Sometimes it really is this simple:
In short, the choice for developing countries is between mass death due to the consequences of an overheated planet sometime in the distant future, and mass suicide due to imposed instant starvation right now. Is it any surprise that they are reluctant to jump on the global-warming bandwagon?
And of course, without these developing countries on the bandwagon, you know, the ones with well over half of the world's population, nothing anyone else can do will help. Except, of course, increase misery, slow economic growth, and ensure the only place where real job growth will occur is in the public sector.