Evolution of the world population
The changing world population and its impact on the future of the planet
A study published in 2020 by the prestigious journal 'The Lancet' directly contradicted the forecasts being made by the United Nations (UN) about the future population of the world. At the time, the UN was predicting that there would be 11.2 billion people on the planet by the year 2100. 'The Lancet', meanwhile, reasoned that the global population would peak in 2060 and then fall to 8.8 billion by 2100 thanks to improvements in education for women and better access to contraception.
Four years later, and the UN has revised its projections and has partly come around to The Lancet’s estimations. In its report World Population Prospects 2024, which was published in July of that year, the UN predicted that the world’s population would peak in the mid-2080s. According to these new projections, the global population is expected to grow from the 8.2 billion recorded in 2024 to around 10.3 billion by the mid-2080s, followed by a slight decline to 10.2 billion by 2100. Just a decade ago, the UN projected that by the end of the century, there would be 700 million more people than now.
Historical growth of the world population
Before we examine current trends and projections for population growth, it is worth considering its causes. The world’s population has grown by more than three times since the mid-20th century, from an estimated 2.5 billion people in 1950 to the current 8.2 billion. But history shows that the evolution of the world's population has not always followed this current dizzying pace. In particular, two historical moments marked this evolution of the global population:
- On one hand, the Neolithic Revolution, which took place between 10,000 and 8,000 BC, marked a decisive shift in human history. During this period, humans began mastering agriculture and animal domestication, which enabled the settling of communities and freed up labour for activities such as craftsmanship. These advancements spurred significant population growth, raising the global population to approximately 300 million people.
- On the other hand, the Industrial Revolution (1760–1840) triggered an unprecedented population boom. During the 19th century, innovations such as steel manufacturing, mass production, assembly lines and electrical networks transformed economies and societies. As a result, the global population doubled during that century and tripled in the 20th century, reaching six billion people by the year 2000. This exponential growth was driven by medical, scientific, and economic advancements that improved living conditions and reduced mortality rates.
In 2011, the world's population reached a new milestone of seven billion people, and then just 11 years later the UN designated 15 November, 2022 as the approximate day when the figure reached eight billion. As of 2024, the world’s population stood at 8.2 billion according to the UN.
Causes of population growth
World population growth is marked by three factors, according to the UN:
Fertility rates
Population growth largely depends on trends in fertility rates. Currently, the global average is 2.3 children per woman, but this figure is expected to decline to 2.1 by 2050, according to the UN's World Population Prospects 2024 report.
Increase in longevity
Life expectancy, which saw a decline in 2020 and 2021 due to the COVID-19 pandemic, has returned to pre-pandemic levels since 2022. Currently, global life expectancy at birth is 73.3 years and is projected to reach 77.4 years by 2054, according to UN forecasts.
International migration
Although international migration has a smaller impact on global population change compared to the factors mentioned earlier, it can be significant in certain regions. For instance, in countries that receive economic migrants or are affected by refugee flows, migration plays an important role. What’s more, in countries such as Germany, Japan and Italy, net immigration helps offset population decline, delaying the point at which it would have peaked.
Projections and trends in the world population
Having established the causes of world population growth, here are some of the projections and trends according to the United Nations.
A peak is approaching. The UN projects that the global population will continue to grow over the next 50 to 60 years, reaching a peak of approximately 10.3 billion people by the mid-2080s. This would represent an increase from the 8.2 billion recorded in 2024. However, it is estimated that by the end of the century, the global population will slightly decline, settling at around 10.2 billion.
In 63 countries and regions, which account for 28% of the world's population, the number of inhabitants has already peaked, according to UN data. Among these countries are China, Germany, Japan and the Russian Federation.
Global fertility rates have fallen. The global fertility rate has experienced a significant decline in recent decades, dropping from 3.3 births per woman in 1990 to 2.3 in 2024. Furthermore, more than half of the world's countries and regions now have fertility rates below 2.1 births per woman. This is the threshold required for a population to maintain its size in the long term, excluding migration.
Life expectancy is on the rise. Global life expectancy has shown steady growth over recent decades. In 1995, it was 64.9 years, rising to 73.3 years in 2024. This figure is projected to increase to 77.4 years by 2054. Although the COVID-19 pandemic caused a decline in life expectancy during 2020 and 2021, it has since recovered to pre-crisis levels.
The future of the most populous countries in the world. India became the world's most populous country in 2023, surpassing China. According to UN estimates, India's population will continue to grow for several decades, exceeding 1.5 billion people by the year 2100. In contrast, China has already reached its population peak and has been experiencing a decline since 2022. It is projected that China's population will fall to 771 million by the end of the century.
The influence of immigration. The movement of peoples from one country to another is expected to be the main driver of future growth in 62 nations from here to 2100, according to the UN’s forecasts. These include Australia, Canada and the United States. Immigration will compensate for falling populations in many territories, as caused by low fertility levels and an ageing population.
An ageing population. The UN projects that by the end of the 2070s, the number of people aged 65 and over will surpass the number of those under 18. This demographic shift will be driven by the continued increase in life expectancy and the reduction in mortality rates observed since the 2010s. This underscores the impact of population aging on future social and economic structures.
Consequences of population growth
Global population growth has positive aspects for the development of society, but it also has negative effects on the planet, putting strains on resources such as food, water and energy, as well as increasing pollution levels and deforestation. Here are some of the most important consequences.
Climate change
Climate change refers to the alteration of the climate, whether directly or indirectly attributable to human activity. This means that the larger the human population, the greater the impact on the environment. A key factor in this process is greenhouse gases, which accumulate in the atmosphere, trapping heat and amplifying the greenhouse effect. This contributes to the rise in global average temperatures. As a result, extreme weather events are becoming more frequent, including heatwaves, hurricanes and floods. These events not only cause population displacement and material damage but also lead to an increase in injuries and deaths related to cardiovascular and respiratory diseases.
Decreased food security
According to the Food and Agriculture Organization (FAO) of the United Nations, food security is defined as a situation where all people have consistent physical, social and economic access to safe, nutritious and sufficient food to meet their nutritional needs. The population explosion puts pressure on the fundamental pillars of food security: availability, stability, access and consumption. This results in significant challenges in ensuring that everyone can access adequate food. A report published in July 2024 by five UN agencies revealed that 733 million people suffered from hunger in 2023. This figure represents one in every 11 people globally and one in every five in Africa, highlighting the severity of the issue in particularly vulnerable regions.
Impact on biodiversity loss
Biodiversity loss refers to the decline or disappearance of the variety of living organisms on the planet, ranging from microorganisms to entire ecosystems. This phenomenon is exacerbated by population growth, which increases human activity and expands the presence of artificial elements at the expense of natural environments – a hallmark of the Anthropocene era. According to the Living Planet Report 2024 by the World Wide Fund for Nature (WWF), global wildlife populations have experienced an average decline of 73% between 1970 and 2020, in just 50 years. This alarming decrease highlights the impact of human activities on ecosystems and the urgent need for action to protect biodiversity.
Overexploitation of resources
According to the United Nations, population growth, along with urbanization and industrialization, is driving a significant increase in the demand for natural resources. UN projections indicate that global consumption of these resources will grow by 60% between 2020 and 2060. This scenario poses an imminent risk of a resource crisis, which could intensify in the coming decades if urgent measures are not adopted. The warning underscores the need to implement sustainable strategies to manage resources more efficiently and mitigate the effects of overconsumption.