OK, let's stipulate the climate change is happening. How bad will it be? Florida will not be underwater any time in the near future but we could see a sea level rise of 6 feet, major changes in precipitation patterns, increase in ocean heat content and more acidity--both of which might disrupt the food chain. And, under business as usual, it gets worse from there.
This seems pretty dire to me but you are correct, unilateral action by the US won't be enough.
But isn't this the beginning of the discussion? Or do we just throw up our hands and say it is hopeless and let's continue doing what we are doing regardless of the consequences.
What is the conservative solution?