Stopping new plastic from entering the oceans is essential but will not be enough to prevent the continued accumulation of microplastics, according to a new study by researchers from Ritsumeikan University and international partners.

The research shows that reducing plastic at its source must be combined with timely cleanup of existing marine debris, particularly larger plastic waste that can gradually fragment into smaller particles.

The study, published in Communications Earth & Environment on September 12, 2026, used a system dynamics model to assess how different combinations of plastic source reduction and cleanup strategies could affect marine plastic pollution through 2050.

Researchers examined the transport, degradation and removal of initially buoyant macroplastics across shorelines, coastal waters and offshore areas, as well as their eventual breakdown into microplastics.

The research team included Professor Takuro Uehara of Ritsumeikan University, Dr. Mateo Cordier of Université de Versailles-Saint-Quentin-en-Yvelines—Université Paris-Saclay in France, and Laurent Lebreton of The Ocean Cleanup in the Netherlands.

“The framework is designed to look at marine plastic pollution as a dynamic problem rather than a one-time cleanup challenge.” Says Prof. Uehara. “By linking plastic inputs, the movement and breakdown of debris, cleanup timing and location, and the associated costs, it allows to explore which combinations of prevention and cleanup could be both environmentally effective and economically realistic. This provides a basis for more informed decisions about where and when cleanup efforts should be prioritized.”

The researchers tested seven scenarios combining different levels of plastic source reduction with varying cleanup strategies.

In scenarios targeting the elimination of new marine plastic inputs, pollution entering the ocean was progressively reduced from 2026 until reaching zero by 2050.

The researchers then compared delayed, constant and accelerated cleanup strategies to determine how timing and intensity would affect the amount of plastic remaining in the ocean.

The modelling found that halting plastic inputs by 2050 could reduce the cumulative amount of plastic entering the ocean between 1950 and 2050 by 51.4% compared with a business-as-usual scenario.

However, source reduction alone would not eliminate the existing stock of marine plastic.

Without cleanup, microplastics were projected to account for 58.4% of accumulated marine plastic by 2050.

The study also found that cleanup without reducing new plastic inputs would be insufficient to address the scale of the problem.

For example, delayed cleanup under the business-as-usual scenario was projected to leave approximately 10,319 kilotonnes (kt) of microplastics in the ocean by 2050, compared with about 10,146 kt when source reduction was combined with delayed cleanup.

The researchers found that the timing of cleanup was critical.

All of the cleanup strategies examined focused on removing macroplastics rather than microplastics, which remain difficult and costly to recover at2050.

Under a source-reduction scenario with delayed cleanup, approximately 10,168 kt of plastic remained in the ocean.

That figure fell to 8,824 kt with constant cleanup and to 7,312 kt when large scale.

Among scenarios combining source reduction with comprehensive cleanup, accelerated action produced the lowest amount of remaining plastic by 2050.

Under a source-reduction scenario with delayed cleanup, approximately 10,168 kt of plastic remained in the ocean.

That figure fell to 8,824 kt with constant cleanup and to 7,312 kt when cleanup was accelerated.

The findings suggest that removing larger plastic debris before it breaks down into microplastics can significantly reduce future accumulation. Early intervention is particularly important because existing large-scale technologies are not effective at recovering microplastics once they are widely dispersed.

However, the researchers also highlighted the substantial financial costs associated with faster cleanup.

Delayed full cleanup was estimated to cost an average of €1 billion annually, while accelerating cleanup between 2026 and 2050 could raise annual costs to around €3.4 billion.

Offshore cleanup operations are more expensive than efforts carried out closer to shore. Costs can also rise over time as cleanup operations remove the most accessible concentrations of plastic, leaving smaller and more dispersed quantities that are increasingly expensive to recover.

The study’s findings have implications for international efforts such as the Osaka Blue Ocean Vision, which seeks to halt additional marine plastic pollution by 2050 and was endorsed alongside the G20 Implementation Framework for Actions on Marine Plastic Litter.

The researchers stressed that preventing plastic from entering the environment remains the most important long-term measure.

Upstream action could include reducing plastic production and consumption, improving waste collection and strengthening recycling infrastructure.

Industries also have a role to play by reconsidering production practices and identifying more sustainable levels of plastic manufacturing.

The study suggests that relying primarily on large-scale cleanup operations would place significant financial and technological burdens on governments and other organisations.

Prof. Uehara said, "The scale of marine pollution demands more than just better cleanup strategies. Relying on massive recovery efforts to balance out unchecked plastic waste is a structurally unsustainable solution."

Overall, the research concludes that source reduction and cleanup should be pursued together rather than treated as alternatives.

Eliminating new plastic inputs by 2050 could substantially reduce future pollution, but existing marine debris will continue to fragment unless it is removed.

Accelerating targeted cleanup while macroplastics remain recoverable can therefore limit the formation of additional microplastics, although significant accumulation is expected to remain.

The study highlights the need for policymakers to balance environmental effectiveness, cleanup timing and financial costs while prioritising measures that prevent plastic waste from reaching marine environments in the first place. -TradeArabia News Service