Technical Bulletin No. 1015: A Review of Biomass Carbon Accounting Methods and Implications

When performing greenhouse gas inventories, product carbon footprints, company carbon footprints, and policy studies, it is important to select a carbon accounting approach that is appropriate for the intended use. This report examines the available forest carbon accounting options and the factors to consider in selecting among them. It finds that the “carbon neutrality” debate involves carbon accounting questions related to system boundaries, the greenhouse gases to include, baselines, attribution, and a number of other factors. Because trees require decades to grow, it is especially important that spatial and temporal boundaries are established correctly in studies of forest carbon. Otherwise, the results of the analysis may not properly reflect the renewability of forest biomass and the removals of CO2 from the atmosphere during forest growth. Also important, especially in policy studies, is addressing market responses to increased demand for forest biomass. Studies that use accounting methods that ignore these forces produce results that understate the benefits of using forest biomass. Much of the current debate about the benefits of forest-derived materials and fuels is not about whether these benefits exist but whether the benefits are delayed (the so-called “carbon debt”). Where the benefits are delayed, the estimated delay is reduced by using accounting methods that reflect market responses. The significance of a delay in delivering greenhouse gas mitigation benefits, however, cannot be assessed by carbon accounting alone.