The Demographic Tsunami

According to most estimates, the human population passed 8 billion in late 2022. Now is a good time to talk about the human population and how it is changing. It has not just increased in size; it has also changed in composition.

Since about 1970, the population has been growing linearly, increasing by 1 billion every 12 years. Linear growth is unusual in nature. Populations normally grow exponentially until they approach a limit. This linear growth seems to be a fluke. During that period, the world had declining fertility, but the population was increasing. The result just happened to be roughly linear growth.

Population growth has not been evenly distributed across countries. Some countries, such as Nigeria and Pakistan, grew very rapidly, while others grew more slowly. A few, such as Russia and Japan, now have declining populations, due to prolonged low fertility. Others, such as China, are still growing, but have below-replacement fertility and are projected to begin declining soon.

China and India are the biggest countries in the world, by far. Both have over 1.4 billion people. The United States is a distant third, with about 332 million people. (That number could be an underestimate, due to illegal immigration.)

The world has changed a lot in recent history. Most people aren’t aware of how much it has changed. In 1970, the global population was less than half of what it is today. China and India were the biggest countries then, as they are now, but they were proportionately closer to the United States than they are today. The third biggest country was the Soviet Union, with about 240 million people. However, the Russian part of the Soviet Union was significantly smaller than the United States. Of existing countries, the United States was third, and Russia was fourth. Indonesia was fifth, at less than half its current size. Japan was sixth, with 103 million. The other countries were Brazil, Germany, Bangladesh and Pakistan, all with populations below 100 million. By 2021, Japan and Germany had dropped out of the top 10, replaced by Mexico and Nigeria.

The following table shows the top 10 countries in 2021 by population, their populations in 2021 and 1970, and the ratio between those populations. Nigeria and Pakistan had the biggest proportional increases. Both were almost four times bigger in 2021 than in 1970. India, Indonesia, Bangladesh, Mexico and Brazil more than doubled. The United States increased by 62% and China increased by 73%. Russia had the lowest proportional growth, increasing by only about 10%.

Country 2021 Population
1970 Population
United States331.9205.11.6

The following chart shows how the world population is distributed across the major geographical regions. East Asia & Pacific is the largest region, followed by South Asia. Together, they contain more than half the world’s population. North and South America together contain only about 13% of the world’s population.

Demographically, the world is a very different place today than it was in 1970. All regions grew, but some regions grew much more than others, proportionately.

Differences in fertility were the main reason for the differences in population growth between regions and countries. The following chart shows fertility (children per woman) by region, over the period 1970 to 2020. As you can see, there was a general decline in fertility, but the decline differed significantly between regions. Also, some regions started with much higher fertility than others. Even without immigration, a population can continue to grow for decades after fertility has fallen below replacement, due to demographic momentum.

The following chart shows the population of children (aged 0 to 14) by region, in 2021. Compare this chart to the current population by region to get an idea of how the world is changing demographically. East Asia & Pacific has the largest population currently, but South Asia has the largest child population, followed closely by Sub-Saharan Africa.

The following chart shows the top 10 countries by child population. It is significantly different from the top 10 countries by total population. India has many more children than China. Instead of being third, the United States is sixth, after Nigeria, Pakistan and Indonesia. Ethiopia is next on the list, even though it is not in the top 10 by total population. Congo D. R. also makes it onto the list.

The next chart shows the child population for selected countries. It shows how countries that were very important in the past, such as France, Germany, Russia, Japan and the United Kingdom, are fading into global insignificance demographically. Nigeria alone has more children than all of those countries together. So does Pakistan.

High fertility countries, such as Nigeria and Pakistan, have rapidly growing child populations. Countries with low fertility and low immigration, such as Russia and Japan, have declining child populations. In the United States, the child population has been roughly steady, despite an increasing population due to immigration. The same is true of the United Kingdom. It has roughly the same child population as it did in the 1960s.

Most people know that the human population has grown significantly in the past half century, but few appreciate how much the composition of the population has changed. Many people are shocked to discover that Nigeria has a bigger population than Russia. The composition of the world is changing geographically, racially and culturally.

These demographic changes will have a big impact on the future of the world. As the global population increases, and fossil fuels are burned up, life will get harder. The hardship will be worst in the more populous and less-developed parts of the world. There is likely to be mass migration from those regions into the richer parts of the world, especially Europe.

In the past, the developed world, and especially the West, could bail out less-developed countries during hard times. For example, Western countries sent a large amount of aid to Ethiopia in 1985, to help deal with famine conditions. At the time, Ethiopia had about 40 million people. Today, it has over 120 million. It would be much harder for the West to help Ethiopia today. The same is true for many countries, such as Pakistan, that are economically fragile and have huge populations. If they collapse, it will be hard for the West to bail them out or absorb the refugees.

The future is determined by who shows up. The population explosion in the less-developed parts of the world is a demographic tsunami that will sweep over the world and profoundly change it.


World Bank, Total Population

World Bank, Fertility Rate

World Bank, Under 15 Population