|Reversing the Spiral - The Population, Agriculture, and Environment Nexus in Sub-Saharan Africa (WB, 1994, 320 p.)|
Sub-Saharan Africa lags behind other regions in its demographic transition. The total fertility rate (TFR)the total number of children the average woman has in a lifetimefor SSA as a whole has remained at about 6.5 for the past twenty-five years, while it has declined to about 4 in all developing countries taken together. As life expectancy in SubSaharan Africa has risen from an average of forty-three years in 1965 to fifty-one years at present, population growth has accelerated from an average of 2.7 percent per annum for 1965-1980 to about 3.0 percent per year at present. Recent surveys appear to signal, however, that several countriesnotably, Botswana, Kenya, and Zimbabweare at a critical demographic turning point. This study discusses the factors that have contributed to the beginning of the demographic transition in these countries.
Agricultural production in Sub-Saharan Africa increased at about 2.0 percent per annum between 1965 and 1980 and at about 1.8 percent annually during the 1980s (Table A-9). Average per capita food production has declined in many countries, per capita calorie consumption has stagnated at very low levels, and roughly 100 million people in Sub-Saharan Africa are food insecure. Food imports increased by about 185 percent between 1974 and 1990, food aid by 295 percent But the food gap (requirements minus production)filled by food imports, or by many people going with less then whet they needhas been widening The average African consumes only about 87 percent of the calories needed for a healthy and productive life (Table A-10). But as with population growth, a few African countries are doing much better, with agricultural growth rates in the 3.0 to 4.5 percent per annum range in recent years (Nigeria, Botswana, Kenya, Tanzania, Burkina Faso, and Benin). The policies of these countries help show the way forward.
Sub-Saharan Africa's forest cover, estimated at 679 million ha in 1980, has been diminishing at a rate of about 2.9 million ha per annum, and the rate of deforestation has been increasing (Table A-19). As much as half of SSA's farmland is affected by soil degradation and erosion, and up to 80 percent of its pasture and range areas show signs of degradation Degraded soils lose their fertility and water absorption and retention capacity, with adverse effects on vegetative growth. Deforestation has significant negative effects on local and regional rainfall and hydrological systems. The widespread destruction of vegetative cover has been a major factor in prolonging the period of below long-term average rainfall in the Sahel in the 1970s and 1980s. It also is a major cause of the rapid increase in the accumulation of carbon dioxide (CO2) and nitrous oxide (N2O), two greenhouse gases, in the atmosphere Massive biomass burning in Sub-Saharan Africa (savanna burning and slash-and-burn farming) contributes vest quantities of CO: and other trace gases to the global atmosphere. Acid deposition is higher in the Congo Basin and in Cd'Ivoire than in the Amazon or in the eastern United States and is largely caused by direct emissions from biomass burning and by subsequent photochemical reactions in the resulting smoke and gas plumes. Tropical forests are considerably more sensitive than temperate forests to foliar damage from acid rain. Soil fertility is reduced through progressive acidification. Acid deposition also poses a serious risk to amphibians and insects that have aquatic fife cycle stages; the risk extends further to plants that depend on such insects for pollination.
Unlike the situation of population growth and agriculture, there are few environmental success stories in Africa, although there remain large parts of Central Africa that are little touched In looking closely, however, places can be found, such as Machakos District in Kenya, where environmental improvements have occurred along with rapidly expanding population. Good agricultural and economic policy, and investment in social services and infrastructure, are found to be the critical ingredients to such success (English and others 1993; Tiffen and others 1994) These positive experiences form the empirical basis for an action program to overcome the downward spiral elsewhere, which is discussed below.