New research by Utrecht University has shown much less plastic is ending up in the oceans than previously thought but that more is floating on the surface.

Earlier, experts estimated four to 12 million tonnes a year were added to the ocean’s plastic soup every year. However, based on measurements at 20,000 sites across the globe, a figure of 500,000 tonnes is much more likely, the research showed.

Nevertheless, the total amount of plastic floating on the ocean surface is higher than previous studies have shown.

“These calculated the surface plastic at 250,000 tonnes, whereas our measurements put that at two million tonnes, plus a million tonnes at a lower depth,” researcher Mikael Kaandorp told Dutch News.

The influx into the ocean means more plastic is accumulating in rivers, which are relatively easier to clean, he said.

“The good news is that most of the plastic is concentrated in big objects, which are easier to collect than microplastics,” Kaandorp said. “But the bad news is that the influx has been growing by about 4% each year. At this rate plastic pollution will double in the next two decades.”

Biologist and environmental activist Merijn Tinga is “cautiously optimistic” about the news, he told Trouw.

“If the plastic soup is smaller than thought, it is a hopeful sign. But even if it’s a hundred times smaller it is still far too much,” he told the paper. Tinga said the solution is to curb the production of unnecessary plastic which is now endangering ocean flora and fauna.

Kaandorp’s findings are very different compared to, for instance, the World Nature Fund which puts the amount of plastic at 150 million tonnes and an annual addition of 11 million tonnes.

The research will be published by journal Nature Geosciences later on Monday.