“Pushing Against a Ceiling”

● In discussing the earth’s population, Nathan Keyfitz, Professor of Demography, pointed out that a doubling of earth’s population took place between 1825 and 1927, or in 102 years. The evidence is that a second doubling, from 2 to 4 billion (thousand million) will occur by 1975, or in just a space of forty-eight years. However, the professor points out that the rate of increase is rising, and so the time required might even be less. Then he adds: “On the most optimistic assertions about the number of people that can live on the earth​—however uncomfortably—​only two or three doublings more are possible. Under the best of circumstances we are pushing against a ceiling that will be reached within the lifetimes of children already born.”​—Environment—​Resources, Pollution & Society (1971), page 32.