Amount of plastic in the ocean is less than previously thought – 08/12/2023 – Environment

There is less plastic pollution going from land to ocean than scientists previously thought, according to a study published Monday in the journal Nature Geoscience.

Researchers estimated that around 500,000 tons of plastic end up in the ocean each year, half of which comes from land. The other half comes from the fishing industry, in the form of nets, ropes, buoys and other equipment.

A previous study, published in 2015 and widely publicized, estimated that around 8 million tons of plastic would be entering the ocean each year from rivers alone.

The new research may seem like good news, but the picture is nonetheless complicated: according to the most recent study, the amount of plastic in the sea is increasing by about 4% per year.

Even a small annual increase adds up to a huge accumulation over time. The authors concluded that within 20 years the amount of plastic present on the surface of the sea could double.

“We are accumulating more and more plastic in the environment,” said Mikael Kaandorp, lead author of the study and a postdoctoral researcher at the research institute Forschungszentrum Jülich in Jülich, Germany.

Plastic pollution harms marine fauna and flora and humans

Marine animals can become entangled in discarded fishing nets, ropes and packaging. Many also get sick or injured from ingesting plastic. Some animals die of starvation because their digestive system is clogged with plastic.

Very small pieces of plastic, called microplastics, can easily move up the food chain from fish and other seafood to humans. Sometimes these microplastics have already absorbed toxic chemicals or become coated with them.

On land, plastic that does not enter the sea still pollutes rivers, lakes, beaches and land.

Background

The 2015 study was one of the first comprehensive research efforts to account for how much plastic ends up in the ocean. But there was a big discrepancy between his estimate of 8 million tons and the amount of plastic observed in the ocean. More recent studies have tried to address this disparity.

The paper published on Monday combined data from many previous studies that sampled small plastics in the ocean using trawl nets or that observed larger plastics from ships or from the shore. The researchers fed this data into a computer model of how objects move through the ocean to estimate how much plastic is entering the ocean each year and how much total plastic pollution is floating on the sea surface.

Most of the total plastic pollution in the ocean is floating plastic, and this is the most problematic for marine animals because floating plastic can easily be ingested.

The new study estimated that in 2020, approximately 3.2 million metric tons of plastic waste was floating on the sea surface and suggested that this marine pollution remains on the surface longer than previously thought.

What comes next

Once it’s in the ocean, it’s difficult to remove plastic pollution. Trying to do so would be both a logistical and an ecological challenge: there is no way to collect plastic without also collecting and harming marine fauna in the process. And humans are throwing more plastic into the sea all the time.

Kaandorp said his study’s estimates of this continued buildup highlighted the importance of stopping the flow. “The study shows that we really need to take action,” he said. “It’s going to take a really long time for these plastics to be removed from our seas.”

This year, countries agreed to start writing a global treaty to reduce plastic pollution.

“The policy is not keeping pace with the speed at which the problem is getting worse,” said Marcus Eriksen, co-founder of the nonprofit 5 Gyres, which works to reduce plastic pollution.

Eriksen published a study in March that estimated similar amounts of plastic floating in the sea and concluded that this type of pollution has been growing rapidly since 2005.

“The UN treaty can change that,” he said, if it regulates what types of plastic products can be made, makes manufacturers more responsible for recycling and is legally binding.

_{Translated by Clara Allain}