Several key constraints were considered in the model to remain within the planetary boundaries. With respect to the impacts on biodiversity and land use, we ensured that biomass use did not exceed 0.5 EJ per year. This amount of biomass was considered to be sustainably available from abandoned farmland and surplus woods in Japan. We conservatively estimated this amount by scaling down the potential availability in Japan as reported in the literature , to account for sustainable sourcing . Regarding the impact on novel entities, because of the reduced future demand and improved waste management in the model, the environmental leakage and microplastic pollution in 2050 should be less than those experienced today; thus, no constraints were set regarding the novel entities. Similarly, no constraints were imposed based on other processes in the planetary boundaries because they were less relevant to the chemicals within the scope of this study, which were ethylene, propylene, butadiene, benzene, toluene, xylenes, and methanol.