Population / environment linkages: discontinuities ahead.

A "growth of limits" is the emerging reality of population growth and natural resource depletion. Careful management of resources and radically curbing population growth provides greater leverage in managing the sheer numbers. An example is that if Nigeria achieves a 2-child family norm by 2010 then population size will be held at a projected 324 million but if not the population will rise to 622 million. If unmet needs of noncontracepting couples are met the global population will be 2.2 billion smaller. If there is expanded tree planting numerous benefits beyond supplying fuelwood and timber would be derived. Replanting efforts currently are only 20% of tree-cutting. Economic growth is not sustainable in its present form. The net grain output is <1%/year and population growth is 1.8% worldwide and 2.1% in developing countries. There is a multiple linkage between population growth and environmental degradation. Environmental discontinuity occurs when ecosystems are eventually pushed beyond their limits to regenerate or respond resiliently. Examples are the acid rain damage due to forest and freshwater degradation and the buildup of greenhouse gases. Unfortunately not enough is known about these environmental discontinuities in spite of their significance and assumed expansion. Examples are given of the consequences of shortages of land in the Philippines where the landless moved onto upcountry slopes and cut down forests and contributed to deforestation and soil erosion. Agrarian reform agricultural extension services rural credit systems marketing networks and sufficient rural investment have been lacking even though modes attempts have been made in policy to promote more efficient and equitable shares of farmlands. Agricultural shortages are common in developing countries. New technologies have not been able to keep pace with the growing numbers. A 50% increase in cultivated lands in developing countries is needed by 2025 when the present increase of 24% has been stable since 1981 because further degradation of land has occurred and there is little suitable land remaining. The expectation is increasing grain deficits rising grain prices and spreading hunger. Fuelwood stocks are also decreasing as well as chronic water shortages. 80% of developing country disease and 90% of child mortality are attributed to waterborn pathogens. Pest depredations of food crops may occur if the balance in nature is upset; this contributes to many synergistic interactions with an adverse impact on human sustainability.