By George Harvey
We do not have space here to describe why the Coriolis effect works as it does, but we can note that it is the reason why cyclonic storms have clockwise rotation in the northern hemisphere and counterclockwise in the southern, and high-pressure areas move in the opposite direction to low-pressure areas.
The waters in the ocean behave the same way. The effect of this is that there are areas in the oceans, called “gyres,” which are large eddies. They are numerous, but five are especially large. One, the North Atlantic Gyre, also called the Sargasso Sea, has been known to us since at least the time of Columbus. The other large gyres are in the North Pacific, the South Atlantic, the South Pacific, and the Indian Oceans. All rotate as low-pressure areas, as the water gradually flows toward the middle, and then down to the ocean floor.
Anything floating in the water of a gyre is likely to move toward its center, unless it is blown about by the wind. This means that the gyres collect anything that floats in the water. Particles of plastic and other debris, much of which is so small it cannot be seen without careful examination, float in greater concentrations as it approaches the center of the gyres.
The existence of debris fields in the centers of the gyres was only predicted in 1988 by scientists at the National Oceanic and Atmospheric Administration. They were confirmed less than ten years later.
The waste areas, called the North Atlantic Garbage Patch and the North Pacific Garbage Patch, are many hundreds of miles across. The particles in them are mostly very small. Nevertheless, they are dangerous to wildlife.
Plastic particles often contain long-term poisons. The finest of them are ingested by microplankton, which concentrate them in their digestive systems. These are eaten along with slightly larger plastic particles by larger plankton andsmall fish. These, in turn, are eaten by larger and larger animals until the plastics and their poisons are concentrated in the largest animals. At each stage, larger pieces of plastic are added to the mix.
Seabirds supply fish to their young, providing them with a toxic brew of plastics and poisons. Many are killed. Current estimates are that Midway Island has about twenty tons of plastics wash up on its beaches each year, and about a quarter of these are eaten by albatross and other ocean birds. About a third of the young die, and many of them are victims of the waste floating in the ocean. But even large birds get their intestines blocked by larger bits of plastic.
A study released in early July says that seabird populations have declined by over 70% in the last 60 years. Overfishing is partly to blame. Much of the decline is due to climate change. Some is the result of oil pollution and releases of chemical poisons. Plastic waste and other debris in the Garbage Patches have been major contributors to avian mortality.
We should give thought to where all the toxic junk in the gyres comes from. Surely some of it comes from ships and offshore rigs of one type or another. An appreciable part of it comes from litter at beaches and in rivers. Some is washed down sewers, after it was disposed of improperly. There are about eight million tons dumped in the sea each year. Unfortunately, since nearly all plastics decompose poorly, when a bird or fish dies, the plastic in it is likely to get released into the environment, to kill again.
There are three things we really need to do to stop this. One is to stop using plastics as much as possible. The second is to dispose of them properly or recycle them. The third is to discontinue use of nonbiodegradable plastics wherever possible.
Achieving these goals might be a lot easier if the environmental costs of the plastics we use were included in the original price. Many people would object to such a tax. But the problems we are developing in the environment constitute a hidden tax imposed on all of us by the manufacturers, who disclaim any responsibility for damages done by the products they make.