Buoyant plastic pollution could remain at the ocean surface for more than 100 years, even if all plastic inputs were halted today, according to a new study co-led by scientists at HR Wallingford and Queen Mary University of London.

The research presents a model that simulates how large plastic debris breaks down and interacts with 'marine snow', organic particles that help transport material to the deep sea. The findings offer critical insights into the long-term fate of microplastics and the challenges of removing plastic from marine environments.

Professor Andrew Manning, technical director at HR Wallingford and associate professor at the University of Plymouth, said: “This study helps explain why so much of the plastic we expect to find at the ocean surface is missing. As large plastics fragment, they become small enough to attach to marine snow and sink. But that transformation takes decades. Even after a hundred years, fragments are still floating and breaking down. To tackle the problem properly, we need long-term thinking that goes beyond just cleaning the surface.”

The model shows that degradation is the limiting factor in removing plastic from the ocean surface. Even after a century, around 10% of the original plastic may still remain afloat, continuing to release microplastics.

Image courtesy Sea Shepherd

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