An Australian study says there is more plastic than plankton in some parts of the Pacific Ocean and it will remain that way for hundreds, possibly thousands of years.
A team of climate researchers from the Australian Research Council has been investigating the formation of masses of plastic in the world's oceans, the largest being in the eastern Pacific.
The team leader, Erik Van Sebille, says the plastic stretches thousands of kilometres across the region and is often too small for the naked eye to see.
Mr Van Sebille says that it could take 500 years to stop the growth of these masses.
"We already put so much plastic in the ocean that even if we would stop tomorrow, if everybody would join forces and say 'no more plastic as of today' these patches would still grow. There is so much plastic floating around in all of the other oceans that it still keeps on accumulating."
Erik Van Sebille says one way to improve things would be to increase the availability of biodegradable plastics.