Peter Madden asks, “What should greens do about air travel?” The problem is twofold. Planes are responsible for about 3 percent of carbon emissions. But thanks to NO2 emissions from planes, and the fact that water vapor emitted at or near stratospheric levels (where planes fly) acts as forcing and not just as feedback (as at ground level), the actual effect on climate is about triple that from CO2 — about 9 percent and rising.

Yes, yes, part of solution to all these problems is to tax environmental effects, and to stop massive subsidies of environmentally destructive things (like airports). But what technical means exist to respond to such signals? Is the world going to have become a bigger place again, with less travel?

Here are the technical means to replace air travel:

  • Trains: Trains can replace almost all air miles occurring over land, replacing fuel with renewable electricity and avoiding all stratospheric and near-stratospheric emissions for those miles.

    CyberTran, though mainly discussed as a commuter system, has a 150 mph version that can replace most short-haul flights.

    Faster trains, like Japan’s bullet trains and perhaps ultimately MagLev systems, cold replace longer flights. Such faster trains, unlike Cybertran, are not notably more energy efficient than planes. But they can run on renewable electricity, and don’t produce stratospheric emissions.

  • Communications to replace transportation: Videoconferencing, telecommuting, and other forms of electronic communication have already replaced a certain amount of flying in the business world. The technology to do this improves every year. Skype provides better video conferencing for free than you could have gotten for thousands of dollars seven years ago.
  • Concentrate flights: Schedule flights during daytime hours rather than at night, and during the summer rather than winter. While at first glance this may appear to be “free,” it is actually one of them most expensive solutions: take the same capital and amortize it over many fewer hours.

Another solution I’ve heard people suggest is using ships and boats more. While there is nothing wrong with this, it is not very practical for business trips, and for leisure substituting a different kind of travel — one where the journey is more important than the destination.

So what should greens do about air travel now? The same thing they should do about everything else: take political action to change the infrastructure of society. Yes, there are things you can do to cut your personal carbon profile. But ultimately we depend on society’s infrastructure, and we will only become a low-carbon society when that infrastructure is low-carbon.

In the meantime, I’d suggest fewer in-person national and international conferences about climate change, and more video conferencing (at a fraction of the cost).