Events & Media

An Ocean of Plastic
A new report co-authored by Bren associate professor Roland Geyer calculates the frightening magnitude of plastic waste going into the world’s oceans

February 12, 2015

(Santa Barbara, Calif.) — Plastic pollution has been entering the world’s oceans for decades, and research has documented its effects on more than 660 marine species, from the smallest zooplankton to the largest whales, including fish destined for the seafood market. But until now, just how much plastic is making its way into the world’s oceans and where it all comes from have been mysteries.

Roland Geyer

A new study co-authored by Bren associate professor Roland Geyer and published today in the journal Science quantifies the amount of plastic waste entering the ocean from land and offers a roadmap for developing ocean-scale solutions to the problem of plastic marine pollution. Read the paper here.

The research was conducted by a scientific working group at UC Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS), which is directed by Bren School professor Frank Davis, with support from the Ocean Conservancy. Lead author Jenna Jambeck, professor of environmental engineering at the University of Georgia, coordinated contributions from experts in oceanography, waste management (Geyer), and plastics materials science.

How much plastic is out there?
The researchers found that the amount of plastic waste entering the oceans from land each year exceeds 4.8 million metric tons and may be as high as 12.7 million metric tons — 10 to 1,000 times more than the reported mass of plastic that is floating in the ocean. A metric ton is equivalent to 1,000 kilograms or 2,205 pounds.

“Using the average density of uncompacted plastic waste, 8 million metric tons — the midpoint estimate — would cover an area thirty-four times the size of Manhattan ankle-deep in plastic waste,” said co-author Roland Geyer, an associate professor at UCSB’s Bren School of Environmental Science & Management. “Eight million metric tons is a vast amount of material by any measure. It is how much plastic was produced worldwide in 1961.”

Looked at another way, says Jambeck, “Eight million metric tons is the equivalent of finding five grocery bags full of plastic on every foot of coastline in the one-hundred-ninety-two countries we examined.”

To determine the amount of plastic going into the ocean, Jambeck began with what Roland Geyer described as “a very grand model of all sources of marine debris.”

Plastic trash litters a beach in Haiti.

Their goal was to develop models for each of the sources of debris entering the ocean: land, sea and others. But after gathering rough estimates, said Geyer, “It fairly quickly emerged that the mismanaged waste and solid waste dispersed was the biggest contributor of all of them.” So they focused on plastic.

“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.”

Large-scale removal of plastic marine debris is not going to be cost-effective, and is quite likely simply unfeasible,” said Geyer. “This means that we need to prevent plastic from entering the oceans in the first place through better waste management, more reuse and recycling, and even product redesign and material substitution.”

Knowing how much plastic is going into the ocean is just one part of the puzzle. Millions of metric tons reach the oceans, yet researchers are finding between 6,350 and 245,000 metric tons floating on the surface – largely in the worlds five ocean gyres, where circulating currents create slowly spinning  garbage patches at sea. But as disturbing as the scale of pollution in the gyres is, this study shows that it represents a mere fraction of the total. That discrepancy is the subject on ongoing research.

“Right now, we’re mainly measuring plastic that floats,” said study co-author Kara Lavender Law, a research professor at the Massachusetts-based Sea Education Association. “But there is a lot of plastic sitting on the bottom of the ocean and on beaches worldwide.”

“Investments in improved waste management practices on land, particularly in fast-growing and developing nations, are critical and will lead to substantial reductions in the amount of plastic waste entering the oceans,” said Geyer. “Further, a reduction in the use of plastics and improved plastics recycling in developed countries would be important complements to the infrastructure improvements needed in developing economies.”

The NCEAS working group estimates that by 2025 the total amount of plastic in the world’s oceans could be as high as 155 million metric tons, but according to World Bank calculations, the planet will not reach global “peak waste” before 2100.

“We’re being overwhelmed by our waste,” Jambeck said.

“The numbers are staggering, but as the group points out, the problem is not insurmountable,” said Frank Davis. “The researchers suggest achievable solutions that could reverse the alarming trend in plastics being dumped into our oceans. These range from adequate disposal of waste to capping plastic waste generation.”


Note to editors: Roland Geyer is available at or (805) 893-7234 and Frank Davis is available at or (805) 893-7529. Downloadable images are available at