Investing $10 billion a year in family planning could keep the world population at around 6 billion in 2100 (Image: Sipa Press/Rex Features)

Will there be 15.8 billion people inhabiting the world in 2100, or 6.2 billion? The first scenario might trigger harsh resource shortages, unrest and war; the latter features a stable planet with hope for all.

As this century proceeds, more and more of the population growth will be driven by the least developed countries. Most are in Africa, which has an average family size of 4.7 children per woman. It is the only continent where population is predicted to keep growing beyond 2100.

If Africa’s population increases according to the UN’s medium prediction, the continent will have about 3.6 billion people by the end of the century – raising its current share of global population from 12 per cent to about one-third. Nevertheless, its population could reach 5.2 billion or 2.4 billion by 2100, depending on whether fertility is 0.5 children above or below the UN’s medium estimate.


The population of the Sahel – those semi-arid countries bordering the Sahara – will double or more by 2050 at exactly the time that global warming is likely to have the harshest effects. As population growth and global warming coincide, the hunger and refugee problems in the Horn of Africa, and type of resource battles seen in Darfur or South Sudan, will multiply.

Worldwide, the UN predicts 15.8 billion humans by the end of the century if average family size remains around 2.6 children per woman, but 6.2 billion if it stabilises at 1.6 children. If fertility levels drop to the replacement level of 2.1, then there will be 10 billion people.

This week the Royal Society launched a new report called People and the Planet. It reviews the evidence on the link between population and global challenges, underscoring the need to move to a biologically sustainable economy as well as lifting the poorest 1.3 billion people out of abject poverty.

The report explores the impacts of population changes on general wellbeing, urbanisation, food and water security, and the risk of conflict. It also emphasises the need to reduce excessive consumption in developed countries and emerging economies. Crucially, the report calls for investment in voluntary family planning, and in the education and wellbeing of girls in the least developed countries in order to slow population growth.

Changing habits

Africa remains the region with the lowest use of contraceptives (29 per cent of married women of reproductive age versus the global average of 69 per cent) and a high demand for children. However, things are changing. It is possible to manage population growth if local governments, the international community and others make the right decisions and provide the right support.

In developing countries between the 1970s and 1990s, cultural sensitivity surrounding childbearing was prevalent, as were suspicions over the intentions of western development partners in promoting family planning. Such sentiments, however, have largely dissipated.

Leaders are becoming more receptive to addressing population issues due to the growing evidence that high growth undermines efforts to ease poverty and hunger, and that investing in quality human capital is needed to transform their economies.

The economic turbulence experienced by most developing countries since the 1980s also makes it clear that it will be difficult or impossible to break their development shackles without curbing rapid population growth.

Leaders who were once reluctant to promote family planning have joined the family planning bandwagon, thanks to scrutiny of their progress towards the Millennium Development goals (including poverty, equality and sustainability), coupled with the increasing evidence that family planning plays a central role in improving maternal and child health.

Furthermore, although leaders embrace big populations as symbols of political power, a source of global influence and a potential economic asset, it is increasingly apparent that development goals are better met through high quality populations rather than big ones.

The political will and commitment to promote family planning and reduce population growth is not as entrenched in the highly populated countries of central and west Africa as it is in northern, southern and parts of eastern Africa. But it is instructive that virtually all African countries now acknowledge rapid population growth as one of the key impediments to development.

For example, Rwanda has seen one of the fastest increases in history in use of modern contraceptives – from 6 per cent of married women of reproductive age in 2000 to 45 per cent in 2010. Malawi, which banned family planning between 1969 and 1984, has one of Africa’s highest levels of modern contraceptive use – 42.2 per cent – in 2010.

And while many African leaders could once argue that it was against African culture to promote family planning, the evidence over the past two decades shows that most women are having more children than they would like, and many would like to postpone their next birth.

Across the globe, 215 million women report unmet need for family planning. In most African countries, the majority of women of reproductive age have unmet family planning needs. In sub-Saharan Africa, 42 of the 78 million women who need family planning are not using modern contraception. About two in five women in Ghana, Zambia, Malawi and Togo recently reported that their last birth was unplanned.

This is due to a lack of services, disapproval of family planning, misinformation, misconceptions and medical barriers, such as limiting oral contraceptive use to medical prescription. These barriers can be addressed through voluntary family planning programmes that are well-planned, appropriately funded, with strong community involvement and mobilisation.

Girls who stay in school longer have fewer children because they marry later. They are also more likely to want fewer children as they want to pursue a career and enjoy greater power to negotiate contraception use.

Governments should legislate against child marriages, and young people deserve youth-friendly reproductive health services. Unfortunately, family planning is not high on the development priority list in many least developed countries and is subsequently under-funded. The international community needs to step in. Evidence shows that in such cases, governments slowly assume funding responsibility.

The Royal Society report suggests that offering family planning through appropriate clinical, commercial and community channels could cost about $6 to 7 billion per year. It would cost perhaps another $1 billion to keep half of 15 to 19-year-old girls in the fastest-growing least developed countries in school instead of entering into child marriage.

An overall investment of $10 billion a year today could begin to move global population towards 6 billion in 2100. Taking no action will cost many times more. The pace of technical change, global warming, competition for resources and short-term national rivalries point to problems in the future.

There is no way to guarantee a safe future, but the commonsense view is that a world of 6 or 7 billion people with reasonable living standards for most is a better bet than one with 12 to 16 billion in which 5 to 6 billion struggle to survive on a few dollars a day while the richest continue to consume too much, and women are still denied their freedom.

At less than one thousandth of global GDP, $10 billion dollars per year could potentially change the course of the 21st century.

Author Profile: Eliya Msiyaphazi Zulu is the founder and executive director of the African Institute for Development Policy, which promotes use of research and related evidence in decision-making processes related to population change, reproductive health and sustainable development in Africa. He was a member of the Royal Society study group that produced the report People and the Planet.