Global Plastic Waste Input into the Ocean between 1990-2015

Marine plastic pollution has been recognized as a serious issue of global concern with substantial risks for marine ecosystems, fisheries, and food supply to people. Small plastic particles are found everywhere in the ocean, from floating in large subtropical gyres to polar regions, frozen in Arctic sea ice and accumulating on the sea floor. Yet, the amount of plastic entering the ocean from land and rivers is barely known. Currently, estimates exist for the coastal plastic input in the year 2010 on country-level resolution and for riverine plastic input for the year 2017. Key limitations are the restricted data availability on plastic waste production and it’s fate. In addition, the transport of mismanaged plastic via wind and rivers is currently not well understood.

We present a model to estimate the global plastic input to the ocean for the years 1990-2015 on a 0.1x0.1° raster. To this end, we first train two independent machine learning models (neural networks and random forests) and a linear mixed model to predict plastic waste production on country level, using data of municipal waste collection and several socio-economic predictor variables. We then estimate the amount of plastic waste that enters the environment, using high resolution population data and waste management data of each country. This is combined with distance-based probabilities of land and river transport to obtain the annual amount of plastic entering the ocean on a 0.1x0.1° spatial resolution. Several scenarios with different waste management practices were created and a sensitivity analysis on several parameters from the waste production models is performed to identify factors with a high influence on marine plastic input.

Our results indicate that global plastic waste production increased linearly between 1990 to 2015. However, estimating the amount of mismanaged waste and the subsequent transport towards the ocean is afflicted with high uncertainties.