This is meant to be a thought provoking question, not an attack:
What if the safety of the planet lay in stopping greenhouse emissions. But certain large blocs of the international community refused to stop pumping it out of the ground.
Now say diplomatic means don't create any real progress, only broken promises. For an example of what that might look like, take the nuclear accord John Kerry just got Iran to sign this year. Already they have tested new long range missiles and their leader, Khamenei, released a statement this week: "Those who say the future is in negotiations, not in missiles, are either ignorant or traitors," [0].
Seriously, what happens when those with fossil fuel reserved chose to use them, even when your country is being responsible? What if it meant another war in Iraq: would the positions on policy for fixing AGW swtich between Democrats and Republicans?
it is an interesting question - would we go to war to prevent carbon release?
for me to have a position on the question would depend on the particulars.
A related thought - there aren't a ton of countries that have both large fossil fuel reserves and a large enough domestic market to burn them at a high rate. US and China are the only two that come to mind. Maybe Iran? Which implies that sanctions (either on the import of energy or the export of finished goods) might be effective if you can keep the US and China on board.
Phase three will be "it was actually the liberals who blocked action on climate change"