Between five and 13 million tons of plastic waste wind up in the world's oceans every year, and researchers warn that this amount could increase tenfold in the next decade unless the international community improves its waste management practices. Jenna Jambeck and colleagues combined data on solid waste from 192 different coastal countries with factors such as population density and economic status to reach their conclusions. They estimated the amount of plastic that moved from land to sea in 2010 and identified the major sources of this ocean-bound plastic waste, listing the 20 countries -- from China to the United States -- that delivered the most plastic into the oceans that year. Although many studies have highlighted the presence and location of plastic debris in the world's oceans over the years, the amount of plastic that enters the seas annually has been unknown. Using their new model, Jambeck and the other researchers suggest that the coastal countries they studied generated about 275 million tons of plastic waste in 2010, and that 4.8 to 12.7 million tons of that waste wound up in the world's oceans. A country's population size, along with the quality of its waste management systems, largely determines the amount of its waste that might reach the oceans, according to the researchers. Nations around the world need to reduce waste and adopt better management strategies, such as expanded waste recovery systems, in order to prevent the amount of plastic debris in the world's oceans from increasing by a full order of magnitude by the year 2025, they say.