Plastic pollution in the world’s oceans has reached “unprecedented levels” over the past 15 years, a new study has found, calling for a legally binding international treaty to stop the harmful waste.

Ocean plastic pollution is a persistent problem around the globe — animals may become entangled in larger pieces of plastic like fishing nets, or ingest microplastics that eventually enter the food chain to be consumed by humans.

Research published found that there are an estimated 170 trillion pieces of plastic, mainly microplastics, on the surface of the world’s oceans today, much of it discarded since 2005, France24 reported.

“Plastic pollution in the world’s oceans during the past 15 years has reached unprecedented levels,” said the study, published in open-access journal PLOS One. The amounts were higher than previous estimates, and the study found that the rate of plastic entering the oceans could accelerate several-fold in the coming decades if left unchecked.

Cleanup is futile

To produce this new estimate, a group of scientists analysed records starting in 1979 and added recent data collected on expeditions that trawl the seas with nets to collect plastics.

The plastic counted in nets is then added to a mathematical model to produce a global estimate. The 171 trillion pieces are made up of both recently discarded plastics and older pieces that have broken down, lead author Dr Marcus Eriksen from the 5 Gyres Institute told BBC News.

Eriksen went on to say “Cleanup is futile if we continue to produce plastic at the current rate, and we have heard about recycling for too long while the plastic industry simultaneously rejects any commitments to buy recycled material or design for recyclability. It’s time to address the plastic problem at the source.”

The full peer reviewed journal can be read here.