Commute across Europe?

This article on the BBC News website is quite interesting; I have thought about doing this, but I'm not sure if it'll work or if I could do it ethically. I don't think it would work with my current job, but it's a thought if you're wondering what living abroad might do for you. If you read the comments to the article you see an argument forming like this:

For - I commute from country A to country B, I manage to spend more time at home with my family, commute less time each week and have a higher standard of living/higher disposable income. I know that there is an environmental cost, but surely the plane would be flying that route anyway so the total pollution for the flight remains the same, but we've one less car on the road every day.

Against - How irresponsible you are? Aviation is the most polluting of all travel, this world is dying and we all need to stop pollution and our contribution to the climate change. Whilst I can understand living abroad trying to work in one country and work in another is untenable, make a choice between one or the other.

It's interesting and I'm not sure where I stand. The thought of living somewhere else with the same money is very appealing, thus becoming effectively richer is great, especially when you think of that comparison in the article on air prices and train fares. As always the "good" guys' arguments sound weak compared to the "bad" guys. For example, the commuters are all about look what I can do, look what I've got, this is so much better - very me oriented and you can see the appeal. The environmentalists are quite simple in their statement - air travel is bad think of the environment. What we see is lots of fors and one against (two if you include the tax argument or sundry costs argument). I think the environmental argument is one massive argument compared to the lots of small, but people are very selfish and don't think like that.

As an exercise in proving who is right from the environmental point of view I'd like to know how the environmental costs compare. Firstly on a per person basis by comparing environmental footprint of just one week or one month's commuting (car travel daily versus two plane trips weekly, that sort of thing). Secondly work out what would happen if we all did it. I reckon the plane would be worse than the car immediately, but if not and it was practical environmentally for certain journies I think that if everyone did it, it would be completely unacceptable. I mean, if I flew from Barcelona to work compared to my 9 mile drive that is nuts and so the average would make this impossible to do without serious environmental, infrastructural and social damage.