HONG KONG: The report, which appeared in the journal Science, is the most ambitious effort yet to estimate how much plastic debris ends up in the sea.
Jenna Jambeck, an assistant professor of environmental engineering at the University of Georgia and lead author of the study, said the amount of plastic that entered the oceans in the year measured, 2010, might be as little as 4.8 million metric tons or as much as 12.7 million.
The paper’s middle figure of eight million, she said, is the equivalent of “five plastic grocery bags filled with plastic for every foot of coastline in the world” — a visualization that, she said, “sort of blew my mind.”
By 2025, she said, the amount of plastic projected to be entering the oceans would constitute the equivalent of 10 bags per foot of coastline.
The researchers, from the United States and Australia, derived their estimates through a complex calculation that began with the overall mass of waste produced per person annually in 192 nations that have coastlines, worked through the proportion of that waste likely to be plastic, and how much of the plastic could end up in the ocean because of each nation’s waste management practices. The researchers then projected the amount of waste going forward based on population growth estimates.
“This is a significant study,” said Nancy Wallace, director of the marine debris program at the National Oceanic and Atmospheric Administration, who saw the paper before it was published.
Ms. Wallace applauded what she considered the sophisticated use of available data to estimate the amount of plastic entering the marine environment, both collectively and country by country. “Of course we know these aren’t absolute numbers, but it gives us an idea of the magnitude, and where we might need to focus our efforts to affect the issue,” she said.
The research also lists the world’s 20 worst plastic polluters, from China to the United States, based on such factors as size of coastal population and national plastic production.
According to the estimate, China tops the list, producing as much as 3.5 million metric tons of marine debris each year. The United States, which generates as much as 110,000 metric tons of marine debris a year, came in at No. 20.
