You must walk before you can run. An Oregon carbon tax could serve as a model to others, and help inch us toward international consensus. It's a coordination problem; signalling serves an important role.
Indeed. I love the symmetry of state/national legislation skepticism (pointless, all large jurisdictions need to coordinate) and consumer behavior skepticism (pointless, need to vote for legislators who will pass laws impacting all consumers). It's a dynamic problem; most likely any one individual jurisdiction's or person's particular decision isn't going to change global outcomes, but it's hard to see how to get on a better global path without lots of decisions aiming for that at every level.
A carbon tax would indeed have been great, but unfortunately what was proposed was cap-and-trade and a bunch of "green jobs" pork. Better than nothing, possibly, but even so as likely to affect the international consensus as a zero-emission Oregon to affect the global temperature.