GYRES AND GARBAGE PATCHES

The plastic litter defacing the beaches of the World, alarming in Hawaiian archipelagos for instance, led, only two decades ago, a couple of private and public teams of environmentalists and scientists to start conducting research regarding marine debris in the oceans.

Between 1985 and 1988, an Alaska- based team of researchers found high concentrations of marine debris accumulating in regions governed by vortices like pattern of ocean currents, which lead the National Oceanic and Atmospheric Administration (NOAA) of the United States to publish a paper, in 1988, mentioning the high probability of the existence of “a large area highly concentrating plastic waste debris in the North Pacific”. Flyovers of the area have been conducted as well, but not in a conclusive way. The trash was not that obvious from the sky. Indeed, despite its size and density, the GGP is not visible from satellite photography because of its consistency, as Kaisei project and Scripps teams confirmed last August. The largest mass of the plastic pollution contains fragmented pieces of plastic, permeating the ocean, almost invisible to the naked eye, suspended at, or beneath the surface of the ocean.

Plastic soup. Photo: Charles Moore

As evoked above, Charles Moore, a Californian sailor, surfer, volunteer environmentalist, and researcher, was crossing the Pacific Ocean while returning from a trans Pacific sailing race in 1997. He veered from the usual sea route taking a shortcut across the edge of the North Pacific Ocean. He came upon an area, the Doldrums, a windless part of the ocean that mariners usually avoid. The area is filled with tiny phytoplankton, but few big fish or mammals, thus fishermen and sailors rarely travel through it. There, Charles Moore saw an ocean he had never known. Every time he stepped out on deck, “there were shampoo caps and soap bottles and plastic bags and fishing floats as far as I could see. Here I was in the middle of the ocean, and there was nowhere I could go to avoid the plastic.”

This area that Charles Moore came upon, the North Pacific Subtropical Gyre, is a slowly moving, clockwise spiral or vortex of currents created by a high-pressure system of air currents. He reported his find to Curtis Ebbesmeyer, an oceanographer, who named it the Eastern Garbage Patch.
Shocked by the extent of the plastic litter, Charles Moore went on alerting the world to the existence of this phenomenon.

Moore’s discovery was finally corroborating previous scientists’s, suspicions and extrapolations in regard to the existence of a high debris concentration in stable bodies of oceanic waters created over time by the rotating ring-like ocean currents system called gyres.

“We were out in the middle of the Pacific, where you would think the ocean would be pristine,” recalls the Alguita’s captain, Charles Moore. “…And instead, we get the Exxon Valdez of plastic-bag spills.”

Captain Moore’s giant floating debris field’s discovery has since been subject to other expeditions, and another “patch” was found further west.

Media light was finally brought in force at that point. Human kind has walked on the moon since 1969…yet the ocean was still quite an unknown frontier in our collective conscience.

Gyres

The North Pacific gyre has given birth to two large masses of ever-accumulating plastic debris, known as the Western and Eastern Pacific Garbage Patches, collectively called the Great Pacific Garbage Patch (GGP). It is a gyre of marine litter in the Central North Pacific Ocean stretching for hundreds of miles across the ocean 1,000 miles from California coast on the East, to Japan and Hawaii on the West.

More specifically, a gyre is a large-scale circular feature made up of ocean currents that spiral around a central point, clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Gyres make up to 40 percent of the ocean. That is 25 percent of the globe. All of them are accumulators of debris, Moore says.

Worldwide, there are five major subtropical oceanic gyres: the North and South Pacific Subtropical Gyres, the North and South Atlantic Subtropical Gyres, and the Indian Ocean Subtropical Gyre. Since each behaves in the same vortex style, scientists are certain that massive conglomerates of marine litter like the North Pacific Garbage Patch exist in each of the world’s oceans. That is soberingly self-explanatory: such huge garbage patch, or even larger ones, are more than likely to be discovered in the near future.

North Pacific Gyre. Illustration: NOAA

It is very difficult to measure the exact size of a gyre because it is a fluid system, but the North Pacific Subtropical Gyre is roughly estimated to be approximately 7 to 9 million square miles, approximately three times the area of the continental United States (3 million square miles). Gyres do potentially aggregate debris on that large a scale. That is titanic.

Upon returning from their 22 days venture on the GGP, Project Kaisei and Scripps scientists’ stated in a press conference held in September 2009: “(we) hope our data gives clues as to the density and extent of marine plastic debris, especially since the Great Pacific Garbage Patch may have company in the Southern Hemisphere, where scientists say the gyre is four times bigger. “We’re afraid at what we’re going to find in the South Gyre, but we’ve got to go there,” said Tony Haymet, director of the Scripps Institution.

Garbage Patches

The Great Garbage patch is two separate accumulations connected by a 6,000-mile marine litter “corridor” known as the North Pacific Convergence Zone (STCZ). As will be explained infra, the convergence zone is in itself another serious accumulator of traveling plastic debris.

