Environmental degradation is one of the most threatening global challenges currently faced by humankind. Despite generally decreasing birth rates, the global population continues increasing in absolute terms, which is an unsustainable trajectory. Efficient solutions would require new ethical principles, in particular, that no population group obtains any advantages because of a faster growth. In countries with sufficient food and water resources, the birth rate may be higher than in regions where people are consuming desalinated water and foodstuff acquired through international aid. In the past, overpopulation has been reduced by wars, epidemics and starvation. Today, the possibility exists of applying humane, scientifically based methods, consciously choosing between birth rate restriction and mortality rise. Unlike preventable shortening of life expectancy, birth control is ethically neutral. International tensions are among reasons to boost childbearing. Hidden reproductive coercion committed by the state is a mechanism of birth rate elevation. The military needs young people. In conditions of durable peace and mutual trust, large projects could be introduced to improve the quality of life.