Although population growth in the 20th and 21st centuries has rocketed, it can be slowed, stopped and reversed. Under the United Nations’ most optimistic scenario, a sustainable reduction in global population could happen within decades.

We need to take action to reduce the impact of those of us already here, including through reducing consumption to sustainable levels.

The most effective step we can take to achieve both goals – reducing our environmental impact and ending population growth – is to limit our family size.

Baby feet

A little less makes a lot of difference

The United Nations makes a range of projections for future population growth, based on assumptions about how long people will live, what the fertility rate will be in different countries and how many people of childbearing age there will be. Its main population prediction is in the middle of that range – 9.7bn in 2050 and 10.9bn in 2100.

It also calculates that if, on average, every other family had one fewer child than it has assumed (i.e. 'half a child less' per family), there will be one billion fewer of us than it expects by 2050 – and nearly four billion fewer by the end of the century (within the lifetimes of many children born now). If that happens, our population will be less than it is today.


We can bring birth rates down

Countries have had success in reducing their birth rates. Thailand, for instance, reduced its fertility rate by nearly 75% in just two generations with a targeted, creative and ethical family planning programme.

In the last ten years alone, fertility rates in Asia have dropped by nearly 10%.

population projections +- half a child 2019

Educating girls

Where women and girls have economic empowerment, education and freedom, they choose to have smaller families. Greater freedom usually leads to greater uptake of family planning and ending child marriage pushes back the age at which women have their first child which often reduces family size.

For instance, African women with no education have, on average, 5.4 children; women who have completed secondary school have 2.7 and those who have a college education have 2.2. When family sizes are smaller, that also empowers women to gain education, take work and improve their economic opportunities.


Removing barriers to contraception

Currently, more than 200 million women who want to avoid pregnancy are not using modern contraception. There are a variety of reasons for this, including lack of access to contraceptives, concerns about the side-effects of contraception and social pressure not to use it.

These women mostly live in some of the world’s least developed countries, where population is set to rise by 3bn by 2100. Overseas aid support for family planning is essential – both ensuring levels are high enough and that delivery of service is effective.


Only 39% of countries have equal proportions of boys and girls enrolled in secondary education.

Challenging assumptions about family size and contraception

Across the world, people choose not to use contraception because they are influenced by assumptions, practices and pressures within their nations or communities. In some places, very large family sizes are considered desirable; in others, the use of contraception is discouraged or forbidden.

Work with women and men to change attitudes towards contraception and family size has formed a key part of successful family planning programmes. Religious barriers may also be overturned or sidelined. In Iran, a very successful family planning campaign was initiated when the country’s religious leader declared the use of contraception was consistent with Islamic belief. In Europe, predominantly Catholic countries such as Portugal and Italy have some of the lowest fertility rates.


Alleviating poverty

The UN projects that population growth over the next century will be driven by the world’s very poorest countries. Escaping poverty is not just a fundamental human right but a vital way to bring birth rates down. Decreasing child mortality, improving education and providing people with economic opportunities all help to reduce fertility and population growth. International aid, fair trade and global justice are all tools to help bring global population back to sustainable levels.

Exercising the choice

In the developed world, most of us have the power to choose the size of our families. We also have a disproportionate impact on the global environment through our high level of consumption and greenhouse gas emissions – in the UK, for instance, each individual produces 70 times more carbon dioxide emissions than someone from Niger. When we understand the implications for our environment and our children’s futures of a growing population, we can consider having smaller families.

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