Sea of green

To most people, shipping is the green face of freight transport. While the low-carbon arguments focus on speedy but fuel-hungry, CO2-spewing aircraft, the fleets of container ships and tankers give the impression of patience, slowness and a gentler, low-impact way of moving goods around the world.

Of course, this is not the whole story. While it is true that marine diesel engines are more efficient than jet engines, the actual emissions from shipping are more than twice as high as those from aviation, and they are increasing fast. As much as two years ago, a joint study from BP, which owns a 50-tanker fleet, and the German Institute for Physics and Atmosphere showed that annual emissions from shipping were ranging from 600 million to 800 million tonnes of CO2, around three per cent of the world total, and that they were on track to increase by around 75 per cent in the next 15-20 years. According to the International Maritime Organisation (IMO), annual emissions have now topped a billion tonnes of CO2 and could double or triple by 2050.