Life expectancy is up and poverty is down worldwide, even with our rapidly expanding global population. Are our fears of catastrophe overblown?

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Last year, the world population reached 7 billion. It added the last billion in merely 12 years, similar to the time it took to add the fifth and sixth billion. Despite this rapid growth, the doomsday predictions of previous decades about the potentially disastrous consequences of rapid population growth have not materialized. Indeed, during the recent decades of rapid global population growth, various summary measures of individual well-being have in fact increased: For example, from 1960 to 2010, global life expectancy increased from 51.2 to 67.9 years, infant and maternal death rates declined substantially, education—and, importantly, also levels of female schooling—increased, global per capita food production and consumption rose, and the proportion of the global population living in poverty declined significantly.

In research released today for Copenhagen Consensus 2012, Hans-Peter Kohler of the University of Pennsylvania looks at sub-Saharan African nations that, among high-fertility countries, make the dominant contribution to world population growth. These nations are among the poorest and most vulnerable in the world, often having weak institutions and capacities to manage population growth.

“High-fertility” countries today account for about 38 percent of the 78 million people that are added annually to the world population, despite the fact that they are home to only 18 percent of the population. After 2060, the world’s population is projected to grow exclusively as a result of population growth in today’s high-fertility countries.

Kohler notes that the overall Sub-Saharan African population increase peaked in the early 1980s and has been declining from its pinnacle of 2.8 percent from 1980 to 85 to 2.5 percent from 2005 to10, although growth remains more than twice as high as the global rate.

The overall growth rate masks substantial variation. Nine countries are expected to more than triple their population between 2010 and 2060, with population growth rates between 2.2 and 3.0 percent: Burkina Faso, Niger, Zambia, Malawi, Somalia, Tanzania, Uganda, Mali, and Madagascar.

Many high-fertility Sub-Saharan African countries have a considerable—and possibly growing—“unmet need” for family planning: This means women who are not using any contraception but do not want more children, or want to delay the next child. About 25 percent of sexually active women would like to limit their fertility but do not use family-planning methods.

Family-planning programs that facilitate a decline in fertility and a reduction in population growth rate would seem to be potentially highly beneficial interventions that should be expanded. And yet, as Kohler outlines, this conclusion has been subject to a long-standing and sometimes heated debate, often questioning the very basic pillars of this deduction.

This debate has sometimes raised more questions than answers: How detrimental, if at all, is population growth for economic development, individual well-being, and the attainment of development indicators such as the Millennium Development Goals? Do family-planning programs have causal effects toward reducing fertility, or would observed declines in fertility areas also have been observed in the absence of these programs? Is there a window of opportunity in coming decades in which declines in population growth could provide a “demographic dividend” that would facilitate the social and economic development in some of the world’s most developed countries?

In the last two decades, a growing body of research has substantially strengthened the case for family-planning programs—documenting, for example, the significant effects of these programs toward reducing fertility, increasing education for mothers, improving women’s general health and longer-term survival, increasing female labor force participation and earnings, as well as child health.