Some eight million metric tons of plastic waste makes its way into the world’s oceans each year, and the amount of the debris is likely to increase greatly over the next decade unless nations take strong measures to dispose of their trash responsibly, new research suggests.

The report, which appeared in the journal Science on Thursday, 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.”