you suggest we 'do something' based on inconclusive evidence? 'do something' despite not knowing if something should be done? how about wethern's law
I don't think the evidence is "inconclusive". I think it's pretty solid. We'll never know absolutely for sure, even 1000 years from now. You can never know anything like this for certain. It's not something amenable to experiment.
Optimisation dictates we take the path that is sure not to be bad, instead of the one that MAY not be bad.
I agree. You don't sit around until you're sure (oh look, the ice caps melted and we're all dead. Guess GW was true!). The most rational course of action is to start trying to improve things in a reasonable manner. I'm not advocating that we shoot all oil and coal company executives. I support alternative energy research
and implementation (the latter has so far been
severely lacking in the US), including nuclear, wind, geothermal, solar, "clean coal", etc.
I also do believe that many people are trying to take advantage of this "panic" to make a buck. Unfortunately this includes a lot of people trumping up the use of bio-ethanol derived from corn. I do think that some biofuels might pay off, but corn-derived bioethanol is not one of them, unless some miraculous leap in efficiency is uncovered (and I don't think that's likely). We should be putting money towards things that have a good chance of working, not things that have the biggest lobbying groups.
I also see a lot of just flat out unreasonable objections to this kind of stuff, like "wind farms are ugly". WTF? Ninja, please.
So no, I don't think we really need any more evidence to "prove" global warming. We have enough that we should start acting now (though doing more research certainly won't hurt, so we understand all the factors involved better).