Rod,
For the first time in human history we face a serious dilemma. You are right there is no single incontrovertible fact (and there probably won't be for some people until some of the houses start falling into the Swan River) - there is no magic pointer saying this is it - the bit of evidence that can't be refuted. Nevertheless there is more than sufficient evidence in the geological record and the current trends and changes, for the consensus taken amongst the worlds experts about that it is happening.
What do you expect them to do - nothing - wait till the changes are irreversible? I actually think it is probably already too late and we will be seriously affected and the best we can hope for is a mitigation of the effects.
What most people do not realise is this is a HUGE problem. An individual (even an expert) simply can't learn about or decide about man made global in a lifetime. It is such a difficult problem that it has required a collective consensus amongst experts and we will have to decide at some point to put our hands in their decisions - just like we do with doctors (yes they are sometimes wrong). I am very familiar with how international level scientists operate, they are not sheep - they absolutely love proving each other wrong and do so at the drop of a hat. If half, or a quarter or even 1/10 of the worlds GW experts were still arguing about it i'd be slightly skeptical. I am never 100% convinced of anything but in this case I'm about 99% convinced.
Cheers