A local-to-global emissions inventory of macroplastic pollution

<title>Abstract</title> Negotiations for a Global Treaty on plastic pollution¹ will shape policy on plastics production, use, and waste management for the coming decades. Parties will require a detailed baseline of waste flows and plastic emission sources at high resolution to enable identification of pollution hotspots and their causes². Nationally aggregated waste management data can be distributed to smaller scale to identify generalised points of plastic accumulation and source phenomena^3-11. However, it is challenging to use this type of spatial allocation to assess the conditions under which emissions take place^12,13. To this, we developed a novel methodology for a global macroplastic waste inventory; creating an explanatory framework that combines conceptual modelling of emission mechanisms with measurable activity data. Using machine learning and probabilistic material flow analysis we identify hotspots worldwide (50,072 municipalities) from five land-based plastic waste emission sources. We estimate global plastic waste emissions at 52.5 million metric tonnes (Mt), of which 57% wt. are open burned. Highest contributions: India (9.7 Mt), Nigeria (3.5 Mt), and Indonesia (3.0 Mt). Uncollected waste is the dominant emissions source across Global South. This detailed evidence baseline can inform Treaty negotiations and help develop national and sub-national waste management action plans and source inventories.