Impacts devalue the potential of large-scale terrestrial CO2 removal through biomass plantations
Many integrated assessmentmodels (IAMs) rely on the availability and extensive use of biomass energywith carbon capture and storage (BECCS) to deliver emissions scenarios consistent with limiting climate change to below 2 °Caverage temperature rise. BECCS has the potential to remove carbon dioxide (CO2) from the atmosphere, delivering ‘negative emissions’. The deployment of BECCS at the scale assumed in IAM scenarios is highly uncertain: biomass energy is commonly used but not at such a scale, andCCS technologies have been demonstrated but not commercially established.Herewe present the results of an expert elicitation process that explores the explicit and implicit assumptions underpinning the feasibility of BECCS in IAM scenarios. Our results show that the assumptions are considered realistic regarding technical aspects of CCS but unrealistic regarding the extent of bioenergy deployment, and development of adequate societal support and governance structures for BECCS. The results highlight concerns about the assumedmagnitude of carbon dioxide removal achieved across a full BECCS supply chain, with the greatest uncertainty in bioenergy production. Unrealistically optimistic assumptions regarding the future availability of BECCS in IAM scenarios could lead to the overshoot of critical warming limits and have significant impacts on neartermmitigation options.