Between five and 13 million tons of plastic garbage found its way into the world's oceans in 2010, say researchers, who warn that this amount could increase tenfold in the next decade unless action is taken soon.
It's difficult to picture what all that plastic waste looks like, the researchers say it amounts to about five grocery bags of plastic waste for every single foot of coastline in the world.
Put another way, 8 million tons -- the midpoint of the estimate -- would cover an area 34 times the size of Manhattan ankle-deep in plastic waste.
That's according to study co-author Roland Geyer with the school of Environmental Science & Management at UC Santa Barbara and study lead Jenna Jambeck, an environmental engineer from the University of Georgia.
If trends continue, the annual output of plastic into the oceans will have grown to twice the 2010 levels by 2025, write the authors in Science.
Several studies in recent years have pointed to the vast problem of plastic waste accumulating in our oceans. A study in December found the majority of the waste is made up of "microplastic" measuring less than five millimetres across. These microplastics get eaten by small organisms such as plankton and are then passed up the food chain to larger predators, including humans.
The plastic that's not eaten collects in huge patches of debris on the ocean's surface, pushed together by ocean currents. One of the largest of these, the "great Pacific garbage patch," is roughly the size of Texas.
Scientists know they don't even have a good estimate of how much plastic is in the ocean, because all they can measure is plastic that floats. But they know there is likely plenty of plastic sitting on the bottom of the ocean, as well.
Once plastic waste makes its way into the oceans, it becomes too cost-prohibitive to attempt to remove it on any large scale, say the authors.
"This means that we need to prevent plastic from entering the oceans in the first place through better waste management, more reuse and recycling, better product design and material substitution," Geyer said in a statement.
The other arm of the solution is to ensure that garbage that is created every year is properly disposed of.
The researchers say that "uncaptured waste" -- trash that is littered or lost from waste management systems and then makes its way to coastlines is a huge problem, particularly in lower-income nations. In fact, after looking at data on waste from 192 coastal countries, the researchers say mismanaged waste is the biggest source of the plastic debris that ends up in our planet's oceans.
The researchers found that the largest quantities of plastic waste came from a relatively small number of rapidly developing countries. In fact, the top 20 countries on their list accounted for 83 per cent of the mismanaged plastic waste that enters the ocean.
Some of the worst offenders include:
- China
- Indonesia
- Thailand
- Vietnam
While the numbers are staggering, the authors say the problem is not insurmountable and current trends can be reversed.
"We need to make sure that we are collecting and capturing solid waste and plastic around the world," Jambeck said.
"Second to this is what we do with it... If we at least capture it, it's not going to go into the oceans."
