Ocean garbage patches bring to mind floating islands where your latest trip to Walmart come back to haunt you. Though nightmarish, they’re not quite what you’d expect.
We want to clear up some of the confusion by sharing seven unique and insightful facts about these amorphous blobs of marine debris in the ocean.
One: In total, 5 gyres collect marine debris
That’s right. A lot of attention has been given to the Great Pacific Garbage Patch, but the North Pacific gyre is not the only gyre where plastic accumulates. Five different gyres shape the currents of the oceans and create predictable final destinations for plastic.
In 2013, of the roughly 297 million tons of plastic floating on the surface of the ocean, the distribution across the gyre-regions was as follows:
- North Pacific (36 percent)
- Indian Ocean (22 percent)
- North Atlantic (21 percent)
- South Pacific (8 percent)
- South Atlantic (4.5 percent)
The remaining 8.5 percent stayed in the Mediterranean Sea (OWID).
Where are the 5 great garbage patches located?
There are north and south gyres in the Pacific Ocean, as well as north and south gyres in the Atlantic Ocean. The fifth gyre circulates in the southern part of the Indian Ocean.
What is an ocean gyre?
Gyres are circulating patterns of ocean currents that produce the still waters where plastic accumulates in “patches.” People sometimes refer to garbage patches as gyres, when in fact garbage patches just result from gyres. These complex circulating patterns teach us a lot about how the different regions of the ocean stay interconnected in spite of the vast distances between them.
How do ocean gyres work?
With the bookends of the land masses, the momentum of the wind and the pull of the earth’s rotation, gyres form moving patterns that keep the ocean in perpetual motion. The wind cruises over the surface of the ocean, while the rotation of the earth tugs at the ocean waves pushing them at a 45 degree angle.
The waves turn towards the right in the Northern hemisphere and they turn towards the left in the Southern hemisphere. This wave-altering motion is known as the Coriolis effect. As the Coriolis effect causes the surface waves to descend into the ocean, the angle gradually tapers off and this shift creates a spiraling motion called an Ekman spiral.
Except for the more complex Indian Ocean gyre, the other ocean gyres circulate either in a clockwise or counterclockwise motion in the subtropical regions of either the Northern or Southern hemispheres. This motion performs useful functions by controlling the temperatures, nutrient flows, and salinity of the oceans. The ocean current cycles around a mostly calm and motionless center.
Two: Most marine debris goes to the 5 gyres from just 10 rivers
According to a recent scientific study, roughly ninety percent of the plastic in the ocean comes from just one of ten rivers in the world, five of which pass through China:
- Chang Jiang (Yangtze River) (1.5 million tons) Asia’s longest river, this Chinese river flows to the southern part of the Yellow Sea, which accesses the Pacific.
- Indus (160,000 tons) This river enters the Indian Ocean from Pakistan.
- Huang He (Yellow River) (120,000 tons) The second longest river in China which leads to the Pacific via the Yellow Sea.
- Hai He (92,000 tons) A river system in the northern part of China that flows into the Bohal Sea.
- Nile (85,000 tons) The longest river in the world, which flows through Egypt to reach the Mediterranean Sea.
- Meghna, Brahmaputra, Ganges (73,000 tons) The Ganges river basin flows out to the Bay of Bengal, reaching the Indian Ocean
- Zhujiang (Pearl River) (53,000 tons) The Pearl River flows through China to the South China Sea
- Amur (38,000 tons) The Amur River forms part of the border between Russia and China, and it leads to the Sea of Othosk.
- Niger (35,000 tons) The Niger River flows through West Africa to the Gulf of Guinea on the coast of Nigeria
- Mekong (33,000 tons) The Mekong River flows through Southeast Asia past Laos, Thailand and Cambodia, emptying into the South China Sea.
The study correlated the incidence of mismanaged plastic waste to the high level of inflows of plastic and other debris to the oceans.
Where does marine debris come from?
Eighty percent of marine debris comes from land-based sources, while the rest comes from vessels navigating the oceans. These ships discard materials such as large fishing nets.
Three: Most of the world's marine debris doesn't float, it sinks
When you look up garbage patches, some photos show the densest parts of the plastic patches where large pieces of plastic bob on the surface of the water. However, these photographs only capture the most obvious form of plastic pollution and they don’t tell the full story of marine debris.
According to a June 2016 report by Eunomia titled “Plastics in the Marine Environment,” only 1% of plastic in the ocean floats on the ocean surface. On average, global concentrations at the surface of the ocean are less than 1kg/km2, while at the most dense places like the North Pacific Gyre, the concentration reaches 18kg/km2. In fact, 94 percent of plastic eventually sinks to the ocean floor, creating an ecological issue that’s quite difficult to study, due to its depth.
Consumer plastics generally fall just above or below the threshold of material density needed to float. The only plastics that float in ocean water are polyethylenes used in most packaging and polypropylenes used for things like yogurt cups, microwavable dishes and disposable diapers. The rest automatically sink.
However, even lightweight plastics are also believed to sink overtime as other organisms and microbes attach to them, weighing them down. Plastics then behave differently depending on whether they fall to the continental shelf where the ocean current shuffles them around, sometimes kicking them back up to seashores.
