How the world’s population reached 8 billion people - but when will it hit 9 billion?

Global population reaches 8 billion people and is rising   (Dan Dennison/Getty Images)
Global population reaches 8 billion people and is rising (Dan Dennison/Getty Images)

The world’s population has reached eight billion people, according to recent UN estimates.

In 2011, humanity passed the seven-billion milestone, which means, over the past 11 years, there are now another one billion people on the planet. This increase is set to hit nine billion in 2037 – 15 years from now.

It adds further worry as leaders battle to tackle issues such as food security, climate change, ageing populations, and environmental destruction.

Despite the human population steadily rising, growth has remained slow, including birth rates falling across much of the world. The world population is growing more slowly than it has in decades due to long periods of low fertility. However, falling birth rates are also due to easier access to contraception and better education.

But with birth and fertility rates falling, why is the world’s population increasing?

Population momentum

According to Our World in Data, at times when an increasing share of women enter the reproductive age bracket, the population can keep growing, even if the fertility rate is falling.

Known as “population momentum”, it explains why the number of children globally will not decline as quickly as the fertility rate.

“Population momentum is one important driver for high population growth,” said the site.

Longer life expectancies

Another major reason why the global population is increasing is that many of us live much longer than our ancestors, even only a few generations ago.

At the turn of the 20th century, global life expectancy started steadily rising, with most people living both longer and healthier lives than ever before.

Extended life expectancies, made possible because of modern medicine, advancements in public health, nutrition, and sanitation, is now twice as long in all world regions.

In fact, the UN has predicted that life expectancy is forecast to rise from aged 72.98 in 2019 to 77.2 in 2050, and the proportion of people aged 65 will rise from 10 per cent of the population in 2022 to 16 per cent in 2050.