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Rapid growth in plastic consumption is placing increasing pressure on global waste management systems and contributing to growing carbon footprints. Bioplastics, either bio-based or biodegradable, offer potential environmental benefits including climate impact mitigation and reduction of residual plastic in the environment. However, these benefits are contingent on their End-of-Life (EoL) destinations: under intended EoL destinations such as industrial composting or anaerobic digestion, biodegradable plastics can deliver favorable outcomes, whereas under unintended EoL destinations such as landfills without gas collection, anaerobic biodegradation generates methane, potentially undermining climate benefits. Previous global assessments have not fully incorporated the degradation behavior of biodegradable plastics under realistic waste management conditions. This study quantified the environmental performance of bioplastics under current global waste management trajectories through carbon flow modeling, integrating region-specific EoL destinations of waste in 215 countries and degradability of biodegradable plastics. Material flow analysis revealed that 57% of packaging plastics could be technically substituted with biodegradable plastics. Under current waste management practices, the majority of these bioplastics would be disposed of in landfills without gas collection. Consequently, life cycle greenhouse gas emissions increased by 18% compared to conventional plastics, despite biogenic carbon sequestration benefits. Residual plastics in landfills, aquatic environments, and soil were reduced by 34%, 26%, and 24%, respectively. Sensitivity analysis demonstrated a fundamental trade-off: higher biodegradability reduces plastic accumulation but increases methane emissions under landfill-dominated conditions. These outcomes are determined not by intrinsic material properties but by EoL destinations of waste. Thus, the findings underscore the need for investment in waste management infrastructure to ensure that bioplastics reach intended EoL destinations where their benefits can be fully realized.
Iwamoto et al. (Wed,) studied this question.