China's 10% GDP isn't free. It is costing tens of millions of lives in the form of cancer from smog and other pollutants. Worse, the people in Japan have to suffer breathing someone else pollution:
Cuba is vastly poorer than China and maintains an approximate death rate to China while maintaining approximately equal birth rates and almost identical GDP per capita, with a vastly lower unemployment rate:
Just like the market, the environment will balance itself out. Those that kill nature, kill themselves. When enough people die that its noticeable to all, they'll change. Until then, they wont.
Unsure true or not. Probably some major cities in the world historically also had very similar environmentally unfriendly problems (perhaps not as bad) during their industrialisation development process.