Plumer writes: "The vast majority of plastic trash ends up in landfills, just sitting there and taking thousands of years to degrade."
A boy digs through garbage in the Pacific Ocean. (photo: AFP/Getty images)
13 February 15
hat happens to all our plastic bottles and lids and containers after we toss them out?
The vast majority of plastic trash ends up in landfills, just sitting there and taking thousands of years to degrade. A smaller fraction gets recycled (about 9 percent in the United States).
But there's another big chunk that finds its way into the oceans, either from people chucking litter into waterways or from storm-water runoff carrying plastic debris to the coasts. And scientists have long worried that all this plastic could have adverse effects on marine life.
Now we can finally quantify this problem: A new study in Science calculates that between 5 and 13 million metric tons of plastic waste made it into the ocean in 2010 alone. What's more, the authors estimate this amount could more than quadruple by 2025 without better waste management.
And here's another surprise twist: We still don't know where most of that ocean plastic actually ends up. A separate study last year in the Proceedings of the National Academy of Sciences identified massive swirling garbage patches in each of the world's oceans that contain up to 35,000 tons of plastic.
Yet those patches accounted for less than 1 percent of the plastic thought to be in the oceans — and no one quite knows where the other 99 percent went. One possibility is that marine creatures are eating the rest of the plastic and it's somehow entering the food chain. But that's still unclear.
China accounts for one-quarter of plastic ocean waste
The new Science study, led by Jenna R. Jambeck of the University of Georgia, was the first since the 1970s to try to quantify how much of our plastic waste on land ends up in the ocean each year.
The authors looked at plastic production rates, data on waste management and disposal in 193 different coastal countries. Putting this all together, they estimated that the world threw out 275 million metric tons of plastic waste in 2010 (much of it from plastic packaging).
They then estimated that between 4.7 and 12.7 million metric tons made its way to sea — with a best estimate of 8 million tons. That's enough to cover the world's entire coastline.
China was the biggest contributor by far, accounting for roughly one-quarter of the marine debris produced each year. (Note that these figures only include plastic waste on land that makes its way to sea. It doesn't include things like plastic waste from fishing vessels, which makes up an unknown fraction.)
What's more, the researchers find, the amount of plastic waste could quadruple (or worse) by 2025 unless better waste-management techniques are adopted — like recycling or a reduction in packaging materials used.
Every ocean now has a massive plastic garbage patch
So where does this ocean plastic go?
Many people have heard of the Great Pacific garbage patch — a massive patch of trash that's accumulated in a swirling subtropical gyre in northern Pacific Ocean. Ocean currents carry trash from far and wide into this vortex.
And it turns out that there are at least five of these floating garbage patches around the world. That's according to a separate 2014 study in The Proceedings of the National Academy of Sciences, led by Andres Cózar of the Universidad de Cadiz based on the results of a 2010 circumnavigation cruise.
These garbage patches aren't visible from up high — or even from a passing boat — since most of the plastic is bobbing just beneath the surface, and most of the particles are smaller than 1 centimeter in diameter. Over time, the plastic bits get broken down into ever smaller pieces as they get battered by waves and degraded by the sun.
Even so, these gyres have a lot of garbage, collectively holding some 7,000 to 35,000 tons of plastic in all. The patch in the North Pacific was by far the biggest — containing about one-third of all the floating plastic found. (Much of the plastic debris from eastern China, for instance, collects here.)
And yet, what was most surprising to researchers was that these plastic garbage patches weren't even bigger. There should be millions of tons of plastic in the oceans. But these subtropical gyres only contained up to 35,000 tons. In particular, there seemed to be much less plastic smaller than 1 millimeter in diameter than expected. So where did the rest go?
99% of plastic in the ocean is missing. Where did it go?
In the PNAS paper, the authors offer a couple of possible explanations for why they didn't find nearly as much floating plastic as they expected. The most troubling is that fish and other organisms are eating all the plastic:
Either way, something doesn't add up — the current numbers suggest that the vast majority of plastic trash in the ocean is vanishing, and no one seems to know where it went.