This week, the United Nations Population Division released new projections for the world’s population. Since they were last done in 2008, the UN’s projections have been revised upwards: fertility rates are just not falling as fast as earlier predicted. The new report says that by 2050, the world will mostly likely have 9.3 billion people, up from around seven billion this year. This is an increase of 156 million people over the UN’s last estimate for global population in 2050.
Projecting population trends out to 2050 has some measure of certainty because everyone who will be forty years old in 2050 is already born. But the report also projects population out to 2100, which has much greater uncertainty. Even small variations in fertility can lead to big changes. The UN’s medium variant (the “best guess” of demographers) has global population reaching 10.1 billion in 2100. But the high variation (which assumes fertility of just half a child more than the medium variant) projects a figure of 15.8 billion. The low variant (which assumes fertility of just half a child below the medium variant) has population peaking at 8.1 billion in 2045 and then declining to under 6.2 billion by the end of the century. The difference between the high and low variants in 2100—more than 9.6 billion people—is almost 40 percent greater than the world’s total population today.
Fertility rates, more than any other factor, determine global demographics. Today, 82 percent of the world’s population lives in either low-fertility (below replacement level) or intermediate-fertility (at replacement level) countries; 18 percent lives in high-fertility countries. The fifty-five countries in the latter category, despite having a small share of today’s global population, will account for a huge share of demographic growth in the coming decades. According to the UN’s medium variant, the population of high-fertility countries will more than triple by the year 2100. The population of intermediate-fertility countries is projected to grow by 26 percent, while low-fertility countries’ population is projected to decline by 20 percent.
Countries with high fertility are overwhelmingly concentrated in Africa and Asia, and the projections for some of these countries are staggering. The medium variant projects Malawi’s population to skyrocket from around 15 million today to more than 129 million in 2100. Nigeria, already Africa’s most populous country at 158 million people, is projected to have just under 730 million by the end of the century. Yemen’s population is projected to quadruple from 24 million today to 99 million in 2100.
These trends are troubling in many ways. As my colleague Gayle Tzemach Lemmon and I write in a recent CFR report, “Family Planning and U.S. Foreign Policy,” young and expanding populations can be sources of dynamism and economic growth. But many high-fertility countries today lack the capacity to reap these demographic dividends. This can lead to entrenched poverty, greater potential for conflict, and environmental strain. Investing more in family planning is one cost-effective way to help men and women make their own choices about the number and spacing of their births. Today, hundreds of millions of women in high-fertility countries want to delay or avoid pregnancy but do not have access to modern contraceptives to make that possible.
Also interesting is what the UN projections have to say about Asia’s emerging giants, China and India. Currently trailing China by more than 100 million people, India is projected to overtake its neighbor by 2025, according to the medium variant. Indeed, China’s population is projected to peak around that same year and, thereafter, to experience an eye-popping decline. By 2100, China will have 400 million fewer people than it does today—a reduction larger than the entire current U.S. population. India’s population is also set to peak during this century, but the country will remain substantially more populous in 2100 than it is today. Overall India is projected to have 1.55 billion people in 2100 and China 941 million.
Chinese leaders are certainly aware of their country’s demographic prospects; there is talk in Beijing of relaxing the one-child policy, perhaps to allow two children instead. It is an open question, though, whether such a change would result in higher fertility. As an article in this week’s Economist notes, even today the one-child policy “hardly applies to China’s minorities and is more lightly applied in rural areas—and there is no population boom in those parts.”
As for the United States, the UN’s medium variant projects a population of 478 million in 2100, an increase of more than 50 percent from the current total. The United States is essentially alone among large developed economies in its forecast for continued population growth. This is due to slightly higher fertility and immigration.
Putting all these projections together paints a picture of a world in 2100 that is profoundly different from today. For example, China today is more than four times as populous as the United States. But by 2100, according to the medium variant, China’s population will be less than twice as big as America’s. India will dwarf all other countries in population, and countries such as Nigeria, Pakistan, and the Democratic Republic of the Congo will be serious population heavyweights. Demography is not destiny, but the UN projections hold important implications for economic growth, security, and leadership in the twenty-first century.