It should start with better rubbish collection on land

PLASTIC DEBRIS IN the ocean has surfaced recently as a prominent environmental concern. Other pollution takes a greater toll on the seas—fertiliser run-off can cause damage worth $200bn-800bn a year, compared with $13bn for marine plastic litter, according to one estimate. Yet palpable, garish plastics nevertheless attract the most attention. Rich-world television audiences gasp at harrowing images of sea creatures ensnared in disposable bags. Citizens of poor but pretty places worry that rubbish washed up on once-pristine beaches puts off wealthy sun-seekers.

The best solution is better rubbish collection in Asia. Just ten countries, eight of them Asian, spew two-thirds of all marine plastic litter originating on land (ships shed some, too, particularly old nets). Fully 90% of the stuff discharged by waterways comes from ten rivers, two in Africa and the rest in Asia. Around 1.5m tonnes of plastic flows down the Yangzi river in China each year, compared with 18 tonnes from the Thames. Scooping all this up will be hard.