Slowing growth

The global population continues to grow, at 8 billion and counting. But after half a century of falling fertility, this growth is slowing down.

Global population change comes down to birth and death.

The dynamics behind fertility and mortality are complex, but if there are more births than deaths, the population grows.

While the balance depends on the context – including environmental, social, economic and political factors – change follows certain patterns, known as the demographic transition.

This process began as improved nutrition, health care, living conditions and education – and expanded choices, especially for women and girls – led to lower child mortality, longer lives and fewer births per woman.

At first, falling mortality drove spectacular population growth, peaking at 2.1% per year between 1962 and 1965. Between 1950 and 1987, the population doubled, from 2.5 to 5 billion.

But as fewer children were born from generation to generation, growth started to slow. In 2020, it fell below 1% per year for the first time since the 1950s.

Over the next few decades, population momentum will keep us growing. Past growth – from previous generations with higher fertility – means that we have large and still rising numbers of women of reproductive age. Despite fewer births per woman, we’ll continue to see more births than deaths.

Even if fertility fell to replacement level (about 2 births per woman) today in all countries where it’s higher than that, enough children would be born to keep us growing through at least 2060.

But as fertility continues to fall – and life expectancies rise – older people represent an ever-growing share of our population.

As these large generations of older people begin to die, the number of deaths will outpace the number of births. Population growth will slow further, and may decline.

We project that our population will peak at 10.4 billion in the 2080s, and stay there through the end of the century.

The same overall patterns apply when we look at regions, countries and areas – although a third factor, international migration, comes into play.

The demographic transition has happened at different rates in different parts of the world, with different environmental, social, economic and political factors affecting the balance of births and deaths, in-migration and out-migration.

Across countries, populations are growing at different rates.

Some are growing faster than the global average, others slowing or even shrinking. Across this stunning diversity, the only constant is change.

Fewer children

While fertility varies across regions and countries, rates are falling everywhere. And in some countries, populations are shrinking.

The global fertility rate – the average number of births per woman – has been falling for decades. Reductions in fertility are associated with factors including expanded opportunities for girls’ and women’s education and workforce participation, delayed marriage and childbearing, and increased access to contraception.

Back in 1950, global fertility stood at 5 births per woman. As of 2022, it’s at 2.3, projected to fall to 2.1 by 2050.

As relatively fewer children are born – while longer life expectancies drive growing populations at older ages – the share of children (ages 0-14) in the global population is declining.

Globally, we’re getting close to replacement-level fertility – where in the long run a population no longer grows, but maintains equal numbers from generation to generation. This rate depends on mortality and, at the level of countries or areas, also on migration. Given our low average mortality rates, the fertility rate for zero growth stands at about 2.1 births per woman.

Already, over 60% of people – up from 40% in 1990 – live in a country or area where fertility is below replacement level.

Even where it’s high enough to sustain positive growth – in sub-Saharan Africa, Oceania (except Australia and New Zealand), northern Africa and western and southern Asia – it’s still falling. Except in sub-Saharan Africa, it is expected to fall below replacement level in all regions by the end of the century.

In some low-fertility countries, populations are still growing because of population momentum. This is the case in India, which in 2023 will overtake China as the world’s most populous country, despite fertility already below 2.1 births per woman, and falling.

In other countries, populations are shrinking after decades of low fertility – exacerbated, in some cases, by high levels of emigration. In 17 countries of Eastern Europe, both factors have contributed to population decline since 1990.

Looking ahead, more countries, especially in Southern Europe and East Asia, are beginning to see their populations decline – including China, projected to start shrinking as early as 2023. Between 2022 and 2050, the populations of 61 countries are expected to shrink by over 1%. Among them, Bulgaria, Latvia, Lithuania, Serbia and Ukraine may see reductions of 20% or more.

Longer lives

Life expectancy is rising globally, but huge disparities persist.

Across the world, people are living longer. In 2019, global life expectancy at birth stood at 72.8 years, up almost 9 years since 1990 – and it’s projected to rise to 77.2 years by 2050.

Life expectancy refers to the average number of years a person of a particular age can expect to live, given overall death rates in their population. We typically measure it at birth and at age 65.