This is why beaches tend to have a density of plastics five times higher than the ocean surface on average. Much of the beach plastic you find may have first visited the continental shelf before coming back to shore.
The largest percentage, however, falls to the deep ocean floor, where plastic rests with no likely chance of returning to sight. We’re talking an average of 70kg of plastic covering each square kilometer of the ocean floors.
Four: The size of the Great Pacific Garbage Patch changes constantly
Considering the nature of how plastics float and sink, it’sdifficult to estimate the size of the ocean garbage patches, as they’re in flux. Moreover, most of the plastic in these patches is so small, it can’t be seen by the naked eye.
The largest patch of plastic is located somewhere between California and Hawaii in the North Pacific Gyre and it is usually referred to as the Great Pacific Garbage Patch (GPGP). The estimated size spans a surface area roughly three times that of France and two times that of Texas: 1.6 million square kilometers.
In 2018, the Los Angeles Times reported that the size of the GPGP had increased to a total of 1.8 million pieces of plastic weighing roughly 87,000 tons. Scientists are alarmed not just about the size of the patch, but its rate of growth.
A sampling of the material in the GPGP showed that 94 percent of the 1.8 million pieces of plastic in the GPGP are microplastics accounting for just 8 percent of the plastic by weight. Most of the plastic by weight were larger pieces of plastic, with fishing nets accounting for 46 percent of the plastic in the GPGP.
Can you see the great pacific garbage patch from space?
Unfortunately, neither satellites nor Google Earth will give you a clear glimpse of the Great Pacific Garbage Patch. The pieces of plastic don’t collect like cheerios in a bowl of milk. They’re more like the sediment that fills muddy water, giving the ocean more of a hazy, smoggy quality. The concentration is not high enough to be easily seen in most parts of the ocean.
Five: Here's how the Great Pacific Garbage Patch was discovered
Captain Charles Moore, a California-based yachtsman noticed an unnatural accumulation of plastic in the Pacific Ocean when he was returning from the biennial Transpacific Race.
His path crossed directly through the calm waters of the North Pacific subtropical gyre in 1997. That year was the same year climatologists had pointed out the highest El Niño weather pattern on record. It made the surface of the Pacific warmer and calmer than usual.
However, Moore didn’t realize the extent of the plastic problem until he returned in 1999 to understand the size of the garbage patch, which had grown since his previous journey.
As a result of his discovery, he raised public awareness about the issue. He used the Algalita Foundation, an organization he started in 1994 to improve the cleanliness of California’s coastal waters, to raise awareness and conduct research about ocean plastic.
Six: A French man decided to swim through the Great Pacific Garbage Patch
Brian Lacomte, a 51-year-old swimmer who literally goes great lengths to cross oceans, is in the midst of a swim from Hawaii to San Francisco. His route crosses directly through the Great Pacific Garbage Patch and he’ll swim about eight hours per day before climbing aboard a support ship following him. His goal? To shed light on the glut of ocean plastic collecting in the ocean gyres.
He previously made a Transatlantic swim in 1998 lasting 73 days. Last year, he attempted crossing the entire length of the Pacific Ocean with a starting point in Japan in a publicity stunt called “The Swim.”
However, after a severe storm damaged the main sail of his ship, his team had to stop “The Swim” and come up with a plan B. He did manage to complete a stretch of 1,500 nautical miles before the storm hit.
The current stretch charts 300 nautical miles through the part of the Pacific most densely littered with plastic debris. His swimming equipment includes goggles, a wet-suit and diving fins.
Seven: The Ocean Cleanup has started
An Netherlands-based organization launched it’s plan to clean up the plastic on the surface of the ocean in September of 2018. The company, called The Ocean Cleanup, aims at reducing fifty percent of ocean plastic debris every five years using floating trash collectors. The goal is to upcycle the collected materials into new products for sale, while protecting sea birds and other wildlife from ingesting plastic.
The non-profit organization is led by a 24-year-old inventor named Boyan Slat, who dropped out of university to pursue his vision in 2013. The organization raised $31.5 million dollars of investment and gained widespread public attention through TEDx talk that received 2.5 million viewers.
However, skeptics of the project raise concerns about the nature of the project. First, it doesn’t get to the root cause of ocean plastic, which is plastic consumption. Second, the first deployed rig of the project faced technical difficulties because some of the plastic it collected floated back to sea, because it moved too slow to capture them.
Finally, many scientists argue that collecting surface plastic can disrupt the ecosystem which has adapted to the onslaught of plastic and the greater ocean plastic concern of microplastics can’t be collected from the ocean’s surface. Nevertheless, the project continues to troubleshoot its engineering difficulties.
Why technology won't save us from ocean plastic
In spite of our best efforts to patch up the problem of marine debris, the garbage patches collecting in the gyres are too big to face with technology. The source of the problem starts with our over consumption of plastic.
We use it for disposable packaging and the cheapest appliances and toys we can find. Yet, the cost of plastic is much higher when you account for its afterlife in the waste stream, which is nearly immortal.
That’s why the only way to truly solve the dilemma posed by the garbage patches is to start at the source and reduce our consumption of plastic.
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