where is the [yawn] smiley when you need one...
CO2 concentrations are lower the previous geological eras, but then humans haven't been around for even one geological era yet.
lets leave CO2 out of it shall we, and look at non-global warming issues
emmissions pollute, we have a number of areas in many towns where the atmosphere is at best unpleasant and at worst unhealthy, and if you happen to be one of the poor sods that live in these bits it affects your health. emmissions are getting lower per engine, but the number of engines around is going up. production (of anything) also uses energy.
cars in general, while being very convenient, are also a pain in the ass, especially in cities where facilities to park them take a lot of floorspace.
If (like me) you don't want nuclear power then we have to make scarce resources last longer, using less energy is a good way of doing this.
So to my way of thinking, global warming is only a tiny part of the equation anyway, as using less energy, and using it in ways that reduce emmissions, is a good idea. Reduced car use is a good idea, public transport in towns and cities is a good idea, reduce, reuse and recycle is a good idea, without global warming these things are still sensible.
Point taken on tax, but smokers pay a lot of tax, I belive far more than they cost in healthcare from the NHS, and it hasn't stopped the government hounding them to quit.