Help WRI turn ideas into action all over the world.

You are here

Achieving Replacement Level Fertility

Creating a Sustainable Food Future, Installment Three

The United Nations projects that world population will rise from just over 7 billion in 2012 to nearly 9.6 billion by 2050. This paper examines the nature of the population challenge globally, the effect of population growth on food demand in Sub-Saharan Africa, and the potential benefits―in terms of food security, economic growth, and environment―of reducing fertility levels more quickly than currently projected. This paper then explores promising, non-coercive approaches for reducing fertility rates.

This is the third installment in the series that forms the foundation of the “World Resources Report 2013-14: Creating a Sustainable Food Future.”

Executive Summary

The world’s population will rise from just over 7 billion in 2012 to nearly 9.6 billion by 2050. Most of the world’s regions have already achieved or are close to achieving replacement level fertility. “Replacement level fertility” is the total fertility rate—the average number of children born per woman—at which a population exactly replaces itself from one generation to the next, without migration. This rate is roughly 2.1 children per woman for most countries, although it may modestly vary with mortality rates.

Sub-Saharan Africa is the exception to this fertility trend. Its total fertility rate was 5.4 during the 2005–10 period― double that of any other region―and is projected to decline only to 3.2 by 2050. These expected reductions in fertility rates reflect expectations of increasing urbanization, expected declines in child mortality, and increases in income, among other factors. This total fertility rate trajectory will result in a population increase of 1.2 billion people in Sub-Saharan Africa from 2012 to 2050. This increase will more than double the region’s current population of 0.9 billion to 2.1 billion by 2050, and quadruple it to 3.9 billion by 2100, according to the Population Division of the United Nations Department of Economic and Social Affairs (UNDESA). The region’s projected growth in population will account for half of the planet’s population growth between 2012 and 2050.

This projected increase in population poses a food security challenge for the people of Sub-Saharan Africa. The region is already the world’s hungriest. According to the Food and Agriculture Organization of the United Nations (FAO), 27 percent of Sub-Saharan Africa’s people are undernourished, while a study by the U.S. Department of Agriculture estimates that it is home to 44 percent of the world’s hungry people. The region currently has the world’s lowest crop yields, with cereal yields of 1.5 metric tons per hectare per year―roughly half the world average. Much of the soil has lower carbon content and is depleted of nutrients.

Sub-Saharan Africa could reduce the challenge of feeding its population if it were to achieve the replacement level fertility of 2.1 by 2050. Doing so would require a reduction in the region’s average total fertility rate at a faster pace than currently projected. According to analysis conducted for this working paper by the Oxford Institute of Population Ageing, such a reduction would result in a Sub-Saharan African population of 1.76 billion by 2050—roughly 390 million less than UNDESA’s most recent medium fertility scenario projection for 2050.

Achieving replacement level fertility in Sub-Saharan Africa by 2050―and ensuring it is achieved as projected in other regions―could generate a number of benefits. It would reduce food demand by roughly 600 trillion kilocalories (kcal) per year by midcentury, closing about 9 percent of the 6,500 trillion kcal per year global gap between food available in 2006 and that needed in 2050. More dramatically, it would reduce the size of the projected gap in Sub-Saharan Africa’s crop production for that period by approximately one quarter. The region already relies on imports for roughly 20 percent of its staple crops, so closing this food gap would significantly contribute to food security.

Reducing fertility rates could also lead to economic benefits through a “demographic dividend.” During and after a rapid decline in fertility, a country simultaneously has fewer children to care for and a greater share of its population in the most economically productive age bracket. Researchers estimate that this demographic shift was responsible for up to one third of the economic growth of the East Asian “Tigers” between 1965 and 1990. Furthermore, achieving replacement fertility would reduce agriculture’s impact on the environment. Based on FAO projections for yield gains in the region, Sub-Saharan Africa will need to add more than 125 million hectares of cropland from 2006 levels to meet the region’s projected crop needs in 2050. Achieving replacement level fertility would cut needed cropland expansion by one third, potentially sparing an area of forest and savannah larger than Germany from conversion. This sparing would reduce the carbon emissions that would have resulted from that conversion. A reasonable value for this reduction to the world would be US$400 billion to US$1 trillion, based on alternative mitigation costs of US$25 to US$60 per ton of carbon dioxide.

Fortunately, the most effective approaches to achieving replacement level fertility are non-coercive, save millions of lives, advance gender equity, give people more control over their lives, and contribute to economic growth. These approaches focus on increasing educational opportunities for girls; increasing access to reproductive health services, including family planning; and reducing infant and child mortality.

In most countries, national governments control, fund, and set policies for education systems and health services. Pursuing the approaches noted above for achieving replacement level fertility is, therefore, the responsibility of national governments. However, bilateral and multilateral development agencies also have a role to play by supporting programs that advance gender equity in education, reproductive health services, and nutrition and preventative health services for children under the age of five. Civil society organizations can help as well by raising awareness, generating resources, delivering services, and monitoring performance.

The most recent population data find that Sub-Saharan African fertility rates have not been declining as rapidly as anticipated by previous UNDESA projections. Yet countries such as Botswana and Rwanda have demonstrated that enormous progress is possible. Achieving replacement level fertility in Sub-Saharan Africa and elsewhere by 2050 is a multi-win solution to humanitarian, economic, and environmental challenges, and an important item on the menu for a sustainable food future.

Stay Connected

Sign up for our newsletters

Get our latest commentary, upcoming events, publications, maps and data. Sign up for the weekly WRI Digest.