Concentrations of microplastics in the ocean have increased over the past 18 years, with researchers now estimating that there are 2.3 million tons floating in the oceans worldwide.
Microplastics – defined as plastic particles less than 5 millimeters in length – is common found in the bodies of turtles, whales and fish. Studies have been tracking microplastic pollution in the oceans since the 1970s, but it wasn’t until 2005 that plastic concentrations began to rapidly and steadily increase.
Marcus Eriksen and Lisa Erdle at the 5 Gyres Institute in Santa Monica, California, and their colleagues looked at data on surface ocean plastic pollution collected between 1979 and 2019. That data came from more than 11,000 collection stations covering most of the major oceanic regions.
The patch data made it impossible to identify any clear trends in plastic concentrations between 1979 and 1990, while between 1990 and 2004 plastic concentrations showed fluctuations with no clear trend.
But the team found that over the past 18 years, ocean plastic concentrations have increased dramatically, to more than 10 times their 2005 levels.
“We found an alarming trend of exponential growth of microplastics in the global ocean since the millennium, amounting to more than 170 trillion plastic particles,” Eriksen said in a press release.
The sharp increase in concentrations since 2005 may be due to a boom in plastic production during this period, Erdle said. Global plastic production nearly doubled between 2005 and 2019, from 263 million tons to 460 million tons, according to the OECD and Our World in Data.
It could also be the result of a failure to introduce mandatory measures to reduce pollution, Erdle said, even as waste accumulates as new plastics enter the oceans and older pieces break down into microplastics. . “In recent years, no international rules have existed, and we are seeing a rapid increase in plastic pollution in the world’s oceans,” he said.
The study, which Erdle says is unique in its geographical scope and four-decade time span, only looked at data up to 2019. This is in part because the researchers needed to set a “clear cut-off point” for analysis, says Erdle.
Since then, several countries, including the UK, have introduced laws to tackle microplastic pollution, such as banning the use of plastic straws and reducing demand for single-use carrier bags.
But Erdle believes that more radical action targeting the entire global plastic industry is needed to make a real reduction in marine pollution levels.
In 2022, countries agreed to form a global agreement to tackle plastic pollutionwith a draft text expected by 2024. Erdle said the agreement must be binding and enforceable, and address the entire life cycle of plastics.
The agreement should include a limit on overall plastic production, he said, describing the proposal as an “effective tool” to reduce microplastic concentrations in the ocean.
Without sweeping changes in plastic policy, the rate of plastic flowing into the world’s oceans could be 2.6 times higher by 2040 compared to 2016, the study warns.
Other scientists have too supported calls for global limits on plastic productionbut such a move would be very controversial and it is likely to be a heavy battle of petrochemical industries.