The Eastern Pacific Garbage Patch floats between Japan and Hawaii; the Western Patch floats between Hawaii and California. The rotational pattern created by the North Pacific Gyre draws in waste material from as far as Asia to the USA. As material is captured in the currents, wind-driven surface currents gradually move floating debris inward, trapping debris in higher concentrations in the calm center. Ocean currents carry debris from the East coast of Asia to the center, in less than a year, and from the Western US in about 5 years.

North Pacific Subtropical Gyre. Illustration: Greenpeace

NOAA has tracked the Great Pacific Garbage Patch movements to some degree. It is not a stationary area, but one that moves and changes as much as a thousand miles north and south, and during warmer ocean periods, known as El Nino, it drifts even further south. The movements occur because the North Pacific Gyre is made up of four different currents: the North Pacific Current to the north; the California Current to the west; the North Equatorial Current to the south; and the Kuroshio Current to the east. This movement sometimes brings the Western Garbage Patch within 500 nautical miles of the California coast and causes extraordinary massive debris pile-ups on beaches, such as in the Hawaiian Islands and Japan.

Great Garbage patch, floating debris. Photo Source: flyaddicts

The name garbage patch has led many to believe that this area is a large and continuous patch of easily visible marine debris items, such as bottles and other litter, akin to a literal blanket of trash that should be visible with satellite or aerial photographs. This is simply not true. While larger litter items can be found in this area, along with other debris such as derelict fishing nets, the largest mass of the debris is small bits of floatable plastic.

We cannot emphasize enough that the GGP is now characterized by extremely high concentrations of suspended plastic debris for 90 percent, basically a soupy mix of plastic-filled seawater, made of tiny plastic debris that have been trapped by the currents and stretching for maybe thousands of miles, and that is the great problem.

Indeed, the researchers from Project Kaisei and the Scripps Environmental Accumulation of Plastic Expedition (SEAPLEX), after their journey through the area, collecting samples the whole way, reported: “All we could see, not at first glance but with magnifying glass and magnifying worries, for miles and miles, was an incredibly huge mass of confetti-like tiny mermaid tears, plastic fragments, floating just beneath the surface. ” As one of the scientist from the Project Kaisei witnessed: “There’s no island, there’s no eighth continent ” Miriam Goldstein said, “It doesn’t look like a garbage dump. It looks like beautiful ocean. But then when you put the nets in the water, you see all the little pieces.” And while the expedition covered 1,700 miles, members of the Kaisei team say the patch could be much, much larger…

As for its depth and assumed density, the scientists reported that the GGP’s waters were just clogged with plastic particles to a depth of 10 meters below the surface. The Scripps/ Kaisei survey mission of the gyre found that plastic debris was present in 100 consecutive samples taken at varying depths and net sizes.

In sum, they estimated the patch area ranged in size from 700,00 km2 to more than 15 million km2; the area may contain over 100 million tons of plastic debris.

Already in 1999, a study by Charles Moore, sampling waters from the GGP, found that the concentrations of plastic there reached one million particles per square mile, topping the concentration of zooplankton (plankton consisting of small animals and the immature stages of larger animals) by a factor of six. In 2008, the published new research from the Algalita foundation team of scientists estimated that the number had doubled.

After the return of the two vessels from Project Kasei and Scripps (Seaplex), Kaisei and New Horizon, the only certainty was that the size of the Great Pacific Garbage Patch remains uncertain. “It’s not a hard and fast number.” There has been extensive media coverage about the garbage patch over the past couple years; however, its reported size and mass have differed from news article to article. “It’s a little bit like a whirlpool on the surface of a river or a lake. You’d be hard-pressed to tell me where the edge is. All you know is that it’s stronger in the middle than it is in the outer reaches. But it’s an area of many hundreds of miles, perhaps thousands, in which the ocean currents tend to bring it together,” according to Robert Knox, deputy director for research at the Scripps Institution.

In the summer of 2010, Project Kaisei will launch its second expedition to the North Pacific Gyre where it will send multiple vessels to continue marine debris research and, in particular, to test an array of larger marine debris collection systems.

Marine debris collection at the GGP. Photo: Lindsey Hoshaw

The Eastern Garbage Patch has been studied the most so far, yet it is not and obviously cannot be the only vast oceanic “rubbish dump out there” says Charles Moore. The GGP is definitely not the only type of area where marine debris concentrates. Several other features within the ocean, including oceanic eddies and convergence zones, can lead to debris accumulation as well. A great and well known example is the North Pacific Subtropical Convergence Zone (STCZ). It is located along the southern edge of an area known as the North Pacific Transition Zone. NOAA has focused on the STCZ because it is an area triggering massive debris accumulation in Hawaii. This area does not have distinct boundaries and varies in location and intensity of convergence throughout the year. This zone moves seasonally between 30º and 42º N latitude (approximately 800 miles), extending farther south (28ºN) during periods of El Niño (Donohue and Foley, 2007).

The August 2009 expedition was so dauntingly successful and the findings were so”shocking”, that “…Scripps’ officials are now working to raise funds for a trip to the South Pacific gyre, sometime within the next two years”, Haymet announced at a press conference last August. “That project’s scope is far greater. While the North Pacific patch appeared as large as the Continental US, its South Pacific cousin is suspected to be about four times as large”, roughly the size of all of Western and part Eastern Europe.