Is it still possible to save the ocean from plastic pollution?

In an unprecedented achievement, experts at Kyushu University have presented an easily understandable numerical target in order to tackle marine plastic pollution around the world. 

With ocean current maps that record the flow and fate of plastic litter, the research team quantified the needed prevention of marine ecosystems from future damage: at least a 32% reduction in plastic littering by 2035.

Marine plastic pollution has attained the status of a global problem, and this situation is likely to deteriorate further in the absence of significant interventions.

Monitoring ocean plastic pollution 

For years, Professor Atsuhiko Isobe from Kyushu University’s Research Institute for Applied Mechanics has been monitoring and tracking plastic pollution in the ocean. 

In 2022, the team reported that an estimated 25.3 million metric tons of plastic waste had already entered the oceans, and nearly two-thirds of that amount cannot be tracked.

“My research focuses on tracking where plastic waste goes after being released into water sources such as rivers and oceans. We use computer models to track how plastics move and break down over time,” explained lead author Chisa Higuchi, a postdoctoral fellow in Isobe’s lab.

Microplastics will continue to rise

Plastic waste remains in the environment for extended periods, gradually breaking down into smaller particles. 

While larger plastics can be collected and removed more easily, they eventually degrade into particles smaller than 5 mm, known as microplastics, which are far more challenging to retrieve. 

These microplastics are particularly concerning because they are more likely to be ingested by marine life. Even if plastic littering stopped today, the amount of microplastics in the oceans would continue to rise.

Halting marine plastic pollution 

At the 2019 G20 Osaka Summit, global leaders introduced the Osaka Blue Ocean Vision, with the aim of halting the increase in marine plastic pollution by 2050. This initiative focuses on improving waste management strategies through international collaboration.

“We wanted to figure out what would be the ideal scenario for the Osaka Blue Ocean Vision to succeed. So, we utilized computational modeling along with fieldwork studies to understand where and how plastics flow into the oceans,” Higuchi explained.

Projecting plastic emission routes

The researchers studied how long different types of plastics take to break down and collected data from plastic emission routes, including rivers and other sources that transport waste into the ocean.

“What we came up with are something akin to weather forecast maps, but instead of showing when and where it will rain, these maps show different scenarios on when and where plastics will end up,” Higuchi said.

Their projections suggest that reducing the amount of plastic entering the oceans by 32%, or around 8.1 million tons, by 2035 could lead to more than a 50% reduction in ocean plastic by 2050. 

The impact is even more significant in heavily polluted areas such as the Yellow and East China Seas, where plastic waste could be reduced by up to 63% according to their models.

Stopping new waste from entering oceans

“Not only does this give the Osaka Blue Ocean Vision concrete targets, but it also gives governments and businesses metric goals,” said Higuchi. “Naturally, we need to go beyond cleaning existing pollution; we must cut new plastic waste entering our oceans and rivers.”

According to Isobe, this target is attainable if we use strategies like improving waste management, promoting reusable alternatives to single-use plastics, and enhancing public awareness.

“Many people can be pessimistic when hearing about the ongoing plastic waste problem in our lives. But I remain optimistic that we can find our way out of this predicament,” said Isobe. 

The role of fisheries

The researchers noted that plastic emissions from fisheries, which were not included in this study, are also a major concern for marine pollution. 

The experts emphasized that the 32 % reduction scenario is only based on land-based mismanaged plastics, so different reduction scenarios are needed for fisheries. 

Reducing ocean plastic from rivers

“Among all the concerns, plastic waste management should be prioritized. Reducing the emissions of macroplastic waste from rivers into the ocean is the most important solution that humans can manage,” the researchers concluded. 

“We must note that ocean plastics have inertia, so microplastics will continue to increase even if we suddenly stop increasing land-based plastic emissions because of the legacy plastics accumulated on land.”

The study is published in the journal Marine Pollution Bulletin.

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