Optimization isn't about focusing on the largest resource consumer, but on the most reducible. (Note that this makes your statement basically tautological) And

Optimization isn't about focusing on the largest resource consumer, but on the most reducible. (Note that this makes your statement basically tautological) And given that China's main problem is its population (which is basically impossible to reduce much more right now and they're still dealing with negative side-effects from their effective but not-very-nice One Child policy), not it's emissions per person, China doesn't have as much to reduce. Whereas if the US lived at China's level of emissions per capita, then the world's total greenhouse emissions would drop by over 10%.