In both cases, almost all of the long-term projected growth is from immigrants, mostly legal immigrants, and their descendants. In 30 years of looking, and hundreds of pages of manuscript writing, I have not arrived at the kind of dispositive conceptual breakthroughs about population growth that I think I have turned up for things like smog, congestion, political reforms, and Shakespeare authorship questions, certainly nothing to match Malthus' classical statement of the problem. But I have learned something. Human ingenuity has done amazing things to soften, qualify, and postpone the Malthusian pinch. But in the end, the craft of men, laws, and markets is no match for the laws of biology and physics.
Nothing can grow infinitely in a finite environment.
There are such things as natural limits, niches, and physical carrying capacities, and these natural physical limits impose human, moral limits and carrying capacities. You can't solve all the world's problems by importing them. Humanity is too big to get your arms around all of it at once. W.W. Norton, 1995. BioScience , June 1986, pp.