Worst-case scenarios and betting over climate change

At least some casual skeptics have come around to a reasonable position based on this climate-change video. If you don't feel like watching it, the summary is that the worst case scenario resulting from inaction over climate change, if climate change proves to be true, is far worse than the worst case scenario resulting from taking action over climate change if climate change turns out to be a false theory. Therefore, we're better off taking action.

Whatever convinces people to be reasonable is fine with me. This argument's strength depends on the probabilities you assign to climate change being true or false (I'm disagreeing with Inel here on her claim that the probability of it being true is 100%, but I agree it's very high).

My guess would be that anyone who thinks climate change has at least a 20% chance of being true should find this argument at least partially convincing, and the greater likelihood you give it above 20%, the more it should be convincing.

Conversely, if someone thinks the probability of anthropogenic climate change is less than 20%, the argument wouldn't be convincing. But then, my bet offers should be very attractive, especially the ones about natural warming.

It's back to the usual situation in my opinion - a person should either support action to fight climate change, or the person should bet me.