Life expectancy at birth has been rising since the 1950s in all regions, especially as death rates from infectious diseases have fallen. There have been measureable setbacks – related to the 1957 influenza pandemic and, more recently, HIV/AIDS and COVID-19.

But overall, the trend has been towards lower mortality – including lower under-five mortality – and longer lives, linked to factors including better nutrition, health care and living conditions.

But the extent to which these conditions hold varies greatly across the world, both among countries and within them. While mortality has fallen in all regions, there are significant disparities.

In low-income countries, life expectancy at birth is about 63, or nearly 10 years below the global average.

Disparities in under-five mortality account for a large part of the gap. A child born in a low-income country is over 13 times more likely to die before age 5 than one born in a high-income country. Higher mortality rates also reflect high maternal mortality and, in some countries, violence, conflict and the continuing impacts of HIV.

The gap in life expectancy at birth can be as much as 33.4 years.

While a newborn in Australia, Hong Kong SAR, Macao SAR or Japan – where it’s highest – can expect to live 85 or more years, a newborn in the Central African Republic, Chad, Lesotho or Nigeria – the countries with the lowest life expectancies – can expect to live less than 54 years.

Looking ahead, the gaps are narrowing, as life expectancy rises in many countries that today have lower life expectancies, while the rise in life expectancy slows in today’s low-mortality countries.

Still, the gaps are not narrowing fast enough. In 2050, life expectancy at birth in low-income countries is projected to be about 8.4 years less than the global average. And a baby born in the countries with the lowest life expectancies today may still live an average of 31.8 years less than a baby born in those with the highest life expectancies.

People on the move

International migration is reshaping populations. In some low-fertility countries, immigration sustains population growth – while in others, emigration compounds population decline.

At the level of regions, countries and areas, international migration shapes population change, alongside fertility and mortality. It’s harder to project than the other two, because of incomplete data and migration patterns that can change rapidly depending on what’s going on across the world.

While nearly 29 out of every 30 people stay in their country of birth, the number of people moving across borders is rising.

It’s expected to rise further – including as a result of the worsening impacts of climate change.

As of 2020, an estimated 281 million people lived outside their country of birth – 128 million more than in 1990 and three times as many as in 1970. Nearly two thirds were labour migrants. As of the end of 2021, international migrants also included 31.7 million refugees and asylum seekers.

Between 2010 and 2021, 40 countries and areas saw net inflows of over 200,000 migrants each – and in 17 of them, over 1 million each.

In 2020, Türkiye hosted the largest number of refugees and asylum seekers – almost 4 million. Jordan hosted 3 million, the State of Palestine, 2 million, and Colombia, 1.8 million. Germany, Lebanon, Pakistan, Sudan, Uganda and the United States also hosted large numbers of refugees, asylum seekers and other displaced people.

Ten countries saw net outflows of over 1 million during the same period. 16.5 million people left Pakistan, 3.5 million left India, 2.9 million left Bangladesh, 1.6 million left Nepal and 1 million left Sri Lanka. Most of these emigrants left temporarily, in pursuit of work.

Emigration from other countries has been driven by insecurity and conflict. As of the end of 2021, 6.8 million people had left Syria as refugees, while 4.6 million had left Venezuela; 2.7 million, Afghanistan; 2.4 million South Sudan; and 1.2 million, Myanmar.

Staggering numbers of people may be displaced over a short time – between 24 February and 19 October 2022, for instance, an estimated 7.7 million people fled Ukraine, crossing into neighbouring countries, including Poland and Moldova.

For some countries, migration makes a critical difference in terms of population change – sustaining growth or compounding decline.

In high-income countries, which have seen low fertility for decades, migration was a bigger factor contributing to population growth than births during the period 2000-2020 – and it will be the sole driver of population growth in the coming decades.

In other countries, including in Eastern Europe, more people are leaving than are coming in – and together with falling fertility, this high net emigration is driving population decline.

Ageing populations

As fertility declines and life expectancy rises, the global population is ageing fast.

