Demographic Trends, explained
September 14, 2025
In this report, we are looking at population decline, ageing, urbanisation, and the consequences of these trends.
The Shrinking Population
Global population today: 8.2 billion people.
It is expected to peak at 10.4 billion around 2084 before starting to decrease.
Why? Declining fertility rate (average number of births per woman).
Why did global fertility decline?
Urbanisation led to increased costs of having children and changed social norms.
Increased access to education and work for women reduced focus on childbearing.
Increased access to and quality of healthcare decreased child mortality, reducing the need for many children.
Improved access to contraception, education and family planning changed preferences.
A fertility rate of 2.1 keeps the population size stable in the long term (replacement rate).
Global fertility rate peaked at 5.3 in 1963 and is around 2.4 today.
There are significant differences between world regions.
The Ageing Population
World’s (median) average age is expected to increase from 32 years now to 42 years by 2100.
Why? Growing life expectancy.
Global life expectancy was 73.3 years in 2024, compared to 60 years in 1980.
It is projected to rise to 78 years by 2050.
Life expectancy has increased because of (1) better survival at birth and during early childhood, and (2) better management of diseases in older ages.
In 1950, 65-year-olds had an average life expectancy of 11 more years; by 2025, it is 18 years.
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The Urban Population
Since around 2007, most people on the planet live in urban areas (cities).
By 2050, around 70% (7 billion people) would be living in urban areas.
The demographic transition is the trend for societies to shift from high to low birth rates as they develop economically.
This normally comes with greater investment in human capital (people) through education and other changes.
The “first wave” of transition includes countries with fertility rate of around 1.2 today and an ageing population.
This group includes Europe, North America, China, Japan and South Korea.
The “second wave” includes other countries in Asia, Central and South America, the Caribbean, the Middle East and Africa, with an average fertility rate above the replacement rate of 2.1.
It is expected to reach the current level of the first wave countries within 1-2 generations.
Second wave countries want to build wealth while their workforce is large as financing growth and welfare becomes harder with an ageing population.
Sub-Saharan Africa is an exception within the second wave due to its fertility rate of 4.4, expected to drop below 2.1 by 2100.
It has a population of 1.3 billion, projected to exceed 3 billion by 2100.
Many countries in the region have adopted policies to reduce fertility but often face challenges with their implementation.
Goal: to reduce pressure on limited resources like land, food and social services when the population is growing quickly already.
In the 1970s, China introduced the controversial one-child policy, limiting many families to 1 child.
China allowed 2 children per family in 2016, and then 3 children in 2021.
China's fertility rate decreased from 2.7 in 1979 to 1.8 but some of the decline had started earlier.
Families were choosing to have male children, so around 115 boys were born for every 100 girls during this period, creating societal imbalance.
The policy prevented around 400 million births.
The long-term issue: China's population is expected to age before the country becomes wealthy (on average).
It will face rising costs of sustaining a large ageing population with fewer workers.
The one child-policy worsened this problem as ageing parents have fewer children than their own parents had.
Dependency ratio is an important economic indicator.
It measures the proportion of working-age people (typically aged 15-65) to those younger and older.
Why it matters? In general, the labour force generates most of the country’s resources, including those needed to support children and elderly.
As the share of the labour force in the population falls, the economy may become less productive and social tensions can arise.
Global ratio of working-age individuals to non-working-age individuals is 1.8, expected to drop to 1.7 by 2050.
Migration
In general, people from high fertility countries are migrating to low fertility countries today.
Why? Destination countries seek to increase their workforce, while people from departure countries seek better economic opportunities.
Almost 4% of world population is made up of international migrants (304 million people in 2024).
Europe and North America are the main destinations for migration flows.
Europe hosts 94 million immigrants, the majority of whom came from other European countries.
The US hosts 52 million immigrants, mostly from South and Central America.
Global remittances (money sent back home by migrants) totalled $685 billion in 2024.
The largest recipients of remittances were India ($129 billion), Mexico ($68 billion) and China ($48 billion).
Climate Change
The country's wealth, more than its population size, is a determinant of its greenhouse gas emissions.
Why? Higher incomes lead to increased energy consumption, with fossil fuels accounting for approximately 82% of the world's energy production.
Comparison: The US has 4% of the global population and 13% of carbon dioxide emissions, while India has about 18% of the global population and 7% of the emissions.
An additional 2 billion people by 2084 will require an expansion of construction and agriculture.
Those sectors currently account for 37% and 11% of global greenhouse emissions, respectively.
The effect of population growth on climate change depends on the energy solutions adopted by countries:
If regions with expanding populations adopt greener energy solutions, then the impact of their development on emission levels will be moderate.
The energy solutions adopted by developed states also matter, especially if those countries continue to attract global migration flows.
Author Elia Preto Martini
Editor Anton Kutuzov
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