It doesn't, it also doesn't account for the fact that China has a larger population.
The US only has about ~23% of China's population to sustain. GDP/CO2 is a silly metric to compare (No Patrick, selling financial products to increase GDP/CO2 isn't green).
In reality China is just "greener" (in CO2 emission) than the USA if you measure more reasonable metrics like CO2 emission per capita.
In reality China is just "greener" (in CO2 emission) than the USA if you measure more reasonable metrics like CO2 emission per capita.