Screen grab from UN DESA video "Population growth, environmental degradation and climate change"

New UN Report: Global Population Growth and Sustainable Development

Written by Marian Starkey, Vice President for Communications | Published: March 10, 2022

“During 2020, the world’s population increased by 81 million people, adding to the demand for food, housing, infrastructure, services and decent work, and increasing the pressure on the environment.”

That’s a sentence from page 22 of a new report[1] from the United Nations Population Division. The authors of Global Population Growth and Sustainable Development say there’s a 95% probability that the world population will be between 9.4 and 10.1 billion in 2050, up from 7.9 billion today. Working to achieve the lower end of that range through improved access to voluntary family planning is the primary aim of Population Connection in the coming decades, since the slower we grow, the sooner we’ll peak.

Even if we do succeed in slowing growth so that we “only” reach 9.4 billion by mid-century, that’s still 1.5 billion more people than are on the planet today. In other words, we are all but guaranteed to add the equivalent of more than another China or India to the world’s population in the next 30 years. Most of that growth will occur in sub-Saharan Africa, which is projected to double in size, to 2–2.2 billion. This is concerning given that health and educational outcomes are already the worst in the world among the least developed countries in that region—rapid population growth will only add to the existing struggle to ensure adequate natural resources and access to health care, education, and employment opportunities, condemning future generations to poverty and precarious access to life’s most basic needs.

Rapid population growth and slow progress in development tend to go hand in hand and may even be mutually reinforcing. For example, rapid population growth can exacerbate the challenge of eradicating poverty, potentially trapping countries and communities in a vicious cycle where economic growth may not keep pace with population growth, and where therefore the increase in per capita income may be insufficient to eradicate poverty, end hunger and malnutrition, and ensure universal access to health care, education and other essential services. At the same time, poverty, lack of education and gender inequality can deprive individuals of opportunities and choices, limiting their ability to control their fertility, perpetuating high levels of childbearing often starting early in life and ensuring the continued rapid growth of the population. (pp. 65)

For the next three or four decades, population growth is all but inevitable, due to population momentum—today’s young age structure guarantees a large cohort of people entering their reproductive years in coming decades, so even if fertility rates continue to decline, the sheer number of people having babies will keep the world population growing. However, fertility levels during the next few decades will determine the size of the childbearing population thereafter, which will have a compounding or cumulative effect on the level of population growth in the second half of this century. In the shorter term, delaying childbirth and extending the length of time between births increases the length of generations, which helps to reduce the force of population momentum, slowing population growth without necessarily reducing people’s completed family sizes.

Sustainable Development

Although the report is about population growth and sustainable development, its authors are careful to balance statements about environmental impacts of population growth with even stronger ones about the environmental repercussions of high consumption in high- and upper-middle-income countries, which have low fertility and slow population growth.

In 2017, the material footprint per capita of high-income countries was over 10 times that of low-income countries. The footprint has been increasing especially rapidly in the upper-middle-income countries as their GDP per capita grew rapidly. Given the gap in material footprint per person between countries at different income levels, the primary responsibility for “doing more and better with less” lies with countries that have the most unsustainable patterns of resource use, namely the high-income and upper-middle-income countries, where populations are growing slowly if at all. Limiting the footprint of countries where resource consumption is highest will also help offset some of the environmental impacts of achieving more rapid economic growth in countries where income per capita is currently low and populations are growing rapidly. These countries will require sustained and inclusive economic growth if they are to eliminate poverty and hunger and advance other aspects of human well-being. (pp. 97)

Important to keep in mind is that development efforts aimed at helping low-income countries out of poverty will inevitably raise consumption levels of fast-growing populations. The environmental impact of more people consuming more of everything—including fossil fuels—will be catastrophic if we don’t switch to more sustainable energy sources, farming practices, and resources extraction.

Environmental damage often arises from economic activities that lead to higher standards of living, especially when social and environmental costs are not factored into decisions about production. Pollution of air, water and soil, scarring of landscapes, destruction of habitats, waste and other aftereffects of production and consumption are often left out of economic decision making. …  In such situations, although population growth itself may not be the direct cause of environmental damage, it may nevertheless exacerbate the problem or accelerate the timing of its emergence. (pp. 97)

One contributor to regional environmental degradation that is very closely correlated to population growth is agriculture. In the absence of irrigation, seed, and soil improvements to increase crop yields on existing agricultural lands in places where people survive on subsistence farming, more land must be cleared for crops to feed growing regional populations.

For environmental problems linked to the expansion of agricultural land, such as habitat loss and reduced biodiversity, lower population growth would help reduce the need to bring more land under cultivation, although higher-yielding crop varieties and other land-sparing measures could also help in this regard. (pp. 97)

As the world looks to scale up food production to feed a growing population over the coming decades, it is important to recognize that current food and agricultural systems are unsustainable due to their devastating impacts on the planet and on human health. (pp.72)

Family Planning and Fertility Decline

At the same time that the global economy needs to be decoupling development and environmental destruction, countries and donors need to be expanding access to voluntary comprehensive reproductive health services, including contraception and safe abortion. There are an estimated 218 million women in the developing world who have an unmet need for contraception. And here in the United States, where per capita consumption is among the highest in the world, 45% of pregnancies and 37% of births are unintended. If every woman was able to make her own childbearing decisions in accordance with her own beliefs and desires, fertility rates would decline and population growth would slow. This would facilitate poverty alleviation, women’s empowerment, and educational attainment (especially among girls), and would alleviate some of the pressures on the environment that rapid population growth exacerbates.

In their brief discussion of carrying capacity, the report’s authors state that even with today’s population, the earth couldn’t support everyone consuming at the levels observed in high-income countries. The authors support “greatly increased efforts towards decoupling economic growth from adverse environmental impacts” in order to reduce the ecological footprint of high-income people and make room for the increased consumption among low-income people.

The number of people that the Earth can support depends to an important degree on how carefully the planet’s resources are managed and how equitably they are shared. However, it has become clear that the planet could not sustainably support even its current population if everyone had levels of consumption similar to those found in today’s high-income countries, relying on today’s technologies. The level of development and well-being in many high-income countries today has been achieved largely through highly resource-intensive patterns of consumption and production, which are not sustainable or replicable in other parts of the world (UNEP, 2016). (pp. 96)

The report’s authors clearly outline the most impactful ways high-fertility countries could slow their population growth through policies and programs that respect human rights, improve gender equality, and respond to existing needs:

Stronger efforts to reduce the unmet need for family planning, to raise the minimum legal age at marriage, to integrate family planning and safe motherhood programs into primary health care and to improve female education and employment opportunities could help ensure a more rapid fertility decline in low-income countries with rapidly growing populations and thus accelerate their progression into the period of the demographic dividend, during which an increased concentration of population in the working ages is conducive to more rapid economic growth. (pp. 100)

After all, “Continuing rapid population growth is partly the result of a failure to ensure that all people, everywhere, have the knowledge, ability and means to determine whether and when to have children.” (pp. 21)

Download the Global Population Growth and Sustainable Development report, policy brief, and key messages on the UN Population Division website.

[1] Disclosure: A member of our Board of Directors, Mary Beth Weinberger, a consultant to the Population Division, helped prepare and review the report for publication.