Marine Litter Vital Graphics

COMPARTMENTS AND STOCKS

Howmuch plastic is estimated to be in the oceans and where it may be

Total plastic estimated to have ended up in the sea 1

86 million tonnes

50 000 tonnes/year Annual input from maritime activities* * Latest estimates available are from the 1970s

210 000 - 439 000 4 tonnes Floating on the open ocean surface

23 million tonnes 2 Coastal ocean waters

Plastic mass

= 100 000 tonnes

Floating plastic, just the tip of the iceberg

34 million tonnes Open ocean waters

29 million tonnes 3 Coastline and sea oor

Floating on the sea surface

0.5%

Coastal ocean waters

Open ocean waters

26.8%

39%

1 Calculated as 1.4% of all the plastics produced since the 1950s. From Jang et al., 2015 Notes: 2 Lebreton et al., 2012

Coastline and sea oor

33.7%

Sources: GRID-Arendal own calculations, each source is indicated in the notes 3 Assuming 66% of the plastic is buoyant. From Jambeck et al., 2015 4 From Cózar et al., 2014; Eriksen et al., 2014; van Sebille, 2015

Estimates of the open ocean surface stock of plastic debris have been steadily rising from 7,000–35,000 tonnes (Cózar et al., 2014) to 66,000 tonnes (Eriksen et al., 2014), and to 93,000–236,000 tonnes (van Sebille et al., 2015). The variation is mainly explained by differences in data standardization and methods used to scale up to global loads. Including floating particles larger than 200 mm, not considered in the figures above, would add a minimum of 203,000 additional tonnes to these estimates (Eriksen et al., 2014). Even using the highest of these figures, plastic debris represents only about 1 per cent of the 34 million tonnes of plastic waste estimated to be floating in the open ocean. Several explanations are put forward to account for the mismatch of about 99 per cent between the above generic calculation of the amounts of buoyant plastic in the open ocean and the amounts so far estimated through direct measurement, extrapolation and modelling (Cózar et al., 2014; Eriksen et al., 2014; van Sebille et al., 2015). This could be due to transfer mechanisms that are hard to measure, such as shoreline deposition, decreased buoyancy due to fouling, uptake by biota and excretion through sinking faecal pellets,

degradation, and high-energy oceanographic events leading to massive transportation from surface coastal areas to the deep open ocean. It has also been pointed out that the methods used so far to measure floating plastics do not capture the largest or the smallest items, thus leading to concentration underestimates. In summary, it is very important to note that while a lot of attention has been paid to the accumulation and potential impacts of plastics on the surface of the open seas, and solutions for its clean-up, this accounts for only about 1 per cent of the plastics estimated to have been released into the ocean. The other 99 per cent has received much less attention and, even if we improve the methods for determining the distribution of plastics in open ocean waters (i.e. at the surface or through the whole water column), these calculations indicate that less than 30 per cent of plastic debris “resides” in open ocean water. The remaining nearly 70 per cent – accumulated where sensitive ecosystems and many important economic activities are found – has been overlooked. The focus needs to be broadened to include risk assessment and clean-up operations in these areas.

Marine Litter Vital Graphics

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