Why Reducing World Population Growth Is Still Critical


Population growth is a prime cause for many of the world’s problems.

More population growth means more consumption of the world’s resources. Large populations consume more energy, more fresh water, more fish from the ocean, more lumber from the forests. The energy reserves, water supplies, fish stocks and forests become depleted. Large populations expand into wilderness areas. The wilderness areas become destroyed. Large populations over-cultivate and over-herd the agricultural land they are living on. With time and overuse, the land loses its productivity; in ecologically fragile areas like the borderlands of deserts, overuse kills those marginal areas and turns them into deserts themselves. Larger populations drive more cars, use more electricity, and use more products that require a lot of energy to produce, such as chemicals and steel. More carbon dioxide is generated, the forests are destroyed, and global warming goes amok.

Population growth is also a fundamental cause of world poverty. The reason for this is somewhat technical. But sometimes, small subtle forces cascade into surprisingly dramatic effects.

Reducing population growth increases the percentage of people of working age relative to the percentage of people of non-working age. Having more workers and fewer non-workers in an economy makes that entire economy more productive. This increase in productivity from having an age structure that favors adults of working age is called a demographic dividend.

Before the onset of population control, a family in the Global South might have had four to five children. Call it 4 ½. After people choose to reduce their fertility, and modern contraceptive technologies become available, a typical family has two children. Family sizes of two children are typical of the Global North. This means that the average pre-population-control family will have two working adults and four and a half dependents. The average post-population-control family will have two working adults and two dependents, moving the population from only 31% working-age-productive to 50% working-age-productive. That is a significant change.

Now, technically, the previous paragraph slightly exaggerates the beneficial effect of reducing family size. It does not account for senior citizens. Countries in poor nations have a relatively small share people over the age of 65. High mortality rates kill people off over the life course. But more significantly, the vast supply of children “drowns out” the presence of the old people. As fertility reduction reduces the share of children in the population, the oldsters represent a larger and larger percentage of the population. Countries over the course of population reduction and fertility control undergo two phases. In the first phase, the percentage of children is reduced and there are big gains in economic growth. This produces better nutrition, better medical care and a healthier population. Fewer people die young and a larger share of the population lives to see old age. In the second phase, the percentage of the elderly increases in the population, often substantially. Economic growth declines as a result. Japan is experiencing this problem in a major way today. Europe is undergoing a milder manifestation of this issue. You don’t want too many diapers. You don’t want too many canes and walkers.

There are spin-off effects from this change in age structure that are equally beneficial. Here is a list from Marcio Cruz and Amer Ahmed of the most important extra benefits.

1. Increasing the percent of productive people in the economy raises the tax-base for the local government. This means more government services can be provided – including more anti-poverty programs.

2. Increased income divided among a smaller number of children means that each child can receive more education. That makes the labor force more productive simply from the increase in skill and personal abilities.

3. Increased production means increased savings. Those savings can be used to finance further capital investment.

4. The aging of the population also increases savings. People save more when they realistically think they are going to live long enough to need retirement funds. Those old-age savings can represent a significant contribution to the stock of national investment. Mason and Kinugasa provide strong statistical evidence that much of the economic success of Japan, South Korea and East Asia came from the extra investment monies that were associated with increased saving for retirement.

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Overall, the effects of population control on global poverty reduction are fairly strong. Cruz and Ahmed estimate that a 1% increase in the share of the working-age population is associated with a 1.6% increase in economic growth. This leads to a 0.3% reduction in the poverty rate. 0.3% may not sound like a lot to you. However, a 0.3% reduction in poverty can change a huge number of lives.

Take a country like the Democratic Republic of the Congo. The Congo has a population of roughly 90 million.  The World Bank estimates that 73% of the Congo is poor. That means the Congo has approximately 66 million poor people. Reduce that by 0.3%. That would pull two million people out of poverty. Saving two million people from poverty is a big, big, deal.

As I said before, most people don’t really talk about population control. Many people take it for granted. Much of the Global South is reducing its population spontaneously, as women choose to get more education and stay in the workplace, and as access to modern, effective forms of contraception improves. However, the demographic revolution is still incomplete. Fertility is still high in countries with very low standards of income, in countries with very low levels of government health services, countries with very strong traditional gender ideologies, and countries with a history of internal warfare. The United States has actually been quite constructive in helping nations set up programs of population control. In many countries, local public health officials and local economic development officials have taken the lead on this issue. There are countries, such as Thailand, where women’s access to reproductive services is excellent.

But more needs to be done. Reducing population reduces the number of people who have to live in slums and misery.

And if a smaller global population consumes fewer of the earth’s scarce resources, well, that isn’t such a bad thing either.

For More Information

The Cruz and Ahmed analysis of the effects of population reduction on poverty overall can be found in Marcio Cruz and Amer Ahmed. 2018. “On the Impact of Demographic Change on Economic Growth and Poverty.” World Development 105; 95-106.

The Mason and Kinugasa discussion of population reduction and increased savings in East Asia is famous. You can find that at Andrew Mason and Tomoso Kinugasa. 2008. “East Asian Economic Development: Two Demographic Dividends.” Journal of Asian Economics 19: 389-99.

On Thailand’s excellent medical services, see Joseph Harris’s first-rate book, Achieving Access: Professional Movements and the Politics of Health Universalism. (Cornell University Press, 2017)