This little gem turned up in the news today. The suggestion that the rest of industry should cut greenhouse emissions even more to accommodate the growth in aviation is frankly silly. Aviation has to do it's part and certainly in the short-term this means less flying. In this context it's hard to see what building extra runways will achieve in the next 10 years.
Charlie Stross recently posted his analysis of what he could do to reduce his foot print. He was disappointed to realise that any effort he made locally was literally blown out of the water by air travel. Turning to my favourite climate change numbers reference I can see even the fullest most efficient plane works at around 37 kWh per 100 p-km, twice as efficient as me driving in my car on my own. So the lesson is rather simple physics, transporting mass from one end of the globe to another requires energy and that means its unsustainable at it's current growth rate. There is a lovely appendix at the back that examines the physics of air travel in more detail. The final conclusion is that although there may be scope for some improved efficiency in planes they are already getting close to what the physics will allow.
If we are going to travel to far away climes we need to start getting used to the idea of taking longer about it. We will also need a set of intercontinental underwater tunnels for those electric trains which are about the only way you'll get the efficiencies (6kw per 100 p-km) to make up for all those extra miles.