Discouraging of air traffic, for example, by imposing higher taxes on aeroplane fuel.
250 million travellers use international scheduled services a year -- equivalent to one in every five of the world's population. In 1994 it was estimated that the income elasticity of air traffic in West European countries is 2.4, which means that a 1% increase in income leads to an increase of 2.4% in air traffic. As a consequence, air traffic is currently growing at an annual rate of 5% and is expected to double every 14 years. Much of this is in the tourism sector which is offering cheap air travel holidays.