A new study suggests that the Earth's population will decline in the next century and will not reach the previously predicted 11 billion.

Population growth could stall by 2050, and by 2100, the Earth's population could fall to as low as 6 billion, according to a new analysis of birth trends. The study, commissioned by the non-governmental organisation the Club of Rome, predicts that if current trends continue, the world's population, which is currently 7.96 billion, will peak at 8.6 billion by the middle of the century, but will fall by nearly 2 billion by the end of the century.

These forecasts are both good and bad news for humanity: a shrinking population will slightly alleviate the Earth's environmental problems, but it is by no means the most important factor in solving them.

Furthermore, as the population shrinks, humanity will generally become older and the proportion of working-age people will decrease, thus placing an even greater burden on young people to fund healthcare and pensions. The researchers – members of the Earth4All collective, made up of environmental scientists and economists – published their findings in a working paper on 27 March.

“We know that rapid economic development in low-income countries has a huge impact on birth rates,” said Per Espen Stoknes, director of the Centre for Sustainability at the Norwegian Business School and project lead for Earth4All, in a statement. “Birth rates fall as girls have access to education and women have economic opportunities, as well as better healthcare.”

The study is a follow-up to the Club of Rome's 1972 study 'The Limits to Growth', which warned the world of an impending 'demographic explosion'. The new results differ from other recent population forecasts. For example, in 2022, the United Nations estimated that the world's population would reach 9.7 billion by 2050 and grow to 10.4 billion by 2100. Ten years ago, UN estimates suggested that the population would reach 11 billion.

Other models predict population growth based on factors affecting women's social independence and physical autonomy, such as access to education and contraception. The Earth4All model is slightly more complex, as it incorporates variables related to the environment and the economy. These include energy abundance, inequality, food production, income levels, and the future impact of global warming.

The model predicted two possible future scenarios for human population development. In the first, a 'business as usual' case, where governments continue the current trajectory of inaction, creating ecologically unstable communities that are vulnerable to regional collapse, the population will rise to 9 billion people by 2050 and fall to 7.3 billion by 2100. The second, more optimistic scenario, under which governments invest in education, improving equality and an ecological transition, foresees that 8.5 billion people will live on the planet by mid-century, and 6 billion by 2100.

The team also studied the link between population and the planet's capacity to support human numbers. They found that, contrary to popular Malthusian narratives, population size is not the main driver of climate change. Instead, they blame the high levels of consumption of the world's wealthiest people, which they argue must be reduced.

“The main problem for humanity is carbon and biosphere consumption, not population size,” said Jorgen Randers, one of the modellers at the Norwegian Business School and a participant in the Earth4All organisation, in a statement. “Places where the population is growing the fastest have an extremely small environmental footprint per person compared to places that reached their peak population many decades ago.”

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