Cargo ships are the world's worst polluters, so how can they be made to go green?
Shipping produces more carbon emissions than most countries and pollutes the oceans. Will slowing vessels or making them electric do enough? Mark Piesing reports
Every day the clothes, tech and toys that fill the shelves in our shopping centres seem to arrive there by magic. In fact, about nine out of 10 items are shipped halfway around the world on board some of the biggest and dirtiest machines on the planet.
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