Most people agree on basic values. It's really not that big a stretch to appeal to such common values, seeing as rapid global warming would cause mass relocation, suffering, adaptation costs for those who can stay put, etc.
> Most people agree on basic values
This isn't even true at a local level, let alone at the global scale.
Considering how current world powers are heavily increasing military spending as well as the heavy rightward shift in many governments, I'm no longer convinced we'll do the right thing. It feels more and more like poor countries will be left to fend for themselves, so the "developed world" can plunder the remains to prop ourselves up just a bit longer.