Spread floating debris evenly over the whole ocean and let the surface currents carry it. Where does it end up? We followed 60,000 floating particles for ten years with the surface currents of a global ocean model. Within a year the particles start to gather in five places: the centres of the five great subtropical gyres, the slowly turning loops of current in the North and South Pacific, the North and South Atlantic and the Indian Ocean. The wind pushes surface water towards the middle of each gyre, and floating material collects there and stays. After ten years most of the particles sit in these five patches. The North Pacific holds the most, in an eastern patch between Hawaii and California, known as the Great Pacific Garbage Patch, and a western patch east of Japan. The real garbage patches are not islands of rubbish. They are huge areas where small pieces of plastic float at much higher concentrations than elsewhere, many of them too small to see from a ship. This is a simple model: passive particles moved by the monthly average surface currents, with some random spreading. Particles that reach a coast stay there.
Source: Currents: E.U. Copernicus Marine Service, global ocean reanalysis (GLOBAL_MULTIYEAR_PHY_001_030), monthly climatology of surface currents, used at 0.5°. Drift model: The Moving Sea. Visualisation by The Moving Sea
Free for personal and educational use with credit to The Moving Sea. For commercial use, contact [email protected].