Bioenergy with carbon capture and storage (BECCS) is a key component of pathways to net zero, yet potential interactions with forest carbon dynamics, cascading wood strategies, and progressive decarbonisation and CCS deployment are poorly represented in assessments. Here, using dynamic life cycle assessment, we explore these factors for sawmill residue-derived BECCS value chains over long, yet flexible, time-horizons. BECCS improves the climate performance of bioenergy and consistently delivers long-term global cooling, even in a fully decarbonised economy where substitution benefits cease, provided forest carbon stocks are maintained. Cascading wood use delivers greater near-term cooling via product substitutions compared to direct diversion to bioenergy, and provides temporary carbon storage complementing later deployment of permanent carbon storage via BECCS. Without cascading use, unharvested forests can deliver stronger near-term cooling than direct diversion to bioenergy, even with full BECCS deployment. However, the sink strength diminishes as forests mature, and sequestered carbon may be vulnerable to disturbances such as wildfire. Crossover points highlight the critical role of cascading wood use coupled with BECCS to ensure continuous and enduring cooling effects. Transferring biogenic carbon from forests to geological stores, via multiple uses, is likely to enhance the longevity and resilience of carbon dioxide removal in a rapidly warming world.