another possibility, folks following a backwoods lifestyle often make their own buckskins and leathers.
            One part of that process involves soaking the skins until the outer dermis layers decompose and allow the fur to ‘slip’ off the hide.

            This stage of leather making process, the hide’s smell is very rank. And, yes dogs love everything about that stage of hide processing.
            This is also the stage where the tanner stretches the hide for drying, aka rawhide.

            Dogs that locate a soaking hide, discarded wastes or the stretched drying hide, roll in the decomposition waters, slip wastes, or the hide itself and then happily eat as much as they can. Their breath is as rank as their fur afterwards…

            Anyway, beavers, their meat and odors are low on the list of truly offensive smelling animals.

      • I had a few meals of beaver meat prepared by local residents in Labrador. If I hadn’t been told it was beaver, I would have thought it was pork. Not bad at all.

        • try an acidic sauce like tomato, the really cloying fats are neutralized. Never tried it with beaver but works very well on bear.

        A gooey Canadian country specialty comes to life in Queens”

        Like most critters, the young ones can be tender and tasty.
        And like most critters, old beavers collect the flavors of their plants diet.
        Lots of cattail roots and stalks? reasonably neutral in taste.
        Lots of oak tree cambium and bark layers? Expect strong and bitter tannic flavors.

        And, like most critters with musk glands, those glands taint the flavor of beavers, especially older male beaver.

        Early 20th-century chefs used beaver musk to give sweets a vanilla-raspberry flavor

        Of course, they age the musk glands for a few years to allow the nether region odors and off-flavors to dissipate.

        Beavers are a wonderful animal neighbors and very beneficial to other wildlife; i.e., unless one is trying to live near a stream or river without getting flooded.

      • Beaver is actually quite edible, but refrain from eating them in early spring as they often have a strong taste of their winter food – hereabout often aspen wood. Regarding their tail, my father once explained the recommended way of cooking it:
        “Nail to a wooden pole. Drench in diesel oil and set on fire. When fire is out, throw away the tail and eat the ashes.”

    • That’s right DJ. I went to Oregon State University, where the mascot is Benny the Beaver, and the school motto (unofficial?) is “Eat a Beaver and Save a Tree!”. I remember being quite confused by the whole Graduate School experience so I am not sure what this means.

      • Having grown up in Corvallis there are two unofficial mottos though one may not have been in style while you were there. First is “Eat a Beaver, Save a Tree”, second is a bit more vulgar version “Eat a Beaver, F**K a Duck”. For those who don’t know the area, U of O Ducks are less than an hour down the road and there’s quite a rivalry between the schools.

      • I went to MIT, where the mascot is Bucky Beaver. The (definitely unofficial) motto is “The beaver is the engineer of the animal world. The Techman is the animal of the engineering world.”

  1. “Damning evidence that Beavers affect climate”

    Well then, getting rid of both beavers AND capitalistic, conservative Christian old white men = good weather and utopia!

    • When the fashion for top-hats made beavers nearly extinct in the northeast USA, by the start of the twentieth century, there were major floods seen on the Connecticut River at Hartford (which had records going back to the 1600’s.) Since the beaver population began to recover in the 1940’s the major floods have stopped, in part due to “flood control dams”, but also in part because beavers are a natural flood control.

      This of course encourages some whacko tree-huggers to suggest we need to eradicate humanity and protect beavers. That ceases, when the ungrateful beaver fells the tree they were hugging.

      Beavers bring out the stupidity of our legal system, when they flood a suburban neighborhood, which I described in a post back in 2013.


  2. But it should be entirely correct, as it is not people doing it for their own purposes. So counting termite emissions or methane from marshes doesn’t count either.
    It is only wicked humanity that must be controlled!/sarc

    • Interesting, saw some of those in Colorado once. I have an aerial photo of a sizeable beaver tree clearing in the Atchafalya Basin, Louisiana. Apparently its too big to dam. They’re cute when babies though?

      • The largest beaver bam is 2,700 feet long. I came across one surveying the former Loring AFB in Maine. It it an amazing terraced series of dams. The land was given to U Maine. It is ashamed this habitat is not being recorded and studied. There are no known dams like this.

        • There are dams along the Moose River out of Jackman that may be bigger. Some take the better part of a day to pass.

  3. So it was the frontiersmen with all those beaver pelts that caused the last emerging ice age scare of the 70s. Got it.

