THE oceans are awash with plastic. It is most visible in the huge rotating ocean currents, or gyres, such as the “Great Pacific Garbage Patch" off the coast of California where tonnes of debris float in an area the size of Texas. But though there have been studies on how much there is and where it is distributed, until now there have been none on where it is coming from.

A new paper by Jenna Jambeck of the University of Georgia, published in Science, is the first attempt at doing so. Dr Jambeck and her team used World Bank data on municipal waste generated in 2010, the population of every country that lives within 50km of the coast and income levels to estimate the amount of plastic generated in every country that could be washed into the sea. Out of 275m tonnes of plastic waste generated in 2010, the researchers conclude that between 4.8m and 12.7m tonnes entered the ocean. This is a lot: 4.8m tonnes is roughly the same as the entire global tuna catch.

The countries with the highest mass of mismanaged waste are those with rapid growth but little in the way of formal waste management systems as well as large coastal populations; 12 of the 20 biggest are in Asia. China is responsible for almost 9m tonnes, or 28% of the total volume of waste plastic. Around 1.3-3.5m of this makes its way to the sea. America ranks 20th, despite having adequate waste management, because it has a very high rate of waste generation and so inevitably some of it ends up as litter in the ocean. If current rates of economic growth were to continue, by 2025 the cumulative total dumped in the sea could reach 155m tonnes.