Even if humans make a transition to renewable energy sources, stop polluting and degrading their environment and accept a standard of living equal to one-half of that enjoyed by Americans today, the numbers stay the same. Getting there will be painful, Pimentel admits, but achievable. Population reduction will require a growing proportion of elderly to be supported by a shrinking number of younger, more productive humans. But our alternative is far worse economic and social stress. If global human fertility can be reduced from the current rate of 3.3 children per female to 1 to 1.5 children per female, Pimentel estimates that the population can be reduced to carrying capacity in 100 to 150 years.
Population control presents ethical problems.
People say that they should have the freedom to reproduce. I'm sympathetic to that view. But you're going to either lose some of that freedom, or your children and your grandchildren will lose some of their freedoms-freedom from starvation, freedom from disease. Look at fishery production. We built bigger ships, larger nets, and now the fish populations of the oceans lakes and rivers are lower than they've been since 1970.