    • I say let 10000 loose in “the swamp” and turn it into a shallow lake/nature reserve in no time!

      That’ll displace a lot of hot air too!

      And to think Ben Franklin wanted turkeys to be the national critter….

    • Charles,


      South America has a lot of canid species. They could breed native dogs in captivity, spay and neuter them, get them used to beaver meat, then turn them loose in each habitat.

      Then round the dogs up or trap them and let them live out the rest of their lives in zoos.

  4. Okay – I’m not touching this one – WAY too many one-liners. I can only get myself in trouble.

  5. “Current estimates indicate that beaver ponds range from carbon sinks to sources of carbon.” Facepalm.
    Then why do they yammer on about it? The net effect in terms of “carbon” is essentially zero. Not unlike the net effect of CO2 on climate.

  6. So the French fur trappers in the USA artificially caused CO2 to be way too low by nearly exterminating the poor beasts. Now, with limited hunting they are coming back and bringing levels back to the natural balance. So now we need to consider a higher CO2 base to account for the beaver CO2 deficit.

  7. When I pee in the ocean, it has an impact on sea levels.
    That is a true statement, and about as relevant as beavers on climate.

    • “When I pee in the ocean, it has an impact on sea levels.”

      That depends on whether you are standing on the boat or the dock.

  8. Why were they hunted to near extinction? They weren’t being used for hats anymore. Were they edible?

    • Men wore hats until well after WWII. Beaver pelts still make the best hats. I bought a XX (100%) beaver hat in the 1960s just before Stetson went out of business. And it’s still just as good.

      These days you can buy a 400X hat made out of cardboard and rabbit fur. They don’t exactly fall apart in the rain (at least the first rain), but they don’t do well.

  9. “From beaver ponds, carbon is released to the atmosphere.” Really? Are the lefty environmentalists that paranoid about CO2 that something of this magnitude is a problem? At some point their eagerness to identify every possible source of carbon released into the atmosphere becomes schizophrenic. They see a boogeman under every rock.

  10. Your damned if you do and dammed if you don’t. I think.

    Declare an end to plastic straws and you might be rehabilitated. maybe

  11. Beaver dams raise the water level, enabling the dissolution of the organic carbon from the soil. From beaver ponds, carbon is released to the atmosphere. Part of the carbon settles down on the bottom, ending up used by plants or transported downstream in the water

    This is pure gold garbage.

    What on earth is ‘dissolution from the soil’?
    Organic (dead plant as here) material does not dissolve. (in water)
    Dear Prof Numpty, what are *you* made of if not organic material? How’s your dissolving coming along. (Quite well it seems, starting from the top down)

    The dams are Trapping Stuff – ask *anybody* who ever tries to build a conventional dam. The dams are filters, catching stuff that would otherwise float away and be completely lost from that landscape. Stuff that would otherwise go right out into the ocean to be lost forever – or until a Major Vesuvius or 2 blows its top.

    ESPECIALLY, as the pecked out sheep farmer mentions, good at catching sediment & mud.
    Dirt and topsoil.
    *Impossibly* valuable stuff to plants, farmers and The Climate alike.
    The ironing there is Beaut-I-Ful , it was overgrazing by the sheep that created the mud in the first place. haha.
    (You can tell I’ve no sympathy with sheep unless they’re curried)
    Check with (what was) the United Utilities Company in North West England – they wanted sheep fenced off their reservoir catchments to prevent exactly that – silt coming off fields (over) grazed by sheep from filling the things up.

    It was silt, settling out from the flooding river that kept farming alive on the Nile Delta for 7,000 years. Not for much longer now that big dam has gone up and is catching all the mineral and organic goodness that came down the 2 branches of the Nile.
    Especially as selfish money-grubbing brain-deads are growing cotton on that super quality dirt – cotton being THE most nutrient hungry plant known to man, with the one exception of tobacco. Tomatoes in third place.
    Might as well pull up the teak & mahogany floorboards in your house to feed the stove.

    At the bottom of the beaver’s pond, light, temperature and oxygen levels will be low. Hence decomposition (CO2 release) will be very slow. Give it 1,000 years for some peat, maybe 10 million years for some Lignite and 100+ mill for coal, oil and or shale gas.

