Most of us wouldn’t know where to begin answering the question that frames one of the greatest environmental challenges of our time. Twenty-one-year-old Boyan Slat is not like the rest of us.

When he was just 17 he started the Ocean Cleanup Foundation. His teenage dream was to remove from our oceans a vast mountain of discarded fishing nets, water bottles and other plastic garbage.

Not many people took him seriously at first. He had developed his ideas as part of a school project, he had no money and respected environmentalists said it would take 79,000 years to get all the plastic out of the sea.

A bold prediction

That all changed when he delivered a Ted Talk in his native Netherlands in 2012. He predicted he could clean up the plastic in five years. Some people laughed, others reached for their cheque books.

Four years later Boyan Slat has raised more than $2 million dollars in funding. His organisation is flying a converted military aircraft over the central Pacific, gathering data with an array of sophisticated sensors and cameras.

Image: Ocean Cleanup Foundation

The latest data will stretch Boyan Slat’s optimistic timescale to the limit. His team analysed the data they gathered and concluded the mass of waste known as the Great Pacific Garbage Patch is much larger than previously thought.

Slat told the Guardian newspaper, “Most of the debris was large stuff. It’s a ticking time bomb because the big stuff will crumble down to micro plastics over the next few decades if we don’t act.”

Currents capture plastic waste

The central part of the garbage patch is estimated to cover a million square kilometres. Outlying areas are also filling with plastic waste. These cover another 3.5 million square kilometres.

Image: NOAA

This main island of waste is trapped in a swirling current between California and Hawaii.

The current is known as the north Pacific gyre. It’s essentially an enormous whirlpool that sucks in plastic particles and traps them at its centre.

The Ocean Cleanup Foundation is planning to use the swirling motion that traps the waste as the engine to help clean it up.

Image: Ocean Cleanup Foundation

His team has designed a 100 kilometre long floating plastic boom to scoop up plastic particles.

The idea is to anchor the V shaped boom across the flow of the Pacific Gyre so the current funnels floating plastics into a collecting point. The waste would then be lifted onto ships before being transported by to land where it would be recycled.

A smaller prototype of the boom is being tested in the North Sea. Slat says if it works and can be scaled-up to full size, it could in theory clean up half of the waste trapped in the Pacific gyre in 10 years.

Stopping yet more plastic getting into the sea in the first place is another huge challenge. The world is currently producing more than 300 million tonnes of plastic every year.

The round the world sailor Ellen MacArthur has been conducting her own research into ocean pollution. Her foundation is predicting there will be more plastic than fish in the oceans by 2050 unless serious action is taken to stop plastic waste getting into the sea.