The world’s population is expected to hit 8 billion this week. 

On 15 November 2022, the population is projected to reach the new milestone in human development. 

While fertility rates in many advanced nations are slowing or going backwards, continued growth is occurring due to a gradual increase in human lifespan from improvements in public health, nutrition, personal hygiene and medicine. It is also the result of high and persistent levels of fertility in some countries.

While it took the global population 12 years to grow from 7 to 8 billion, it will take approximately 15 years - until 2037 - for it to reach 9 billion, a sign that the overall growth rate of the global population is slowing.

Projections by the United Nations suggest that the global population could grow to around 8.5 billion in 2030, 9.7 billion in 2050 and 10.4 billion in 2100. 

Countries with the highest fertility levels tend to be those with the lowest income per capita. Global population growth has therefore over time become increasingly concentrated among the world’s poorest countries, most of which are in sub-Saharan Africa.

Stats show that life expectancy at birth for women in 2019 exceeded that for men by 5.4 years globally, with female and male life expectancies standing at 73.8 and 68.4, respectively. 

A female survival advantage is observed in all regions and countries, ranging from 7 years in Latin America and the Caribbean to 2.9 years in Australia and New Zealand.

In 2021, the average fertility of the world’s population stood at 2.3 births per woman over a lifetime, having fallen from about 5 births per woman in 1950. 

Global fertility is projected to decline further to 2.1 births per woman by 2050.

In 2020, the global population growth rate fell under 1 per cent per year for the first time since 1950. 

As life expectancy continues to increase, the world’s population gets older. 

Population growth is in part caused by declining levels of mortality, as reflected in increased levels of life expectancy at birth. 

Global life expectancy at birth reached 72.8 years in 2019, an improvement of almost 9 years since 1990.

Further reductions in mortality are projected to result in an average global longevity of around 77.2 years in 2050. Yet in 2021, life expectancy for the least developed countries lagged 7 years behind the global average. 

Similarly, a male disadvantage in life expectancy is observed in all regions and countries, ranging from 7 years in Latin America and the Caribbean to 2.9 years in Australia and New Zealand. 

The population above age 65 years is growing more rapidly than the population below that age. As a result, the share of global population at ages 65 and above is projected to rise from 10 per cent in 2022 to 16 per cent in 2050. 

At that point, it is expected that the number of persons aged 65 years or over worldwide will be more than twice the number of children under age 5 and about the same as the number under age 12. 

Countries with ageing populations are being warned to take steps to adapt public programmes to the growing numbers of older persons, including by establishing universal health care and long-term care systems and by improving the sustainability of social security and pension systems. 

Even though population growth magnifies the environmental impact of economic development, rising per capita incomes are the main driver of unsustainable patterns of production and consumption. 

The countries with the highest per capita consumption of material resources and emissions of greenhouse gases tend to be those where income per capita is higher, not those where the population is growing rapidly.

Even so, more and more countries are experiencing population decline. 

Fertility has fallen markedly in recent decades for many countries. Today, two-thirds of the global population lives in a country or area where lifetime fertility is below 2.1 births per woman, roughly the level required for zero growth in the long run for a population with low mortality. 

The populations of 61 countries or areas are projected to decrease by 1 per cent or more between 2022 and 2050, owing to sustained low levels of fertility and, in some cases, elevated rates of emigration.

For high-income countries between 2000 and 2020, the contribution of international migration to population growth (net inflow of 80.5 million) exceeded the balance of births over deaths (66.2 million). 

Over the next few decades, migration will be the sole driver of population growth in high-income countries. 

By contrast, for the foreseeable future, population increase in low-income and lower-middle-income countries will continue to be driven by an excess of births over deaths. 

The UN’s summary of world population prospects is accessible in PDF form, here.