In a review published in Communications Earth & Environment, Zhe Han Weng and Annette L. Cowie examined the potential of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More systems for climate change mitigation. Biochar is created by heating biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More in an oxygen-limited environment and can be used as a soil amendmentA soil amendment is any material added to the soil to enhance its physical or chemical properties, improving its suitability for plant growth. Biochar is considered a soil amendment as it can improve soil structure, water retention, nutrient availability, and microbial activity.   More. The authors reviewed 19 studies and found that biochar systems have the potential to remove 1.9-3.3 Pg CO2 equivalent per year.  

The review highlighted that biochar systems mitigate climate change through several mechanisms. First, biochar durably stores carbon in soil, preventing its release as CO2. Second, biochar can reduce emissions of other greenhouse gasses, like nitrous oxide and methane, from soil. Finally, the production of biochar can generate syngasSyngas, or synthesis gas, is a fuel gas mixture consisting primarily of hydrogen and carbon monoxide. It is produced during gasification and can be used as a fuel source or as a feedstock for producing other chemicals and fuels.   More, a renewable energy source that can displace fossil fuels.  

The authors note that previous studies have varied widely in their estimates of biochar’s mitigation potential (0.03 to 11 Pg CO2 equivalent yr-1). They attribute this variation to differences in the scope of studies, definitions of potential, and assumptions about biomass availability. They emphasize the need for new assessments using integrated assessment models to better understand biochar’s potential.  

SOURCE: Weng, Z. H., & Cowie, A. L. (2025). Estimates vary but credible evidence points to gigaton-scale climate change mitigation potential of biochar. Communications Earth & Environment, 6(1), 259.