Thermo nuclear war. Lets see... With TNW, you can kill off the main population; the malthusianist would be happy. Nuclear winter would ostensibly counter AGW. And, well, conquest of warfare. But most of all, the Earth will be saved.
Feeling confident yet?
The beauty of this global warming is that if you want to save the planet, you don't have to do anything at all. Even if there's a runaway process for a while, it'll just be yet another extinction event. And one of those is going on anyhow (Holocene extinction) so won't make much of a difference. Long term it's really not something that'll kill of all life on earth.
Global warming is mostly a human / political problem, as relocating that many people to higher ground, reorganizing food production and such are simply not feasible with our current politics. Well, at least until temperature shoots up by 20 degrees or so, but by then WW3 will have been played out anyhow.