This plastic bottle cap didn't begin life here it had to travel a long way to reach
the middle of the ocean. How does plastic end up here, and where does it go? Plastic is one of the
largest threats our oceans face today, and over the past 10 years our scientific understanding
of the problem has evolved a lot. This is how we understand ocean plastic pollution today.
Plastic is a cornerstone of our modern civilization. Every year, we produce more
than 400 million tons of it; that's about the same as the weight of all human beings on planet Earth.
The amount of plastic we're producing is growing exponentially, yet only a tiny fraction of it
makes it to the ocean. Most of the plastic is only used briefly and discarded afterwards.
The majority is safely collected and prevented from moving around freely in the environment
more than half of it goes to landfills and the rest is incinerated or recycled.
However, about 20 percent is either not collected, improperly disposed of, or ends up as litter.
Plastic usage and waste management infrastructures differ all over the world; people in high income
countries consume the most plastic but the waste management systems there are usually
effective. Whereas in many low-income countries plastic consumption is low
meaning emissions remain low even if the waste management infrastructure is lacking.
The majority of plastic emissions come from middle income countries whose plastic usage is growing
but that are lacking adequate waste management systems to deal with the increase in consumption.
Most of the plastic stays on land, but let's say a bottle was left on a city street close to a river -
suddenly, it starts raining heavily and the wind picks up. In these conditions,
our bottle has a real chance of ending up in the river. During
storms and other heavy rain events plastic emissions can increase as much as tenfold.
Rivers are the arteries that carry the plastic from land to sea but not all plastic that ends up
in rivers will make it to the ocean. Many plastic objects sink or get stuck in the river system
The closer the plastic is to a river, and the closer that river is to the ocean, the greater
the chances that the plastic will reach the ocean. Therefore, coastal cities and
middle-income countries are the world's plastic emissions hot spots. A recent study shows that
1 000 Rivers worldwide represent almost 80 percent of plastic emissions into the oceans.
So, let's say our plastic bottle ended up in one of these rivers and is on its way out to sea
Most floating plastic doesn't stay in the ocean, about 80 percent will beach
on a coastline within a month, some of it may be washed out to sea again but
coastlines are the final resting place for most plastic that enters the oceans.
This can have serious consequences for the coastal environments, the fishing and
tourism Industries, as well as resulting in heavy cleanup costs for coastal communities.
Some plastics will stay afloat but another fraction will sink, such as our pet bottle for
example, while the bottle itself sinks the cap will stay afloat for much longer, polluting our
coastal waters. It can take years for a plastic piece to break free from these coastal waters
and be carried out to the open ocean, but once it's out there it can stay there for a long, long time.
Plastic accumulates in huge subtropic oceanic areas called gyres - massive circular currents
that trap the plastic for decades if not centuries. There are five gyres in our oceans
the most polluted and best studied is the infamous Great Pacific Garbage Patch located in the North
Pacific Ocean between Hawaii and California. Today around 100 million kilograms of plastic float in
the Great Pacific Garbage Patch with a plastic count of about 1.8 trillion pieces dispersed over
the ocean. The area of the Great Pacific Garbage Patch is estimated to be twice the size of Texas
that's triple the size of France or Thailand.
Rivers are the main source of ocean plastic pollution but there is a second source -
fishing gear. While most plastic in coastal waters comes from land-based sources the
garbage patches are different. In fact, about 80 percent of the plastic in the Great Pacific
Garbage Patch comes from fishing activities at sea. Fishing equipment lost or dumped at sea
has a much higher chance of accumulating offshore because it is emitted away from
coastlines and fishing gear is designed to survive in the water for long periods.
About 92 percent of the floating plastic mass in the Great Pacific
Garbage Patch consists of larger objects only about eight percent are microplastics.
Plastic pollution doesn't go away by itself; the oldest piece is found date back to the 1960s
degradation is very slow but constant so the largest objects are a ticking time bomb
breaking down over time and raising levels of microplastics exponentially. Animals often
consume plastic particles mistaking them for food; not only is this incredibly damaging to
the animals but this allows toxic chemicals to enter the human food chain, potentially impacting
the health of around 3 billion people who rely on seafood as their primary source of protein.
Plastic pollution in the ocean is a planet-sized problem. As we've seen, every year more than 400
million tons of plastic is produced; however, less than half a percent ends up in the ocean
most Plastics stay on land. Ocean plastic pollution is highly concentrated and comes from only a small
number of possible leakage points. This is the best understanding of ocean plastic pollution to date.
As research continues with hundreds of scientists around the world working on this issue, we are
bound to discover even more in the years to come.