We all know that over long periods of time, land continents move, collide and separate, and oceans take on different shapes. Due to the rotation of the Earth, the positions and sizes and shapes of the continents have a significant effect on ocean currents.
In today’s world, the positions of the continents contribute to today’s ocean currents. There are five major rotational ocean currents on the globe today, known as gyres.
There have always been gyres, but only in today’s human dominated world, have the gyres also become garbage patches. Vast areas accumulating man-made marine flotsam.
The pollution in these areas consists mainly of floating chemical sludge, suspended plastic and other debris. Much of it can be seen from ocean-crossing boats, but for what we can see there is many times more of it that we cannot see. Some floats at the surface, and most floats below the surface at various depths.
There could be more than a hundred million tons of garbage in the North Pacific gyre alone. It does not all fall off ships. In fact, most cities in the world are situated on river systems, so a morsel of plastic thrown in the street in the Western USA or West of the Andes, or in Japan or Eastern Russia, can be carried by rain and streams and rivers and eventually take it’s place in the gyre in about five years.
Larger pieces are eaten by birds and fish and mammals. We find them in the stomachs of the dead. But as the plastic breaks down into smaller pieces, it works it’s way down the food chain. Even plankton, at the very base of the food chain, can ingest objects from the garbage patch.
So that plastic fork that we threw away in 1987 can show up as a trace amount of plastic inside a sausage on the end of today’s plastic fork.
If the plastic disintegrates entirely, it still exists in the form of toxic chemicals like PCBs and polystyrene. The seawater is no longer just water with dissolved minerals, it’s a suspension of man-made objects.
As we find more and more fish and birds with plastic in their stomachs, we also find that non-native species have invaded far and wide after being carried around the world attached to tiny plastic cruise liners.
Eventually we will need to find a way to take the pollution back out of the ocean and bury it deep on land, or we’ll all be poisoned and starving. But all that will take much longer than it took to add this stuff to the water in the first place, and it may even remain impossible forever.