I don't think there's cause to feel guilty about flying or other technology. The transition to an advanced industrial society, in a competitive and violent world, requires ruthless forward progress if you want to create and defend your prosperity and freedom. In the long run, improved technology will allow us to stop damaging the environment. The best way to get there is to move full speed ahead. Between nuclear power, electric cars, biofuels, and other renewables, we are almost there.