Marine Atlas: Maximizing Benefits for Kiribati

THREATS

PLASTIC OCEAN: MICROPLASTICS CONCENTRATION Like the rest of the world’s oceans, Kiribati’s waters are overflowing with plastic. Only 5 per cent of plastics are recycled effectively and forecasts expect that by 2050 there will be more plastic than fish in the world’s ocean.

The world produces 300 million tons of plas- tic each year. About 2 per cent of it—around 8 million metric tons—ends up in the ocean. It is a staggering amount, yet only 1 per cent of this plastic is actually found on the surface of the ocean. Half of this 1 per cent becomes caught in large gyres (see map); the other half is more widely dispersed. The other 99 per cent (7.92 million metric tons) of plastics in the ocean worldwide are unac- counted for each year. Science has only just begun to unravel the riddle of where this unaccounted-for plastic ends up. At the turn of the millennium, scientists uncovered a previously unknown phenomenon: microplastic. Eighty per cent of plastic waste enters the ocean via rivers and the other 20 per cent is tossed over- board from ships (see graphic). A portion of the plastic waste is carried great distances by ocean currents and gathers in large trash vortices such as the Great Pacific Garbage Patch in the North Pacific Gyre. On this journey, which can take up to 10 years, large pieces of plastic are progressively eroded, broken down by sunlight and eaten by bac- teria, fragmenting into many smaller pieces. The result is microplastic—plastic particles that are smaller than 5 millimetres. Thus, the Great Pacific Garbage Patch is not the massive islands of trash that one might first imagine. Large bits of plastic are relatively rare, and one could actually swim through a gyre without noticing the microplastic that composes it. The remain- ing 99 per cent of the waste that begins its journey on the coasts never reaches gar- bage patches. It also breaks down into mi- croplastic and disperses through the ocean, before finally sinking into the depths. In fact, the plastic concentration on the ocean floor is 1,000 times greater than on the surface.

70°N

MICROPLASTICS CONCENTRATION grams / km 2

0 - 50 50 - 250 250 - 500 500 - 1,000

1,000 - 2,500 2,500 - 5,000 5,000 - 10,000 10,000 - 20,000

North Paci c Gyre

Exclusive Economic Zones (EEZ)

30°N

Surface Currents

Copyright © MACBIO Map produced by GRID-Arendal Sources : Becker et al, 2009; Claus et al, 2016; Van Sebille et al, 2015; Smith and Sandwell, 1997.

10°S

South Paci c Gyre

50°S

140°E

180°

140°W

100°W

THREATS MAXIMIZING BENEFITS FOR KIRIBATI

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