How do afforestation and BECCS differ in their impacts on the land carbon cycle and surface climate?

Abstract Carbon dioxide removal (CDR) plays an essential role in achieving the Paris Agreement targets. Bioenergy with carbon capture and storage (BECCS) and Afforestation and reforestation (AR) are two widely-assumed CDR methods in future mitigation pathways. Here, we compare their CDR potentials and impacts on the land carbon cycle and surface climate by using IPSL-CM6A-LR Earth System Model simulations under the SSP5-3.4-OS temperature overshoot pathway. BECCS removes more carbon from the atmosphere than AR on a global scale. But an additional CO2 release due to land-use change can regionally overcompensate the CDR advantages of BECCS over AR, depending on the carbon capture and storage efficiency of bioenergy crops and the timescales required to achieve the mitigation targets. Besides, the CDR potential advantages are compromised by regionally contrasting impacts on the climate and carbon cycle. The decision to allocate land for bioenergy crops or forests should account for their respective CDR potentials, as well as the effects from their associated biogeochemical and biogeophysical feedbacks.