    Yes people, Erhlich’s prediction IS playing out. Right now as we speak and, numpties & muppets like these are his ‘foot soldiers’
    At *least* one story *every* day here on WUWT are absolute proof of that.

  12. “Current estimates indicate that beaver ponds range from carbon sinks to sources of carbon.”

    Flip a coin and be done with it.

    • Not so marque2. Eurasian beavers are racists, and American beavers are victims of racism.

      Colonizers, spreading their eurocentric views without regard for indigenous traditions and languages. Cultural genocide. Missionaries suppressing native spiritualism (which of course is inherently superior to colonial spiritualism) And worse – cultural appropriation!! Ethnic cleansing!! Smallpox blankets!! Oh, the agony, I can’t go on.

      Or was the American beavers that are the settlers and racists? Darn, which was it again…………….? Can’t remember.

      Canadian beavers are OK though. Polite, well liked, peaceable. No global ambitions.

  13. It’s well known that when beavers find a free- flowing stream, their reaction is “Dam it!”.

    • Funny you mention that. A client of mine who bought the best remote ocean front property in Maine, who works for HP PAID FOR HIS COLLEGE TUITION, trapping local critters. I could not believe my eyes in 2003 that someone that young could do that. It’s a lot of hard work and kids nowadays know nothing about it. He had a family, big acreage and salt water fishing, farm and a clam bed next to deepwater
      that is beautiful and cannot be matched.

      There are winners in this world and this was the best I’ve ever seen. He worked his butt off for it and did very well! Outstanding and glad to help!

      (Remote offgrid)

      Congrats my friend!

  14. Alaska? They can see Russia from there.

    Are we sure that they aren’t colluding with Russia?

  15. One of the benefits of reintroducing wolves to Yellowstone was the return of the beavers which has improved the water table.

  16. For those that believe in the radiant greenhouse effect, beaver ponds create more water surface area which allow more H2O to enter the atmosphere. Molecule per molecule, H2O is a stronger IR absorber than is CO2. So if Beavers actually do affect climate it is because their ponds allow more H2O to enter the atmosphere.

  17. My grandson who lives in Oregon blows up beaver dams on his ranch with Tannerite. His teen-aged daughters take turns shooting the explosive to set it off. The first time, they used too much.

  18. I look forward to observing the discussion between the animal liberationists and the weather alarmists. Should be completely rational and appropriate.

  19. “Beaver dams raise the water level, enabling the dissolution of the organic carbon from the soil”
    Perhaps there is some truth to that. They make water ponds where it should be dry. In our area on the Canadian prairie storing water where it normally wouldn’t exist causes salinity in the soils adjacent to the ponds. For that reason plus the drainage culverts they block, there are local bounties on beaver tails up to 35.00 each. On the plus side they are easy to shoot because of their single minded determination to build and improve their works. Remove a few sticks and sit and wait. Hate to kill an animal just doing what comes natural to it but the destruction they cause is amazing.

  20. 1. Go Beavers!

    2. Bring back the Beaver Hat would solve the problem and improve men’s dress standards (and maybe replace the ubiquitous ridiculous “baseball cap”).

    3. Beavers are great everywhere except in my backyard.

  21. Two injured Inuit hunters huddled for three days with the body of their friend who was killed by a polar bear, four other bears circling their camp.

    “They had to sit tight,” said Rob Hedley, administrator for the hamlet of Naujaat, Nunavut, where the hunters were from.

    “It was pretty scary. They didn’t sleep and they were out there for a while.”

    Nunavut’s second polar bear death this summer sparked widespread outrage Wednesday among Inuit, who feel their lives are being endangered by hunting restrictions imposed by southerners.

    The hunters left Naujaat on the northernmost shore of Hudson Bay on Aug. 21 to hunt narwhal and caribou. They were expected home on Thursday.

    Police said they were notified when the trio hadn’t shown up by Sunday.

    A search began Monday with federal, territorial and local teams. Although rescuers knew roughly where the hunters were headed, search boats were blocked by heavy sea ice.

    The Coast Guard icebreaker Louis St. Laurent joined the search and its helicopter found the hunters early Tuesday about 100 kilometres east of Naujaat near Lyon Inlet.

    “It looks like it was a mother and a cub,” said Hedley. “The mother and the cub were killed.

  22. Not surprising to learn that “Eurasian and American beavers do not interbreed.” They probably have a hard time getting cleared by the TSA.

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