Coastal populations put about 8m tonnes of plastic rubbish into the oceans in 2010, an annual figure that could double over the next decade without major improvements in waste management efforts, scientists warn.
The mountain of plastic litter, including bags, food packaging and toys, was equivalent to five full shopping bags of debris for every foot of coastline bordering nearly 200 countries the team studied.
Though researchers have known about plastic waste in the oceans for 40 years, the latest report, published in the journal Science, is the first to attempt a detailed estimate of how much plastic made on the planet finds its way into the oceans.
The figures suggest that about 10 to 30 times more plastic debris ends up in the oceans than surveys have found floating about on the surface. In one recent survey, an international team reported more than 5 trillion pieces of plastic are floating in the world’s oceans, collectively weighing nearly 269,000 tonnes.
In the latest study, researchers at the University of Georgia and the Sea Education Association in Massachusetts calculated the amount of waste plastic generated in 192 countries with coastlines on the Atlantic, Pacific and Indian Oceans, and the Mediterranean and Black seas. From data on regional manufacturing and waste management practices, they worked out that 4.8m to 12.7m tonnes of plastic rubbish wound up as ocean debris in 2010.
“This input of plastic waste to the oceans is several orders of magnitude more than we can see, which means there’s a lot of plastic out there that we are not finding,” said Jenna Jambeck, the first author of the study at the University of Georgia.
Some countries still dump plastic litter into watercourses that carry the material out to sea. But much of the plastic made on land becomes marine debris because it is not properly disposed of in landfills or at recycling plants. Left in piles in coastal areas, the waste can easily blow into waterways or be carried out to sea by flood water.
Once plastic reaches the oceans it forms floating waste, washes up on coastlines, and accumulates on sea floors. Larger items like bags, wrapping and fishing gear can entangle dolphins, turtles and even whales. Small pieces are eaten by fish, turtles and seabirds. Over time, the material weathers down into tiny particles that can be ingested even by small marine animals. The pollution is extremely difficult to remove from the environment or trace back to its source.
In the study, Jambeck and her colleagues ranked the 20 countries responsible for the most waste plastic ending up in the oceans. The greatest sources were not only the major plastic producers, but generally those nations with the worst waste management practices.
China topped the table with 1.32 to 3.53m tonnes of plastic reaching the oceans in 2010. Indonesia followed, where 83% of waste was mismanaged, added 0.48 to 1.29m tonnes of marine plastic to the seas that year. The US ranked 20th, where only 2% of waste was badly handled, and 0.04 to 0.11m tonnes of plastic found its way to the ocean. Sixteen of the top 20 polluters are middle income countries where fast economic growth is not accompanied by major improvements in waste handling.
A man walks beside the scattered plastic trash brought in by strong waves at Kuta Beach on January 17, 2014 in Kuta, Indonesia. The sight of trash washed up on Kuta beach has become an annual phenomenon as piles of debris are carried to the beach by strong currents during the winter months. Kuta Beach is one of Bali’s top tourist destinations, however during the winter months waste materials are swept up onto the beaches in Java, Bali, and Nusa Tenggara. Facebook Twitter Pinterest
Kuta beach, Indonesia, strewn with plastic litter. Up to 83% of waste is mismanaged in the country. Photograph: Agung Parameswara/Getty Images
According to the report, the cumulative amount of plastic in the seas will soar tenfold by 2025 if nothing is done to slash waste generation or manage it more effectively. The current annual rate of 8m tonnes put into the oceans could also double by 2025 without action.
If changes are made, they could have a huge impact, the scientists claim. Reducing mismanaged plastic waste by 50% in the top 20 ranked countries would cut the pile of plastic likely to end up in the oceans by 41% in 2025. More stringent caps on plastic in waste streams, and better disposal in the top ten-ranked countries could reduce the amount of new marine plastic to 2.4 to 6.4m tonnes annually by 2025.
Though the greatest gains would come from better waste processing in regions where waste management is the poorest, Jambeck stressed that substantial improvements were possible even in countries with effective waste disposal. “It’s not just about improving the infrastructure in other countries.” she said. “There are things we can do in our daily lives to reduce the amount of waste plastic we all produce.”
In December, a team led by Lucy Woodall at the Natural History Museum in London, found “microplastic” debris had accumulated in deep sea sediments, with some as deep as 3000m.
“Marine litter appears to be a much more serious phenomenon than previously thought with studies from the last six months suggesting this pollutant is all pervasive in our oceans and is present in much larger quantities than previously thought,” Woodall said.
Microplastic deposits found deep in world’s oceans and seas
“The world’s oceans cover such a large surface area and by nature are remote from much of human habitation, therefore it is unsurprising that every new study adds to our understanding how serious this issue is. This environmental challenge is one entirely of human making, but we can all help by starting to value, reduce, recycle and reuse plastic products.”