Boyan Slat’s Ocean Cleanup: It’s Not Going to Work

I first heard of Boyan Slat and his plans to clean up the North Pacific Gyre when I was in the North Pacific Gyre. I was there with thirty-seven others aboard the SSV Robert C. Seamans in 2012. We were taking part in Plastics at Sea, a six-week scientific expedition conducted by Sea Education Association. We discussed Slat’s proposed Ocean Cleanup around the table after dinner one evening. It would involve surface booms one hundred kilometers long, anchored to the ocean bottom. These would corral floating plastic to a central platform where it would be removed, stored and eventually taken away by ships. From land it might seem like a plausible plan. From the middle of the ocean, it was clearly impossible.
We didn’t think we’d hear any more about Boyan Slat or his Ocean Cleanup. We were wrong. Since then Slat has been piled with accolades including Most Promising Young Entrepreneur, Champion of the Earth, Global Thinker. A TED Talk on his plans to clean up plastic in the North Pacific Gyre went viral. Millions have been raised on social media to support his effort. His Ocean Cleanup continues to be the topic of glowing news stories. Too many people are still saying that Boyan Slat is going to take care of plastic in the ocean. It is time to respond.

The North Pacific Gyre is a hard place to get to. The waves and weather can be nauseatingly fierce. The bottom is three miles down. These conditions create extremely tough technical problems, and critics have already pointed to lots of valid reasons why Ocean Cleanup won’t work in this environment. But let’s say Boyan Slat is able to successfully deal with middle-of-the-ocean conditions and install Ocean Cleanup. It still won’t rid the ocean of plastic because most of the plastic in the Gyre is too small to be removed with his invention, and all the gyre’s plastic, large and small, is inextricably mixed in with life.

Boyan Slat claims that Ocean Cleanup will be able to remove plastic that is larger than two centimeters across. Most people imagine that the ocean is full of large, recognizable pieces of plastic, but it’s not. What were once milk jugs, cigarette lighters and bottle caps fragment into tiny specks the size of zooplankton. The currents in gyres slowly suck floating plastic in and then hold it for a long time. The plastic doesn’t go away, but it does break into smaller and smaller pieces.

There is an alarming amount of plastic in the ocean, but the vast majority is smaller than two centimeters. Ocean plastic is sampled with fine-meshed nets that are towed along the ocean’s surface. We removed almost 70,000 pieces of plastic from net tows from the 2012 cruise using tweezers because fingers are too big and clumsy. Some plastic is so small it passes through the net. To collect and study the small stuff, water is collected, then the plastic and other tiny particles are filtered out and counted underneath a microscope.

The ocean is full of life as well as plastic. Our nets pulled up both plastic and zooplankton, and it took effort and tweezers to separate the two. Zooplankton are a diverse group of tiny animals that drift with ocean currents. They occupy a low but crucial rung on the ocean food chain. They are food, or their predators are food for most other animals in the sea.

Slat claims that most zooplankton will safely swim beneath the 3 meter deep barrier of his Ocean Cleanup, but many of these animals can only survive on the surface. Halibates is an insect that scoots on top of the ocean held up by water’s surface tension. You can find it a thousand miles from land, but it doesn’t swim. Vellela, the by-the-wind-sailor, has a stiff sail that pokes into the air above and propels this zooplankton across the ocean, but it doesn’t dive. Janthina is a beautiful purple snail that floats on the surface suspended by a raft of bubbles. If the bubbles burst, the snail sinks to its death. Slat says the biomass (weight) of any zooplankton lost to Ocean Cleanup will quickly be replaced by biomass of new life — any life. But zooplankton is much more than the sum of its biomass. Our knowledge of the different types of zooplankton, their interactions with the environment and other species, and the importance of particular zooplankton in the grand scheme of ocean life is too sparse to upset the balance in a way that Ocean Cleanup’s 100 km long barriers would.

Mike Gil was a doctoral candidate aboard the Siemens who studied the organisms found on larger pieces of floating plastic. He scooped up the big pieces then removed and identified the animals to see which species were using the plastic as rafts. Larger pieces of plastic in the Gyre are encrusted with barnacles, anemones, crabs and other life that latch on to any solid structure they find and form mini floating ecosystems.  Gil explains: “Removing the diversity of critters that make homes out of large plastic debris in the ocean is no easy task–we’re talking paint scrapers along with a lot of time, sweat and patience.”

Ocean Cleanup will not rid the sea of plastic. If it ever gets out of the drawing room and into the ocean, it is more likely to harm life than protect it. Boyan Slat is clever, bold enough to take on big problems and great at raising money. He’s young too. He has time to tinker on a small scale and sort out what works from what doesn’t work. He may come up with excellent solutions one day.

We don’t need to wait for the day when a big fix may appear. We can get plastic out of the ocean right now by removing it when it washes up on beaches. Boyan Slat claims that Ocean Cleanup will be 7900 times faster and 33 times cheaper than removing plastic from the beach. He may have the math wrong. Picking up plastic from the beach is really simple. BlueTube makes it even easier. Grab a bag from the BlueTube at your beach, pick up trash, throw it away. Remember to donate your extra clean, used bags to the BlueTube on your next trip to the beach so more people can help remove more plastic more often.