Economic factors influence net carbon emissions of forest bioenergy expansion

There is considerable concern that consuming forest biomass for energy will increase net carbon emissions from forests, which is defined as carbon debt. Using a market-based economic model, we test the effects of 51 demand pathways for forest bioenergy on future forest carbon stocks to assess the likelihood of incurring a sustained carbon debt lasting for several decades. We show that potential forest carbon debt from bioenergy expansion, measured as a near-term decrease in forest carbon sequestration relative to a baseline, occurs and persists only under a specific set of assumptions about carbon accounting, markets, policies, and future biomass demands. Finally, we evaluate whether forest regulations restricting biomass sourcing could influence the scale of carbon debt and/or reduce the time needed to recover the carbon debt (payback period). We show that under similar demand pathways and in the absence of direct carbon policies, imposing limits to supply is likely to reduce the payback period but does not avoid initial carbon debt.