Copenhagen and Collective Action

Let me leave aside for the moment all the leaked memos and stuff.  I have a question about Copenhagen that predates all of that.  I’m not being snarky – taking on assumption all the climate problems as they have been stated, I do not understand how this exercise manages to overcome the collective action failure problems that have been encountered in Kyoto and every other exercise in this area.  Extremely diffuse damage from a multitude of players, now and into the future; diffuse set of actors who must act in a coordinated way; individual states being tasked to take sacrificial actions that in the short and medium term at least are bad for their individual economies and their voting citizens; consistent record of failures not just in the nature of the promises made, but in their non-fulfillment even as they stand … on what grounds does anyone plausibly think that Copenhagen might produce a different outcome?

I’m not asking about climate science here, I’m asking about collective action problems in international law and policy.  How is this exercise different from previous failures?  Even if new states are persuaded to say yes on paper, on what grounds does anyone think that these commitments will be fulfilled this time, particularly given the record of Kyoto?  The article linked here from the AP talks about “momentum building” and “legally binding agreements.” What does that mean and how?  Legally binding to prevent defection down the road, how?  This is not an attempt to get snarky, but complete puzzlement on my part.  How is this different from earlier attempts?

The one thing that might be different, so far as I can tell, is that the meeting might make moves toward the global fund for the developing world.  Which would suggest, however, that the world has largely accepted that it won’t really do anything about the problem on the front end, but might do things to address concrete damage in the developing world.  Or perhaps will simply hand out the money as a sort of buy-off and global welfare transfer payment.  That seems to me to be the most likely outcome of Copenhagen, at most, and maybe or maybe not an agreement that, on the basis of past experience, will be invoked in op-ed pages and law review articles and politely sidelined as discussions get underway for the next round of agreements.

But there are lots of very smart people working on this issue in international law who, obviously, have thought long and hard about these problems.  How are the collective action problems believed to be overcome in this round?

(Update: And one of those very smart people responds!  Noah Sachs puts up a note responding to the VC version, over at Prawfsblawg.  Thanks Noah!)