A Prediction of Marine Plastic Debris Growth

Although it is common knowledge that plastic waste finds its way to the ocean en masse as evidenced  regions of high marine debris such as the great Pacific Plastic Gyres, there are few statistics that put exactly how much plastic enters the oceans into frame. A study published in February of this year looked to do exactly that, estimating that in 2010 an approximate 4.8-12.7 million metric tons of plastic entered waterways over 192 coastal countries that year.

This estimate was generated by taking into account local statistics for waste generation per capita and population growth trends to predict the amount of trash that shoreline countries produced within a 50 km region from the coast. An approximation of 11% plastics content for the produced waste was then applied, and transformations were imposed to convert total plastic waste to mismanaged plastic waste and finally to marine plastic debris. The authors of the study state that their estimate is one to three magnitudes higher than estimates made based upon gyre plastic content and justify this by reasoning these other estimates to only account for buoyant plastics. However, this large discrepancy between the predicted value and others brings the accuracy of the estimation into question. In the materials and methods section, the described transformation from mismanaged waste to marine waste was arbitrarily set at a percentage set of 15%, 25% and 40%, values that were deemed conservative based on a described estimation for the San Francisco Bay area.

Fig. 1: Projected plastic marine debris entering the ocean from 2010 on (Article in Discussion)

The study also estimated based on the same model that a cumulative 100-250 million metric tons of plastic waste would enter the ocean by the year 2025. This range was based on an extrapolation of population growth and plastic waste content growth rates in the past, and for this reason may be brought under scrutiny considering emerging efforts to stifle plastic waste pollution. However, the numbers produced in this study still has shock value, which lends them importance. Knowing that these enormous numbers are estimated based on current and past trends should in itself be a wake-up call since the implication is that our current lifestyle is unsustainable and resonates into the foreseeable future. In other words, this study is a call to action for all countries to set measures in place that will curb marine pollution currently and protect our future oceans.

The study goes into further detail about the extent to which efforts to reduce plastic waste in the near future will affect the amount of plastic trash that ends up in the world oceans and also gives a more detailed breakdown of the contributions of each country to marine plastic debris. It is definitely worth checking out and can be found in full text here. Thanks!