If you read the article carefully and checked the references you would know where the 12 acres came from. Incidentally the author used 10 acres to calculate the 70 mil overpopulation. If you dont think many of our large cities are overpopulated, I doubt that youve been to one lately.
Can you think of any problem, in any area of human endeavor, on any scale, from microscopic to global, whose long-term solution is in any demonstrable way aided, assisted, or advanced by further increases in population, locally, nationally, or globally?
Words of wisdom from Albert A. Bartlett an emeritus Professor of Physics at the University of Colorado at Boulder.
That's what makes it a "city" -- lots of people.