Towards circular plastics within planetary boundaries

Abstract The rapid growth of plastics production exacerbated the triple planetary crisis of habitat loss, waste pollution, and greenhouse gas (GHG) emissions. Circular strategies have been proposed for plastics to achieve net-zero GHG emissions. However, the implications of such circular strategies on absolute sustainability at planetary scale have not been examined. This study links a bottom-up model for the life cycle of 90% of global plastics to the planetary boundary framework. Here, we show that a climate-optimal plastics industry combining current recycling technologies with biomass and CO2 transgresses sustainability thresholds by up to four times. However, improving chemical recycling would open a safe operating space for sustainable plastics in 2030, provided that recycling rates reach at least 75%. The analysis also shows that sustainable plastics require not only novel technologies but also a fundamental change in our perception of plastics as cheap and disposable products.