How airlines can fly around new carbon rules

Aircraft are gradually becoming more fuel efficient, but that's not happening fast enough to keep up with the boom in flying

The world's airline industry adds to climate change. It burns the equivalent of more than 5m barrels of oil a day, adding up to around 2.5% of all carbon dioxide pollution, in addition to nitrogen oxides, soot and water vapour, which place an even bigger burden on the world's climate.

Aircraft are gradually becoming more fuel efficient, but that's not happening fast enough to keep up with the huge boom in flying - since the 1970s, global air traffic has doubled in size roughly every 15 years. Flying is still cheap and budget airlines make it even more attractive, partly thanks to an international agreement reached in 1944 that prohibits tax on aviation fuel for international flights.