Plastic seems to be everywhere in our lives and, according to new research, it has also become a ubiquitous part of the world's oceans.
An international team of scientists joined forces to survey the expansive array of plastic items found afloat in the seas. What they found was everything from buoys and bags to polystyrene pieces and microplastics, totaling about 268,940 tons. The figure does not even include plastic that washes up on beaches and seashores, floats in the water column, or sinks down to the seabed.
Many researchers, journalists, and photographers have documented the Great Pacific Garbage Patch and other waste islands, as well as the increasing amounts of microplastics in the water. But the weight and abundance of global ocean plastic pollution has been hard to quantify, particularly in the Southern Hemisphere.
"There's a vast amount of this stuff in a place it doesn't belong," Kara Lavender Law, principal investigator with Plastics at SEA, told VICE News.
The irony of petroleum-based plastics is they were designed to be long lasting but are now the de facto choice of disposable packaging. Every year, 280 million tons of plastic is produced, according to the nonprofit Algalita, a marine research institute.
'You are what you eat and what you eat is coming from an environment with trash floating in it.'
About half of the plastic produced makes its way to the landfill and less than 10 percent is recycled, according to the 5 Gyres Institute, a non-profit that works to eliminate plastic pollution. Some items are durable goods that are used for the long-term. But the rest finds its way into the environment as pollution — often ending up in the water.
The group of ocean researchers took 24 expeditions in international waters, costal regions, and enclosed seas, such as the Mediterranean, scouring the surface with nets or making visual estimates of the number and weight of plastic objects in the water. They then made models to estimate the total amount of plastic in the oceans. Their findings, which provide a baseline for future research, were published December 10 in PLOS ONE.
Although large items make up more of the weight of ocean trash, it is microplastics that truly plague the oceans. Microplastics, defined as 0.33 to 4.75 millimeters, comprised about 92 percent of the more than five trillion particles estimated in the study.
Model results for global count density in four size classes. Model prediction of global count density (pieces per square kilometer; see colorbar) for each of four size classes (0.33-1.00 mm, 1.01-4.75 mm, 4.76-200 mm, and >200 mm).
No part of the world's waters have been spared, but the North Pacific is the worst affected by plastic pollution. The North Pacific has a little more than a third of the total plastic found in the oceans. The PLOS ONE study's findings were similar to a previous study that found the total microplastic load of just the North Pacific was about 35,000 tons.
"That's encouraging that two very different approaches are coming up with a very similar number," Law told VICE News.
The figures are conservative, Captain Charles Moore, one of the paper's coauthors and founder of Algalita, told VICE News. For large floating debris, each piece was estimated to be about a third of an ounce. But Moore said about 90 percent of the pieces he's weighed for other studies was "way more" than that — and sometimes more than a pound. The modeling also took conservative estimates of the amount of plastic waste from urban areas that washes into the ocean.
In the Southern Hemisphere, the study found the Indian Ocean has more pieces of plastic than the South Atlantic and South Pacific oceans combined. What surprised the authors in this study was there is nearly as much total plastic in the Southern Hemisphere as there is in the Northern Hemisphere, even though there are far more sources of plastic pollution in the Northern Hemisphere. The Southern Hemisphere, which includes many rapidly developing nations, like Indonesia, are quickly catching up, said Moore.
But there is far less data for the Southern Hemisphere, and so the findings from this study should be interpreted with caution, said Law.
Model results for global weight density in four size classes. Model prediction of global weight density (pieces per square kilometer; see colorbar) for each of four size classes (0.33-1.00 mm, 1.01-4.75 mm, 4.76-200 mm, and >200 mm). The majority of global weight is from the largest size class.
Researchers know that larger pieces of plastic are broken down into increasingly smaller and smaller pieces. Some is broken down through UV degradation. Other plastic undergoes biodegradation, a process where microorganisms break down the chemicals that make up the plastic. But more often it is marine life - from fish to birds to mammals — that ingests the plastic trash that is everywhere.
For years consumers have been warned about specific plastic items harming charismatic ocean mammals, such as turtles, being caught in the plastic rings that hold six packs of soda or beer. But now researchers know that everything from small invertebrates to large predators are ingesting plastic. And scientists are increasingly asking how much of it is not just impacting aquatic life but also the seafood that finds its way to our plates.
"You are what you eat and what you eat is coming from an environment with trash floating in it," said Law. She cautioned that there is still a lot of research that needs to be done to better understand how plastics might transfer to animal tissue that animals eat. There is also research to better understand how plastics absorb other contaminants in the ocean, such as DDT, and whether that can transfer to the organisms that eat the plastic.
"There's a natural reason to be concerned," Law told VICE News.
So far, global estimates have only looked at the trash on the surface and not the total amount suspended in water or sitting on the bottom. Many types of plastic are certainly further down, either because they break down on the ocean's surface or because many types of plastic resins don't float at all. Moore told VICE News about one third of fish his expeditions have surveyed have ingested plastic.
To curb the amount of plastic that makes its way into the ocean, Moore said those that produce the plastic, half of which goes to packaging, need to be responsible for it.
"So, if you can't imagine vacuuming the planet from Tierra del Fuego to Northern Canada, just think: Cleaning the ocean would be much more difficult," Moore told VICE News. "Society needs to make things that don't require cleanup."
Follow Katherine Tweed on Twitter: @katherinetweed