I'm pretty pessimistic wrt GW but you never know, somebody might appear on the political scene like a Nixon (Clean Air/Water act, EPA) that accidentally makes a difference while pursuing their own political self interest. Or perhaps a "stealth" move like Obama's ban on coal fired generation that he didn't really highlight in the campaign but implements after (although it looks like he whimped out in the end?).
I guess the most radical thing that might happen is a coalition might appear that is agnostic to the unsolvable social issues like abortion, guns, drugs (which was the initial position of the TEAs and OWS and even O to some extent) but strong on other issues, say; structural inequality, civil liberties, and accidentally (because they aren't foaming at the mouth over people's sex habits) reducing GHG.
Although one of the most effective actions taken to forestall both PO and GW must be the new CAFE standards - yeah I know, it was Obama's deal and the radio says if he did it it must be bad. But they will do more to reduce GHG that PO will through higher prices and [url]=http://www.newgeography.com/content/003061-obama-fuel-economy-rules-trump-smart-growthother pressures to reduce driving[/url]:

The beast is our instinct to find an easier way, it's why we decided to plant seeds and store the grain instead of wandering around looking for it and to domesticate animals instead of chasing after them all over the place. Left to our own individual instincts we aren't going to do squat to reduce because a) we have to think about it first and B) to do so means things get harder and that is just not our way. Americans especially have gotten the idea that the individual is paramount, primarily because we are born on third base (a virgin continent just a few hundred years ago where old timber and oil and gold nuggets were just lying around for the taking) and consequently we think we hit a triple - "we built that" really is our national delusion.
We've co-opted the third world as a sweatshop because there is no protection there for labor or the environment and we don't make the connection and say "tsk, tsk" when we read on our iPhones that some little girl jumped off the roof of an Apple factory/internment camp in China.
So I don't know, I guess my opinion is the only way is going to be the socialist/representative democracy path (rather than the direct democracy idea put forth in the OP) because sufficient numbers won't directly vote for a harder way and for curtailing comfort in any fashion. An unpopular and/or self-serving decision made by the executive that his own party hates and rails against but that either serves that politicians' own personal goals like Nixon's EPA, or a stealth move like O's failed EPA action against coal which I don't remember him campaigning on to a large extent (although Romney and all the conservatives did and still do, LOL).
The legitimate object of government, is to do for a community of people, whatever they need to have done, but can not do, at all, or can not, so well do, for themselves -- in their separate, and individual capacities.
-- Abraham Lincoln, Fragment on Government (July 1, 1854)