We might have been wrong about the plastic waste floating about our oceans, choking fish and spreading the waste-signature of humanity.
This is the conclusion of new research done by a team from the University of Cape Town. “Rapid increase in Asian bottles in the South Atlantic Ocean indicates major debris from ships”, was published in the peer-reviewed Proceedings of the National Academy of Sciences of the United States this week.
It starts straight away by tackling what we take to be the truth: “Most plastic debris floating at sea is thought to come from land-based sources, but there is little direct evidence to support this assumption.”
The researchers say that an estimated 12.7-million tonnes of plastic ends up in our oceans every year. But this figure is only for waste that comes from the land. There is a lot more that comes from elsewhere.
To find where waste really comes from, the researchers took data from Inaccessible Island — a 13 square kilometre extinct volcano in the South Atlantic Ocean, between southern Africa and South America.
The island is covered in steep cliffs and beaches with more boulders and less sand. But it is also covered in plastic waste.
This waste has been recorded since 1984.
In 2018, the researchers found over 7 500 plastic bottles and other containers on the island. In just 72 days of monitoring what washed up on the remote island last year, the team picked up 174 bottles. Each one of the bottles can be traced, because it bears symbols that show where and when it was made.
The oldest container on Inaccessible Island came from 1971. But the majority were polyethylene terephthalate drinking bottles that were made recently — 90% were date stamped as being made in the past two years.
When the researchers first started collecting bottles on the island, two-thirds were found to have come from South America — which meant that they had drifted 3 000km. But, by 2009, the majority of bottles were coming from Asia. By last year, 83% of the new bottles came with stamps saying that they were manufactured in China.
Because it takes so long for items to float across vast distances, the bottles had to be coming from a closer source than Asia.
Given this, the researchers conclude that the evidence “indicates that ships are responsible for most of the bottles floating in the central South Atlantic Ocean”.
There are some 150 000 vessels wandering around the world’s oceans. A third of these — at least 50 000 vessels — are in merchant fleets. Although fishing fleets operate in that part of the South Atlantic, they are predominantly from Taiwan and Japan. And the waste is coming from China and other parts of Asia.
The researchers therefore put the blame for the plastic pollution squarely at the world’s merchant fleet.
These are vessels that, when they pollute, are breaking the law of the seas. They are “in contravention of [the]International Convention for the Prevention of Pollution from Ships regulations”.
Inaccessible Island is a World Heritage Site. It is now also the place that reminds us that plastic pollution follows humans wherever they go.