A new study estimates that 4 million to 12 million metric tons of plastics are washed into the world's oceans annually — or between 1.5 and 4.5 percent of the world's total plastic production.
The number comes from a study on marine debris from the National Center for Ecological Analysis and Synthesis (NCEAS) at the University of California, Santa Barbara, which was published Feb. 12 in Science magazine.
"For the first time, we're estimating the amount of plastic that enters the oceans in a given year," said study co-author Kara Lavender Law, a research professor at the Massachusetts-based Sea Education Association. "Nobody has had a good sense of the size of that problem until now," she said in a news release.
According to the authors, this is the first estimate of plastic marine debris since 1975, when the National Academy of Sciences estimated that 0.1 percent of global plastic production swept out to sea annually.
Researchers looked at how much plastics waste every coastal country in the world produces, and they estimated that between 15-40 percent of that total ends up in the ocean.
Some of the 192 countries included in the model have no formal waste management systems, said Jenna Jambeck, a professor of environmental engineering at the University of Georgia, and lead author of the study. Solid waste management lags behind clean water and sewage treatment as priorities for urban environmental engineering infrastructure, she said.
The authors predict the annual amount of plastic marine debris will more than double in the next 10 years.
According to the Science article, China generates the most plastic marine debris, estimated at as much as 3.5 million tons annually. The United States was No. 20, at as much as 110,000 metric tons per year. The estimates were based on 2010 data.
Patty Long, the Society of the Plastics Industry Inc.'s senior vice president for industry affairs said SPI has been aware of the report since last year and that it has a 30-year history of working with the National Oceanic and Atmospheric Administration in the U.S. and the nonprofit group Ocean Conservancy.
"We're as concerned about this as they are," Long said.
SPI and other industry groups have been focused on recycling efforts and preventing plastic trash from reaching the oceans in the first place, especially since efforts to remove plastics from the sea are largely ineffective, as the report points out.
"We think expanded access to recycling is the way to keep plastic out of the oceans," Long said. “Litter is a behavioral issue," she said, and behaviors much change around the world to keep the oceans plastic-free.
The American Chemistry Council reacted to the study by calling for global cooperation, including within the plastics industry, to reduce the amount of plastics marine debris.
“Scientists are working to answer many questions about marine debris, but one thing is certain: The most important thing we can do right now is to keep all trash, including plastics, from getting into our oceans in the first place,” said Steve Russell, vice president of ACC's plastics division, in a news release.
“The global dimensions of marine debris are creating opportunities for world leaders, [nongovernmental organizations] and the private sector to work together, and America's plastics makers will continue to partner with these and other stakeholders to develop solutions for a cleaner ocean.
“Used plastics should be treated as valuable resources and recycled whenever possible or recovered for their energy value when recycling is not feasible.”