Five Trillion Plastic Pieces

The Modelling House provided expertise in data modelling and analysis during an international research effort aiming at giving a first global estimate of the quantity of plastic floating in the ocean. We co-authored a publication that received an important coverage worldwide. Our model predicted over 5 trillion plastic pieces in the world’s ocean. This figure is now regularly referenced in journal articles and international medias.

Abstract:
Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global abundance and weight of floating plastics have lacked data, particularly from the Southern Hemisphere and remote regions. Here we report an estimate of the total number of plastic particles and their weight floating in the world's oceans from 24 expeditions (2007–2013) across all five sub-tropical gyres, coastal Australia, Bay of Bengal and the Mediterranean Sea conducting surface net tows (N=680) and visual survey transects of large plastic debris (N=891). Using an oceanographic model of floating debris dispersal calibrated by our data, and correcting for wind-driven vertical mixing, we estimate a minimum of 5.25 trillion particles weighing 268,940 tons. When comparing between four size classes, two microplastic <4.75 mm and meso- and macroplastic >4.75 mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove <4.75 mm plastic particles from the ocean surface.

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The publication was supported by an interactive geo-spatial visualisation which details the outcomes of the analysis. The application has had over a 100,000 unique visitors since its launch in late 2014 and proved to be a powerful communication tool of scientific insights.