Weekend Reads | Population Growth

by Kevin Schofield

This weekend's read is a new report from the United Nations Department of Economic and Social Affairs predicting global population growth throughout the rest of this century.

The total population of our planet is expected to reach 8 billion this coming November. Since 1974 when we hit 5 billion, we've been adding another billion consistently every 11—13 years. Along with that came warnings of the dire consequences of uncontrolled population growth: a world that would not be able to fit all of its people, let alone feed, clothe, and shelter them.

All of that is changing. The latest UN prediction is that we will not reach 9 billion people until around 2040 — 18 years from now — and we will hit the 10-billion mark around 2060, 20 years after that. Shortly after that, the global population will peak at around 10.4 billion, and then start to decrease.

Now, it's fair to point out that these are modeling predictions, and there is a decent amount of variability in them: The population could continue growing to 12 billion by 2100, or shrink to below 9 billion. But the models aren't that complicated, and in fact, there are only a small handful of variables that control them.

One of those, of course, is life expectancy. In 2019 (pre-COVID), global life expectancy reached 72.8 years, a dramatic increase of about nine years from 1990. It is expected to continue to rise to about 77 years by the year 2050, as living conditions improve for people in low-income countries.

Another key variable is fertility rate: How many children does a person capable of childbearing have, on average, over the course of their life? In 1950, it was five births; last year, it had dropped to 2.3, and by 2050, it is expected to be around 2.1. This is heavily affected by income and education levels, but also more generally by health care standards and the control people are given over their own reproductive decisions.

But there is another factor that doesn't require guessing; it only requires mathematical modeling: how many people of childbearing age there are in the world. Because of historically low life expectancy in some of the most populous countries in the world, overall, the UN characterizes the global population as fairly youthful. But with life expectancy increasing, over time, the population as a whole will age and the percentage of people who can bear children will decrease. The UN predicts that by 2050, the number of people over age 65 will be more than twice the number of children under age 5 and about equal to the number under age 12. Combine that with the fact that life expectancy won't keep increasing forever — people will live longer, but eventually they still will die — and the population growth rate over the past few decades simply can't be sustained.

Now, while that's the picture at a global scale, there are huge differences when we look country by country, and that is likely to have significant geopolitical impacts in the years to come. For instance: China has for many years been the most populous country in the world, with India a close runner-up. But the effects of China's recently abandoned "one child" policy are now clear, and next year, India is expected to surpass China as the largest country.

In fact, the UN report predicts that more than half of the increase in global population over the next 30 years will be concentrated in eight countries: the Democratic Republic of the Congo, Egypt, Ethiopia, India, Nigeria, Pakistan, the Philippines, and the United Republic of Tanzania. At the same time, most higher-income countries have significantly lower fertility rates — several below the "replacement level" — and will reach their peak populations much sooner.

Some of these changes have already happened. According to the UN report, for high-income countries between 2000 and 2020, population growth was driven more by net migration from other countries (about 80.5 million people) than by an excess of births over deaths (about 66.2 million). In low-income countries, population growth is about births and deaths; in high-income countries, it's about people moving from other countries. The UN doesn't expect that to change in the coming years. Though in the short term, recent events can mask the extent of this effect: The war in Syria has driven a substantial amount of net migration in the Middle East and Europe, but on the other hand, COVID-19 lockdowns have severely restricted many migration patterns.

For those who worship at the feet of sustained economic growth, there will be dramatic change in the years ahead. In most of the world, economic growth is still driven by human labor; when the working population begins to shrink — as it already has in Japan, for example — the economy is likely to follow.

The UN Report is 50 pages of fascinating charts and discussion about both the "big picture" of global population growth and close-up views about how things will vary by country and region. The conventional wisdom about the global population is quickly being proven wrong, and as we get into the middle of this century, it will no doubt shake up the geopolitical world order.

World Population Prospects 2022: Summary of Results

Featured image by Arthimedes/Shutterstock.com.