As a global population, we’re getting older, and it’s happening faster than ever. Between 1950 and 1990, the share of people 65 and over in the population rose from about 5% to about 6%. As of 2022, it stands at nearly 10%, projected to rise to 16% by 2050.

In many countries, large generations of children who were born in past decades of sustained high fertility are now ageing. In others, incremental improvements in survival across several generations are driving the growth of older populations.

Global life expectancy at age 65 – the average number of additional years a 65-year-old person can expect to live – is rising. It’s now at 16.3 years, and was at 17.5 before COVID-19 hit older populations disproportionately hard. By 2050, it’s projected to rise to 19.8 years, as deaths from noncommunicable diseases like cardiovascular disease or diabetes fall further.

Because fertility has been falling at the same time as people have been living longer, the age structure of the population is shifting. In 2018, for the first time ever, people aged 65+ outnumbered children under 5.

By 2050, the number of people aged 65+ will be over twice the number of children under 5, and about the same as the number of children under 12.

Different regions are ageing at different rates.

Europe and northern America have the oldest populations, with almost 19% of people aged 65+, followed by Australia and New Zealand, with 16.6%. By 2050, 1 in 4 people in Europe and northern America will be 65 or older.

All other regions will see their share of people aged 65+ rise quickly, too – for example, from 9% in 2022 to 19% in 2050 in Latin America, and from 13% to 26% in eastern and southeastern Asia.

But because some regions are still relatively young, people aged 65+ will continue to make up much smaller shares of their populations – despite growth of over 3% per year among this age group. In sub-Saharan Africa, the region with the youngest population, the share of people 65+ is projected to grow from 3% in 2022 to 5% in 2050.

Women outliving men

More boys than girls are born worldwide, but women outlive men nearly everywhere. The result is a global population in which men only slightly outnumber women.

Globally, nearly 106 boys are born for every 100 girls. This is within the biologically normal range of 102-106. (Anything above 106 would indicate that gender-biased sex selection is taking place.)

While born in greater numbers, boys are more likely to die during infancy and early childhood than girls, from conditions such as birth complications and infections. As of 2020, under-five mortality among boys was estimated at 39 deaths per 1,000 live births, versus 34 among girls.

Throughout adolescence and adulthood, males die in higher numbers because of factors like greater likelihood of risky behaviours, weaker immune systems and higher risks of cardiovascular disease at younger ages.

As a result, women outlive men on average. This gap in life expectancy is not unique to humans. It stems from a complex interaction of biological factors (some linked to males having just one X chromosome) and social or behavioural ones.

The female survival advantage holds despite the substantial impacts of gender inequality on girls’ and women’s survival and health, including greater likelihood of neglect during childhood, driven by the discriminatory social norm of son preference, and higher rates of poverty and hunger throughout life.

While women have higher rates of illness overall, they are more likely to survive them.

Where there are high rates of maternal mortality, though, this survival advantage is reduced.

Women’s life expectancy at birth is 5.4 years longer than men’s, on average. The gap ranges from 2.9 years in Australia and New Zealand to 7 years in Latin America and the Caribbean.

Over time, the gap has varied across countries and regions, shrinking in Europe and North America as well as Australia and New Zealand, but widening in Asia. In sub-Saharan Africa, it was on the rise until disproportionate female mortality from HIV/AIDS in the late 1990s-mid 2000s reduced it – though since COVID, it has now increased slightly.

With an average life expectancy at age 65 of 18.8 years, compared to 15.9 for men, women outnumber men in nearly all older populations, making up 55.7% of people aged 65+ globally in 2022. This gap increased slightly because of higher COVID-19 mortality among men, but is projected to decline by 2050, to 54.4% women, as men enjoy better health and lower mortality.

In the overall population, men outnumber women, but only slightly – 50.3% versus 49.7%, respectively, as of 2022. By 2050, the numbers of women and men are projected to be equal.

Two pandemics

COVID-19 had a measurable impact on mortality. For regions hardest-hit by the earlier HIV/AIDS pandemic, it erased hard-won gains in life expectancy.

Over just two years, the COVID-19 pandemic had a measurable impact on the population, especially on mortality.

