You can now fly from London to Dublin for less than the price of a taxi from the airport to the city. Flights are cheap because the atmosphere is a global commons, free for all of us to use. This cost will be borne by all of us, especially in areas vulnerable to storm damage, drought or rising sea-level. Flights are cheap because aircraft fuel, unlike fuel for all land-based transport, is not taxed at all.
Flights are cheap because oil is cheap, regardless of environmental impact.
It took millions of years for tiny creatures in the sea to capture sunlight energy and CO 2 and store the carbon in oil reserves, yet since we pay only for the cost of extracting fossil fuel, we squander this limited resource recklessly. However the reserves are now dwindling and it seems that a large increase in the price of oil is imminent. People's labour is taxed heavily through income tax. If we increased fuel taxes, we could decrease labour taxes and train tickets could become cheaper. Flights are cheap because airports and airlines are a prestige symbol -both to national and city governments around the world, and are therefore heavily subsidised.