Overpopulation was an early concern and interest. In a 1969 article, Holdren and co-author Paul R. Ehrlich argued, "if the population control measures are not initiated immediately, and effectively, all the technology man can bring to bear will not fend off the misery to come." In 1973, Holdren encouraged a decline in fertility to well below replacement in the United States, because "210 million now is too many and 280 million in 2040 is likely to be much too many." In 1977, Paul R. Ehrlich, Anne H. Ehrlich, and Holdren co-authored the textbook Ecoscience: Population, Resources, Environment; they discussed the possible role of a wide variety of means to address overpopulation. These included some extreme measures, none of which Ehrlichs and Holdren advocated, such as forced sterilization, compulsory abortion, contraceptives in the food and water supply, reproductive licenses, and more.
Other early publications include Energy (1971), Human Ecology (1973), Energy in Transition (1980), Earth and the Human Future (1986), Strategic Defenses and the Future of the Arms Race (1987), Building Global Security Through Cooperation (1990), and Conversion of Military R&D (1998).'
Ask yourself at what point do we stop, or does the United States keep growing its population forever? Do we stop at 500 million, or do we keep going to a billion