In 2020 and 2021, it led to 14.9 million more deaths than expected based on previous years’ estimates. Three times the officially reported number of COVID-19 deaths, this number includes indirectly related deaths, such as deaths from other health conditions – including HIV/AIDS – for which people couldn’t get treatment or preventive care. Of these deaths, over half were in lower-middle-income countries.

Between 2019 and 2021, life expectancy at birth fell by 1.7 years globally.

The largest declines were in central and southern Asia (-2.3 years) and Latin America and the Caribbean (-1.5 years). Among countries, Bolivia, Botswana, Lebanon, Mexico, Oman and the Russian Federation saw COVID-related declines of more than 4 years.

While estimates show life expectancy already at pre-COVID levels in countries with high vaccine prevalence, those with low vaccine prevalence can expect a time lag of 1-3 years. Only 1 in 4 people in low-income countries have had at least one vaccine dose, compared to 3 in 4 in high-income countries.

COVID-19 hit a population already bearing the imprint of HIV/AIDS. Both pandemics have been characterized by unequal access to lifesaving tools and resources.

For some regions, there’s been a significant cumulative impact.

Worldwide, AIDS has killed over 40 million people since 1981, or nearly half of those infected with HIV. While HIV infection was initially a death sentence, the introduction of antiretroviral therapy (ART) cut AIDS deaths by 68%.

But while these lifesaving treatments were developed in the mid-1990s, they were unavailable to people in poorer countries – including in sub-Saharan Africa, where the pandemic’s toll was and continues to be heaviest – until the early/mid-2000s.

HIV/AIDS cost southern Africa, the hardest-hit subregion, two decades of potential improvements in survival rates. Between 1990 and 2005, life expectancy at birth fell from 63.1 years to 53.1. While it returned to its 1990 level by 2015 and increased to 65.5 years in 2019, COVID-19 erased those gains, bringing life expectancy back down to 61.8 years as of 2022.

Shifting centres

Regions are growing at different rates, shifting the geographical distribution of the global population.

As of 2022, over half the world’s people live in Asia. The world’s two most populous regions are eastern and southeastern Asia, home to 2.3 billion people, and central and southern Asia, with 2.1 billion.

India and China, each with over 1.4 billion people, make up most of the population in these two regions. China’s population is no longer growing, and may start declining as early as 2023 – when India, still growing at 0.7% per year, is set to surpass it as the world’s most populous country.

In eastern and southeastern Asia, fertility has seen a rapid decline since the 1960s, reaching replacement level in the early 1990s – slowing the region’s growth to just 0.2% per year as of 2022. Its population is projected to peak by the mid-2030s, at about 2.4 billion people.

In central and southern Asia, fertility declined more slowly, and the population is growing at 0.9% per year. The region is expected to become the world’s most populous by 2037, and to keep growing until it peaks at about 2.7 billion around 2072.

Meanwhile, sub-Saharan Africa has been the fastest-growing region since the 1980s. Its growth rate peaked at 3% per year in 1978, declining slightly since then to 2.5% in 2022 – still almost triple the current global average of 0.8%.

Sub-Saharan Africa’s population is projected to almost double between 2022 and 2050 – accounting for more than half of global population growth in that period, and reaching over 2 billion by the late 2040s.

By the late 2060s, sub-Saharan Africa is projected to become the most populous region, and could see its population reach 3.44 billion by 2100.

Latin America and the Caribbean, which quadrupled in size between 1950 and 2022 and is currently growing at 0.7% per year, will peak around 2056, and then begin to decline, though its share of the world population will decline only slightly.

The populations of Northern Africa and Western Asia, Oceania, and Australia and New Zealand will continue to grow through the end of the century, slightly increasing or maintaining their shares of the global population.

Europe and Northern America, which in 1960 accounted for over a quarter of the world’s people, has been growing at a rate of less than 1% per year since the mid-1960s, and is now close to zero growth.

As of 2022, its population, at 1.14 billion, is about the same as that of sub-Saharan Africa, as is its share of the global population, at about 14%. But projections show that the population of Europe and Northern America will start declining by 2038, with its share falling to about 11% by 2058.