A new study involving scientists from around the world suggests there are more than 79,000 tonnes of ocean plastic in a 1.6 million square kilometre area of the North Pacific Ocean, often referred to as the Great Pacific Garbage Patch. That's 16 times more than previous estimates.

The Ocean Cleanup Foundation commissioned the expedition in 2015 to examine the eastern part of the patch. Using 30 vessels and a C-130 Hercules airplane, they catalogued a sample of more than one million pieces of plastic, mostly made up of microplastics that measure less than 0.5 centimetres in diameter.

The study suggests the total amount of microplastics in the Great Pacific Garbage Patch totals more 1.8 trillion pieces, a number that far exceeds earlier estimates.

Around the world, ocean currents form circular areas called gyres, the centre of which are calm. It's here where garbage can get trapped, as in the North Pacific Ocean. Large pieces can break down into smaller pieces, which can be ingested by marine life.

Plastic samples collected during The Ocean Cleanup’s Mega Expedition in 2015. (The Ocean Cleanup Foundation)

Scientists found plastic bottles, containers, packaging straps, lids, ropes and fishing nets among the debris that had been accumulating for decades. One of the identifiable objects was dated 1977. Seven were from the 1980s and 17 from the 1990s.

Plastic from Japan, believed to be debris from the 2011 tsunami, was also found in abundance.

Laurent Lebreton, lead author of the paper published in Scientific Reports told CBC News that it's estimated that 10 to 20 per cent of the plastic in the region is from that single event.

Plastic in the oceans is particularly concerning, as marine life can consume and potentially die from it.

But larger objects, such as fishing nets are equally concerning, said Laurent Lebreton, lead author of the paper.

"People have been focusing on microplastics, because it's likely to be the one to have the most adverse effects on marine life, because of ingestion," Lebreton said. "But we need to understand the full-size picture of plastics, starting from the tiniest piece to larger debris."

Large debris stored on the deck of the Mega Expedition mothership. (The Ocean Cleanup Foundation)

Over time, the larger debris can degrade and form smaller plastics that are harder to clean up, an objective of the Ocean Project Foundation.

Plastic 'smog'

Lebreton was surprised by how much large debris was seen, such as marker buoys that have floated away from their intended locations.

"When you go out into the middle of the ocean, you find that there's a lot more fishing gear than was expected," he said.

"A lot of focus has been pushed toward land-based sources of plastic and waste and single-use plastic, and that's fair, but it's also good to remind us that that's not the only source, that fishing and aquaculture and marine-based sources also contribute to the problem."

The Great Pacific Garbage Patch by the numbers. (The Ocean Cleanup Foundation)

Marcus Eriksen, founder and research director of the 5 Gyres Institute, which aims to reduce global plastic pollution, said that there is nowhere plastic isn't found.

"It's more akin to a smog of microplastics," he said. "With 5.25 trillion particles of plastics and 92 per cent of microplastics, smaller than a grain of rice … it's pretty much everywhere as smog."

Cleanup efforts

And while Eriksen supports initiatives like The Ocean Cleanup Foundation, which plans to use nets to collect ocean plastic, he says that's not a solution by itself.

"I applaud them for going after the big stuff in the middle of the ocean. That's great," he said. "We need to keep those nets from shredding into microplastics. But it's disingenuous to say you're cleaning the oceans when you're doing nothing to stop the flow of trash at land and sea."

Mega Expedition mothership R/V Ocean Starr fully deployed above the Great Pacific Garbage Patch. (The Ocean Cleanup)

Eriksen said that what's needed is a wide-scale effort beginning at the source.

"Policy has to have [manufacturers] clean up their act," he said. "And make smarter products and think of the full life cycle; stop making something that, when it becomes waste, becomes a nightmare for everyone."

Both Lebreton and Eriksen would like to see less single-use plastic as well as a focus on cleaning up beaches and shores, before it makes its ways into our oceans.

"We've created a monster with plastic," Lebreton said. "This [study] shows the urgency of the situation and shows that we need to act quickly."