Top image: "Chi-Town" by Stefan Morell.
Perpetual population growth on a finite planet?
Overpopulation and sustainability are problems not so much for the future as they’re problems for the present. We’re not able to deal with these things now — so we’ve projected our current inability to cope onto future generations. Indeed, there are 870 million people living today who are chronically undernourished. And as the biologist E. O. Wilson has said, we would need four planet Earths to bring everybody up to first world standards. And then there's global warming to consider.
A world transformed
How are we going to feed everybody?
For example, the researcher Eric K. Drexler has already developed extensive theoretical arguments for the feasibility of nanotechnology, a bottom-up manufacturing technology which will allow the synthesis of cheap food and housing from raw materials for extremely low costs. This technology could also be applied towards the construction of cheap spacecraft or space elevators, giving millions or billions of individuals the opportunity to colonize the solar system should the Earth become uncomfortably overpopulated. Marshall T. Savage has estimated in his book "The Millennial Project" that the Solar System could sustain upwards of a billion humans, each with mansions upon mansions of living space, for several billion years. This book also neglects the more recently-conceived benefits that advanced nanotechnology and virtual reality would confer once they mature.