Most biomass transformation processes — e.g. combustion, pyrolysis, or gasification — result in the direct emission of some portion of the carbon originally contained in the biomass feedstock. Quantifying emissions from biomass transformation supports the assessment of how efficiently a CDR process converts biomass into long-term carbon storage or useful co-products. Biomass carbon lost during biomass transformation be estimated by comparing the mass of CO₂ that is captured for durable storage to the mass of carbon contained in the biomass feedstock. If the transformation process produces other carbon-containing products, such as syngas, tar, or char, we recommend the embodied carbon be conservatively classified as “emitted” unless the product has a clearly defined path to durable storage.