An enormous trash-laden vortex in the North Pacific Ocean delivers plastic debris to Hawaiian Archipelago shorelines, making beach cleanups a never-ending task at Kalaupapa
National Historical Park. Like the urban-industrial air pollution that drifts downwind to afflict many mainland national parks, the marine debris that drifts into the Hawaiian parks from this trashy gyre is an unwelcome invader that the park is helpless to exclude. That's not to say that the problem is insoluble.
Kalaupapa National Historical Park is located on Molokaʻi, a small island just north of Maui. The park was established in 1980 to preserve and interpret the remains of the Kalaupapa Leper Settlement (a National Historic Landmark) and related facilities that were operated from 1866 to 1969 for the care and treatment of Hawaiians suffering from Hansen's disease (leprosy).
Historically known as leper colonies, such settlements were typically situated in remote places in order to isolate victims from the general populace as much as practicable. The northern coast of Molokai's Kalaupapa Peninsula certainly was -- and is -- a remote location. The Kalaupapa settlement sits on a narrow strip of land at the base of cliffs that soar more than 3,000 feet above the sea (roughly the height of Yosemite's El Capitan) and render the place utterly inaccessible by road. At peak operation, Molokai's Hansen's disease settlement was home to around 1,200 men, women and children who lived in what amounted to an island prison.
Marine Trash Comes Ashore
The rest of the world may have a tough time traveling to Kalaupapa, but trash from the rest of the world does not. A single beach cleanup at Kalaupapa National Historical Park last year yielded 300 pounds of trash. This trash, mostly plastic debris, originated far away and was delivered to these shores by wind and waves. It is a common occurrence in many years, and it doesn't happen in just this tiny corner of the Hawaiian Archipelago. On the surfer's paradise that is the north shore of O'ahu, the beach cleanups during 2009 -- representing the collective efforts of 474 volunteers -- yielded four tons of trash and 89,253 separate debris items. Elsewhere, untold amounts of trash continue to wash ashore, much of it ending up in hard-to-get-to places.
The North Pacific Garbage Patches
The source of this shoreline trash is a marine zone that has been dubbed the "East Pacific Garbage Patch," and the delivery system is a set of ocean currents and winds called the North Pacific Subtropical Convergence Zone (STCZ). Most Americans have never heard of these phenomena, or of the problems associated with them, but there's a good chance we'll all be hearing a good deal more about them in years to come.
Over the oceans in subtropical latitudes there are high pressure cells -- great masses of subsiding air -- that move with the seasons, shifting poleward in summer and equatorward in winter. Wind and water currents associated with these high pressure cells move counterclockwise, creating gyres (vortexes) of gigantic size. The North Pacific Subtropical Gyre covers millions of square miles of the North Pacific. Similar gyres exist in the South Pacific, the Indian Ocean, and both the North Atlantic and the South Atlantic.
The North Pacific Subtropical Gyre is actually two great vortexes. One lies to the east and north of the Hawaiian Archipelago (that is, in the direction of California) and the other lies to the west and north (stretching in the direction of Japan.) Both trap huge amounts of floating trash that has been washed or thrown into the sea. The two gyres are commonly referred to as the East Pacific Garbage Patch and the West Pacific Garbage Patch.
Plastic debris is especially abundant because it floats well and is very slow to degrade. However, nobody really knows how much of what kind of trash is in these oceanic garbage patches, or even how much area the patches cover. In fact, the name “garbage patch” is misleading. The trash concentrations are mobile, and also lack clear definition and uniformity. Most of the debris is so small it can't be seen from boats or via satellite imagery and aerial photographs. The water in the gyres also contains high concentrations of chemicals released by the decomposition of the trash, and these might even prove more harmful than the floating debris.
The North Pacific Subtropical Convergence Zone
Connecting the two gyres and their vast collections of debris and chemicals is a 6,000 mile-long system of westward-flowing winds and ocean currents called the North Pacific Subtropical Convergence Zone (STCZ). The STCZ further concentrates floating trash and moves it to the vicinity of the Hawaiian Islands, where some of it ends up on the beaches.
Like the subtropical highs, the STCZ shifts with the seasons and can normally be found between 30° and 42° N latitude. During El Niño periods, however, the STCZ dips equatorward as far as 28°N. That is significant for the Hawaiian Islands. In straying so far to the south, the STCZ delivers significantly more floating debris to Hawaiian beaches during El Niño periods.
For additional details about Hawaii's marine debris problem, visit this NOAA website.
Problems Large and Small
The floating trash and witch's brew of chemicals that the STCZ delivers to Hawaii's nearshore waters and beaches cause many kinds of problems, and littered beaches may be the least of them. Debris entanglements injure or kill many marine birds and mammals every year, including endangered Hawaiian monk seals, sea turtles, seabirds, and whales. How much damage is being done by the biological amplification of harmful chemicals in the food chain remains to be seen, but could very well be severe.
This is not to say that beach litter isn't itself a significant issue. It is unsightly and potentially dangerous. It can be expensive to get rid of, too. At Kalaupapa National Historical Park, where the local landfill is being closed down, the trash collected from the beach will have to be flown or shipped off the island at extra expense.
You Can't Just Address the Symptoms
Unfortunately, no long-term solution is at hand. The oceanic garbage patches are too immense and the mechanical or chemical methods we might be tempted to employ for marine trash removal bear the risk of severely harming wildlife, the zooplankton at the base of the oceanic food chain, and even the phytoplankton that are the vital "grass of the sea." Nothing short of a sea change in our approach to trash generation can hope to resolve the problem of marine debris accumulation. We need to produce less trash and keep it out of the ocean.