Ocean-sieving expedition reveals huge amounts of microplastic in the Atlantic

A vast ocean-sieving expedition across the Atlantic has revealed that there is as much as 21 million tonnes of plastic particles suspended in just the top 200m of the ocean.

The findings, based on an analysis of samples and on computer modelling, highlight the largely invisible scale of the pollution clogging the world's second largest ocean, as BBC science correspondent Victoria Gill explains.

Video by Justin Oliver and Dianne King