An option space approach to wood use: Providing structural timber for buildings while safeguarding forest integrity.

Wood use is crucial for climate-change mitigation, but strategies range from increasing harvest to conserving forests. To reconcile contradictions, we conceptualize an option space that considers both social and ecological thresholds. We couple the material flow model RECC and the forest model CRAFT to quantify the option space for wood use in the global building sector and current forest areas from 2020 to 2050. We juxtapose four demand scenarios with four supply scenarios that meet material and ecosystem service thresholds, respectively. In 12 of the 16 resulting scenario combinations, supply exceeds demand. They differ in regional self-sufficiency (6-9 out of ten world regions), average primary wood availability beyond structural timber use (0.2-1.4 GtCyr-1), and overall climate impacts (2.0-8.0 GtCO2eqyr-1). Substantially increasing wood intensity in buildings within ecological limits is only feasible in a low floorspace scenario with increasing circularity, emphasizing the need for nuance in claims regarding the sustainability of wood use.