The United Nations Department of Economic and Social Affairs Population Division in its recently published 2015 Revision of World Population Prospects indicates that global population size is expected to exceed 11 billion by 2100. This projection should not be considered in isolation. In the Revision, the Population Division provides some important — and surprising — contextual information.
The projections for fertility rates during the next 85 years in particular are worth considering because they hint at the true complexity of the population issue. Rather than increasing along with population size, global fertility is expected to decrease from the current rate of approximately 2.5 children per woman to about 2.0 by 2100. Even the least developed countries are expected to experience a significant reduction — from an average rate of 4.3 to 2.1.
That global population is expected to increase despite the predicted fertility rate decrease seems at first to be rather confusing, but some of the Population Divison’s other projections provide clarity. Between 2015 and 2100, global average life expectancy is predicted to increase from approximately 70 years to about 83. The average African is predicted to gain 19 years of life expectancy by the end of the century and Europeans are expected to gain 10 years. These developments, which in part will result from continuing, rapid declines in infant mortality rates across the globe, will counteract the reduction in world population growth that reduced fertility rates would otherwise produce.
An anticipated long-term increase in the global number of women of childbearing age — from approximately 1.6 billion in 2000 to about 2.3 billion in 2100 — holds its own implications for future birth rates. Despite decreasing fertility the total number of births is likely to increase. This is an especially pertinent issue given that fertility rates are difficult to predict and may very well not in fact decrease per the forecasts. Future fertility rates in Africa especially are a subject of “significant uncertainty”, according to the Population Divison, and “slower-than-projected fertility declines would result in much higher population totals in all subsequent time periods.” The impact of this outcome on the availability of natural resources, which we are currently consuming at a rate that is approximately 40 per cent faster than the one at which Earth produces them, would be catastrophic — particularly in poorer nations.
The necessity of reducing fertility rates is obvious, but United Nations estimates indicate that about 22 per cent of the women in the world have an “unmet need for family planning” — meaning that modern contraception or the freedom to use it is not available to them. The proliferation of such contraception therefore should be of the highest priority.