Biochar co-benefits are valued in the voluntary carbon market

Climate mitigation pathways towards global net-zero emissions targets commonly include large-scale deployment of carbon dioxide removals. Investment in novel carbon dioxide removal technologies is currently driven by the self-steering voluntary carbon market. Here we assess whether the upscaling of biochar carbon dioxide removals via voluntary carbon market can deliver sustainable development co-benefits. We use hedonic pricing to estimate how Sustainable Development Goal claims are reflected in biochar carbon credit prices in transactions up to 2024. The results show that biochar carbon credit prices increase by 0.14% for each 1% increase in associated co-benefit claims. Grouping co-benefit claims into environmental, economic, and social pillars reveals that credits with more economic claims tend to be priced higher, while those with more environmental claims tend to be priced lower. Since the market values co-benefit claims, auditing them is critical to verify their genuine contributions and to maintain the integrity of novel carbon dioxide removals. Biochar carbon credit buyers pay for SDG claims, with credits associated with economic and social benefits showing higher prices and those linked to environmental claims lower, in a hedonic pricing study of 171 voluntary carbon market transactions.