Hmmm OK so 9 Billion people will over populate the Earth?
I have a question for you. How many states (of the USA) would 9 Billion cover if we all got together for one of those aerial group shots? (shoulder to Shoulder back to front like in a group photo)
Just because you can physically fit 9 billion people in the State of Texas doesn't mean that they would live for long in such conditions.
So do you think illegal immigration is an economic boon to the USA because of the extra population it provides?
If not, why not?
9 billion people may well live comfortably and happily upon the Earth, with better utilization of resources - that may or may not be the point of “overpopulation” that leads to demographic contraction due to epidemic or starvation or warfare or whatever the ‘release valve’ of the overpopulation ends up being.
The Earth, with better technology, may well support 14 billion people in health and comfort.
And it looks like we had better start planing for such, because despite the idiotic ramblings of a not very bright religious devotee, the Earth's population is increasing and AT an increasing rate.