Nothing. Nada. Zilch. Null.
There was something similar recreated in a German rock festival recently.
The scientific explanation can be found here.
Now, if the whole Chinese population farted, would that prove an old email claiming that the power of such a feat would equal a small nuclear bomb?
If so, then China is not only a economic super power but their true strength would be in their people.
Be afraid, be very afraid....