Ocean 'conveyor belt' brings billions of plastic particles into Arctic waters

An ocean current is acting as a kind of conveyor belt leading billions of bits of plastic to a dead end in the Arctic, according to new research published in the journal Science Advances.

A team of scientists, led by Andres Cozar from the University of Cadiz in Spain, found hundreds of thousands of tiny pieces of plastic per square kilometre in parts of the Barents and Greenland seas.

Past research has found that there are more than five trillion pieces of plastic in the world's oceans. About three per cent (or several billion bits) of it ends up in the Arctic.

For this research, Cozar and his team used 17,000 satellite buoys to track the movement of the plastic floating on the surface of the ocean. They were able to see that plastic is carried to the Arctic along an ocean current known as thermohaline circulation, which Cozar refers to as a 'conveyor belt.'

The plastic comes from as far away as the eastern coast of North America and the northwestern coast of Europe.

Once the plastic gets to the Arctic, it eventually sinks.

Cozar said the combination of the ice sheets and the land masses work as a barrier, preventing the plastic from floating any further.

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"The seafloor is the final destination of the floating plastic … it's the great reservoir of plastic debris," said Cozar.

This is leading to what Cozar calls an "accumulation zone" of plastic — similar to the infamous accumulation zone in the Pacific, sometimes called the 'garbage island'.

Cozar said it would take a few decades for the plastic in the Arctic to form an accumulation zone like the one in the Pacific.

No boundaries in the water

Low populations in the Arctic means that the plastic debris is not local.

"The present data demonstrate that high concentrations of plastic debris extend up to remote Arctic waters, emphasizing the global scale of marine plastic pollution and the role that global oceanic circulation patterns play in the redistribution of these persistent pollutants," wrote Cozar, the lead author of the paper.

Rachel Obbard, assistant research professor at the Thayer School of Engineering at the University of Dartmouth in Hanover, N.H., found plastics in Arctic ice cores in 2009.

She said that as the oceans warm and the sea ice decreases, these plastic particles will likely get dispersed further and further. Warmer oceans likely mean new shipping routes will open up, which could lead to an increase of plastic in the Arctic, she added.

"It's a problem that's going to get worse as the Arctic Ocean becomes more water and less ice," said Obbard.

Local concerns

Cozar said this is a global problem — even the most environmentally conscious person living in the Arctic can't escape pollution coming across the globe.

"We think of these polar regions as these very distant, very pristine environments," said Jennifer Provencher, a post-doctoral researcher at Acadia University in Wolfville, N.S. "And increasingly we know that that's just not true."

"Most humans live in temperate regions and towards equatorial regions, and yet our pollution is not staying in those kind of geographical bounds — they're moving beyond into these remote regions."

The plastic pollution can have a very real impact on food security, said Provencher.

Because of currents, the Canadian Arctic has less plastic than other parts of the Arctic. But migratory birds like fulmars, for example, are known to ingest plastic floating in the North Atlantic where they spend their winters.

"When they're flying back into the Canadian Arctic each spring, they're bringing that plastic burden with them," said Provencher.

And the plastic is ingested right up the food chain, which leads to questions about food security and traditional rights, especially in areas where subsistence or traditional hunting is common practice.  

Obbard said she was contacted by a teacher in Ulukhaktok, N.W.T., who said people in the remote Arctic community cut ice from the sea and then melt it for drinking water.

"And they have seen microplastics in that ice," she said.

Efforts to stem the plastic tide are happening, such as the ban on micro-beads in cosmetics, and continual pushes to ban single-use plastic bags.

And Cozar said it's crucial that waste is managed at the source.

"Because once plastic enters the ocean, its destination and impacts are uncontrollable," he said.