The advantage that climate realists have over climate nihilists is that all we need to do is defense, and stop Republicans from passing legislation that amends the Clean Air Act. People look at the summer's 53-47 defeat of Sen. Murkowski's attempt to do just that as good news, saying Republicans need a majority in the House, 60 votes to overcome a filibuster, and possibly override a presidential veto by two-thirds vote in both houses.
I don't think defense is that easy. Republicans will focus on the budget process and attempt to amend the budget so that the EPA can spend no money to enforce or promulgate regulations related to climate change. As a budget item, it's not subject to a filibuster (UPDATE: should've said, as a budget reconciliation item, it wouldn't be subject to a filibuster, but that only makes it a slightly harder hurdle to overcome). Right now, the attempt would likely fail in the Senate by a 53-47 vote against, but if the Republicans pick up four or more Senate votes as predicted, then they've got the votes.
The Senate might then be in a game of chicken with the House, or maybe not if the House also switches enough votes to the Dark Side on climate budgeting. Obama could theoretically veto a budget with this provision, but in an election year budget with money for seniors and soldiers, that'll be hard to do. I could see an unfortunate compromise as a result.
Conclusion #1: we're in a hard battle yet.
Conclusion #2: this might have something to do with Obama's disappointing opposition to climate change lawsuits. He's saying that they should be dismissed, as long as regulations are in place and enforced. Having a stick of lawsuits waiting in the wings if the Republican zero out the budget might reduce some enthusiasm for that budgetary trick.
Anyway, the budget is what we have to watch.