Blame It on the Rivers that Feed the Sea.

• Position: PLASTIC POLLUTION

With the help of new measurements and modeling, a study by Ocean Cleanup--a nonprofit developing advanced technologies to rid the world's oceans of plastic--shows that 1,000 rivers shed almost 80% of plastic emissions.

These findings indicate that ocean plastic pollution is caused by a greater number of small and medium-sized rivers, defined by a set of geographic factors that determine the highest contribution to the inflow of plastic into our oceans. This understanding is contrary to previous estimations that a small number of massive rivers are the major contributors.

On the one hand, the 1,000 number represents one percent of all rivers globally, yet, on the other hand, this estimation is about 100 times as many rivers as was thought to represent the majority of emissions, based on previous studies published in 2017.

"While the plastic problem may seem daunting in scale, this updated understanding of where plastic becomes ocean plastic will allow for a much more targeted intervention," says Boyan Slat, founder and CEO of The Ocean Cleanup. "As we see huge differences in pollution levels across the globe, these results could help to rapidly increase the speed of solving the problem. We will use this new data as a guide for our cleanup activities, and we hope others will, too."

The plastic waste that flows into the oceans not only is determined by the amount of plastic generated in a...