FOOD SECURITY, POPULATION, AND ENVIRONMENT

Keeping global food production abreast of human population growth involves balancing the costs of inadequate diets against those associated with exceeding the limits of sustainable agriculture. Those limits are set by: losses of farmland to other uses; diminishing opportunities for irrigation; erosion and degradation of soils; biological limits to yield increases; diminishing returns from fertilizer use; chemical pest-control problems; declining genetic diversity of crops and their wild relatives; depressed yields from increased ultraviolet-B radiation and pollutants; possible rapid climate change and sea-level rise; and a general deterioration of the free services supplied to agriculture by natural ecosystems. Dramatic declines in human fertility, ecologically sustainable agriculture, preservation of biodiversity, and revised socioeconomic policies are essential to preventing further reductions of Earth's long-term carrying capacity.