Despite recent private efforts, the global problem of plastic pollution won’t be solved by clean-up devices that collect waste from the ocean surface, according to a new study. The authors call for collection at rivers or a combination of river barriers and clean up devices as an alternative solution.

Plastic waste has become a global and widespread problem. Marine plastic debris is now found in coastal areas all around the globe. Its accumulation in the environment is increasingly hazardous and global policy actions have been invoked to reduce the effects of plastic pollution.

A group of international researchers compared estimates of current and future plastic waste with the ability of floating clean-up devices to collect it. They found the impact of such devices was “very modest” and that river barriers could be more effective, reducing pollution “significantly” when used alongside surface clean-up technology.

“The important message of this paper is that we can’t keep polluting the oceans and hoping that technology will tidy up the mess,” said Dr. Jesse F. Abrams, co-author in a press release. “Even if we could collect all the plastic in the ocean, which we can’t, it’s really difficult to recycle, especially if plastic fragments have floated for a long time.”

The study focused on floating plastic as it’s much easier to remove than sunken waste (depending on size and location). The authors estimated that the amount of plastic that reaches the ocean will peak in 2029, while surface plastic will reach 860,000 metric tons by 2052, more than double the current estimate.

Private initiatives are proposing to collect plastic from oceans and rivers, such as the Ocean Cleanup, which aims to clean the garbage patch in the Pacific using 600 million floating barriers to collect plastic. The study looked at the impact of using 200 of such devices, working non-stop for 130 years until 2150.

Using such devices would reduce global floating plastic debris by 44,900 metric tons. This is just over 5% of the estimated global total by the end of that period, leaving a “very modest” impact “compared to the amount of plastic that constantly enters the ocean,” said Dr. Sönke Hohn, co-author, in a press release.

The best strategy to mitigate marine plastic pollution would be to use river barriers instead, the researchers argued, as most plastic enters the oceans via rivers. This could prevent most of the pollution expected for the next decades. Nevertheless, the barriers couldn’t be installed on a large scale as large rivers are important for global shipping.

The researchers also suggested other paths to tackle the plastic problem across the world, including implementing extended producer responsibility strategies, creating taxes, fees, and/or bans on single-use plastic, promoting a circular economy and increasing recycling rates, among others.

“Plastic is an extremely versatile material with a wide range of consumer and industrial applications, but we need to look for more sustainable alternatives and rethink the way we produce, consume and dispose of plastic,” said Professor Agostino Merico, of Leibniz Centre for Tropical Marine Research and Jacobs University, co-author of the study.

The study was published in the journal Science of the Total Environment.