ah, but Leanan, (just be Lucifer's advocate) how much food, technology, etc., does the US produce relative to the rest of the world?
I don't think it matters.  If, say, Dr. Goodstein's worst-case scenario happens, and we tip the world climate into a state "incompatible with life," will anyone care what we did to produce those emissions?  Building nuclear missiles, growing food, driving SUVs, or mass barbecuing at tailgating parties - does it matter?