Beavers could engineer riverbeds into promising carbon dioxide sinks, according to a new international study led by researchers at the University of Birmingham.
The new paper, published in Communications Earth & Environment today, has for the first time calculated the carbon dioxide (CO2) emitted and sequestered due to engineering work done by beavers in suitable wetland areas. The research was led by the University of Birmingham, Wageningen University, the University of Bern, and numerous international partners and the study was conducted in a stream corridor in northern Switzerland which has seen more than a decade of beaver activity.
The researchers' findings demonstrate that these beaver-engineered wetlands can store carbon at rates up to ten times higher than similar systems without beaver activity. Over a 13‑year period, the wetland accumulated an estimated 1,194 tonnes of carbon, equivalent to 10.1 tonnes of CO2 per hectare per year.
Dr Joshua Larsen, from the University of Birmingham and lead senior author of the study, said: "Our findings show that beavers don't just change landscapes: they fundamentally shift how CO2 moves through them. By slowing water, trapping sediments, and expanding wetlands, they turn streams into powerful carbon sinks. This first-of-its-kind study represents an important opportunity and breakthrough for future nature‑based climate solutions across Europe."
Beavers are increasingly returning to rivers and other natural landscapes across Europe, following decades of collaborative conservation efforts. The team have found that beavers dramatically reshape how CO2 is stored, cycled, and retained in headwater stream systems, which are the small, upstream beginnings of rivers.
By building dams, beavers flood stream margins, create wetlands, alter groundwater pathways, and trap large amounts of organic and inorganic material, including CO2.
This study suggests that efforts to further rewild beaver populations in suitable wetland areas could have a major benefit, with large amounts of carbon able to be captured, stored, and prevented from re‑entering the atmosphere.
Beavers working as ecosystem engineers
The research team combined high‑resolution hydrological data, chemical analysis, sediment sampling, greenhouse gas (GHG) monitoring, and long‑term modelling to construct the most comprehensive carbon budget ever produced for a beaver landscape in Europe.
Due to the beaver activity within the area, the wetland acted as a net annual carbon sink of 98.3 ± 33.4 tonnes of carbon per year, driven primarily by the removal and retention of dissolved inorganic carbon through subsurface pathways.
However, the beaver-engineered system also showed clear seasonal patterns. During the summer, when water levels receded and exposed sediment surfaces increased, carbon dioxide (CO₂) emissions temporarily exceeded retention - making the system a short‑term carbon source.
Over full annual cycles, the beaver‑driven accumulation of sediments, vegetation, and deadwood resulted in substantial net carbon storage. Notably, methane (CH₄) emissions - which are often a major concern in wetland systems - were found to be negligible, making up less than 0.1% of the carbon budget.
Dr Lukas Hallberg from the University of Birmingham and corresponding author of the study, said: "Within just over a decade, the system we studied had already transformed into a long‑term carbon sink, far exceeding what we would expect from an unmanaged stream corridor. This highlights the enormous potential of beaver-led restorations and offers valuable insights into potential land‑use planning, rewilding strategies, and climate policy."
Implications for future climate management
Over time, carbon is locked away as sediments accumulate and deadwood builds in beaver-built wetlands. Researchers found that this sediment contained up to 14 times more inorganic carbon and eight times more organic carbon than surrounding forest soils. Meanwhile, deadwood from forested areas growing along riverbanks, streams, or wetlands (known as riparian forests) accounted for nearly half of all long‑term stored carbon.
These stores could persist over decades, suggesting that beaver‑modified wetlands act as reliable, long‑duration carbon sinks – so as long as their dams stayed intact.
Dr Annegret Larsen, Assistant Professor in the Soil Geography and Landscape Group at Wageningen University, said: "Our research shows that beavers are powerful agents of carbon capture and adsorption. By reshaping waterways and creating rich wetland habitats, beavers physically change how carbon is stored across landscapes."
When scaled across all floodplain areas suitable for beaver recolonisation in Switzerland, researchers estimate that beaver wetlands could offset 1.2–1.8% of the nation's annual carbon emissions: delivering climate benefits without active human intervention or financial cost.
Led by the University of Birmingham, Wageningen University, the University of Bern, and numerous international partners, the study was conducted in a stream corridor in northern Switzerland which has had over a decade of beaver-activity within it.
As beaver populations continue to expand, further research into understanding their role in shaping future ecosystems, and future carbon budgets, will be crucial.
