Researchers at The Ocean Cleanup and Wageningen University built a high-resolution global model of how plastic waste moves from land through rivers into the sea, calibrated with field measurements.
They estimated that rivers carry 0.8–2.7 million tonnes of plastic to the ocean each year, and that more than 1,000 rivers account for 80% of that total. Small and medium rivers flowing through coastal cities, especially in Southeast Asia, contribute far more than their size suggests.
This matters for where to act: rather than focusing on a few giant rivers, the study points to thousands of local interventions in coastal cities.
The earlier claim that '10 rivers carry 90% of ocean plastic' came from the same group's 2017 modelling and has been superseded by this paper. It should no longer be used.