The Most Populous Countries in 2100

In 2017, the United Nations Population Division released its World Population Prospects: The 2017 Revision, a set of population projections out to the year 2100 for the planet Earth and for individual countries. The United Nations expects the global population— 7.6 billion as of 2017—to reach 11.2 billion by the year 2100. The report placed current population growth at 83 million people per year.

The United Nations looked at population growth both globally and at the country level. Of the 10 largest countries, Nigeria is growing the fastest and is expected to have a population of nearly 800 million by 2100, making it even larger than the United States. By 2100, the U.N. predicts that only India and China will be larger than Nigeria.

The Most Populous Countries in 2100

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Predicting the 20 Most Populous Countries in 2050

By Matt Rosenberg

Current population growth varies wildly from country to country, and the list of the most populous nations in the world is expected to look much different by the turn of the next century.

These U.N. projections are based on national censuses and survey data from around the world. They were compiled by the Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. The full data is available for download in a customized Excel spreadsheet.

Compared to current population estimates and 2050 population projections, note the high number of African countries on this list (five out of the top 10). While population growth rates are expected to decline in most countries in the world, African countries by 2100 may not experience much reduction in population growth at all. Even some countries whose growth rates are expected to decline will still become much larger, as their growth rates are already relatively high. Most notably, Nigeria is expected to become the third most populous country in the world, a spot long held by the United States of America. Of the five most populous nations in 2100, five are expected to be African countries.

About half of the world's population growth over the next 30 years is expected to take place in only nine countries: India, Nigeria, the Congo, Pakistan, Ethiopia, Tanzania, the United States, Uganda, and Indonesia.

Reasons for Population Growth

In developed nations around the world—including England, France, and Japan—fertility rates are declining, reducing overall population growth. However, some of the decline in growth is being mitigated by longer life expectancies, which have risen to 69 years for men and 73 years for women. The global increase in life expectancies is due to multiple factors, including a reduction in child mortality rates and improved treatment for HIV/AIDS and other diseases.

In most developed nations, populations are expected to see minimal or negative growth over the next century. Diminished fertility rates will result in aging populations, with people over the age of 60 making up about 35 percent of Europe's population (they currently make up only 25 percent). Meanwhile, the number of people over the age of 80 is expected to increase as well. By 2100, the U.N. predicts there will be about 900 million people in this age cohort around the globe, nearly seven times as many as there are now.

Another reason for shifting populations, the U.N. notes, is migration, and the Syrian refugee crisis, in particular, is expected to substantially increase the populations of Syria's neighbors, including Turkey, Jordan, and Lebanon. Migration is also expected to take place in other parts of the globe, much of it driven by the effects of climate change. As rising temperatures disrupt ecosystems and increase food insecurity, more and more populations will be displaced, causing demographic changes in affected areas. A 2018 report by the World Bank found that worsening climate change could cause more than 140 million people to become "climate migrants" by 2050.