Ships get older and slower as emissions rules bite

If shipping is the beating heart of global trade, its pulse is about to get slower. Faced with uncertainty about which fuels to use in the long term to cut greenhouse gas emissions, many shipping firms are sticking with ageing fleets, but older vessels may soon have to start sailing slower to comply with new environmental rules. From next year, the International Maritime Organization (IMO) requires all ships to calculate their annual carbon intensity based on a vessel's emissions for the cargo it carries - and show that it is progressively coming down.