The problem would be solved if everyone acted responsibly, right? Companies strived to produce more efficient cars, people drove less and bought locally produced stuff, etc.
What you're saying here is that people aren't adequately policing themselves to abide by an ethic you believe is right and necessary. So the government should do it for them. Hmmm, sounds like the same reasoning that would enrage you, were the subject abortion, gay marriage, etc.
I know rationing is ridiculous, but I don't believe tax is the solution either. Yes, of course, it is A solution, and it will work, but the poor are hit the hardest while the rich never skip a beat and continue to drive their hummers. Looking at the whole picture, we need a different solution, one that adequately controls emission without putting an undue burden on those least able to bear it.
Come on, people, be liberals and care about the poor AND the environment. I know you can find a way... right?