We have a surprising new “secret weapon” against climate change: beavers

When we think about ways to capture carbon from the atmosphere, we often imagine huge, expensive technology installations; However, nature has its own systems to be able to clean the environment. One of these systems, as a new study has shown, is that beavers are true carbon sequestration machines thanks to the dams and canal systems that these rodents build.

A Swiss experiment. Until now, we knew that humid ecosystems were important, but precise data was lacking to understand why. Now we know that the key was precisely in these animals, as a study has shown published in Nature.

Here the researchers analyzed in detail an 800-meter stretch of a stream in northern Switzerland that had been modified by a beaver colony. What they saw was that the river corridor, after transforming it, acted as a net sink that could retain around 100 tons of carbon per year.

In perspective. These figures are equivalent to trapping 26% of all the carbon inputs that enter that system, so over 13 years the wetland created by the beavers has reached store a whopping 1,194 tons of carbon. In short, this means that the area stores up to 10 times more carbon than similar river stretches where these rodents do not live, with a sequestration rate of approximately 10.1 tons of carbon dioxide equivalent per hectare per year.

How they do it. One might think that carbon is stored in accumulated wood or swamp plants, but the reality is much more complex. The study attributes that more than half of the carbon that has been removed from the environment is trapped below the surface, in the subsoil of the wetland.

Added to this is the burial of organic carbon in the form of particles in the sediments. By flooding the area and slowing the flow, the beavers created the perfect conditions for carbon to settle and be locked underground for the long term.

The methane problem. When we talk about creating new wetlands, any climate expert might raise an eyebrow, since these areas of stagnant water are known to be large emitters of methane, which is one of the gases involved in the greenhouse effect. On top of that, much more powerful than CO₂.

However, the authors of the study also measured this factor and were pleasantly surprised: methane emissions in this system were surprisingly low, representing less than 1% of the total balance. But in addition, the carbon dioxide emissions that came from the sediments were also much lower than the carbon that the system managed to sequester. In this way, it can be concluded that the beaver wetland is a sink, not a source of emissions.

Meeting objectives. The data collected in this Swiss stream opens an exciting door for climate migration policies, as encouraging the return of beavers can dramatically increase the resilience of our riverbanks. In fact, calculations suggest that the recolonization of floodplains by beavers could offset between 1.2% and 1.8% of Switzerland’s annual carbon emissions.

Images | Francesco Ungaro

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