Global population reaches 8 billion

Key takeaways:

• We expect the population to peak in about four decades, somewhere over 9 billion, and then begin to decline.
• In sub-Saharan Africa, fertility rates remain high, so the population will continue growing until the end of the century.
• In almost all other regions, the fertility rate is below replacement level. 
  • Lower fertility levels creates an inverted population pyramid, meaning a greater percentage of people in the population are older.
  • With more grandparents than grandchildren, there will be significant societal impacts that must be accounted for.
• Some options to address below-replacement fertility levels:
  • Increase support for parents through programs like subsidized childcare and enhanced parental leave.
  • Welcome migrants to solve the gap in workforce created by aging populations.

Read the research

This transcript has been lightly edited for clarity

November 15 is the day that the UN is celebrating the global population reaching 8 billion, and that has certainly occurred sometime this year, if not in the recent weeks. And the real question for us all is what does it mean and where is population going in the world? In our assessment at the Institute for Health Metrics and Evaluation, which is part of this new Global Health Insights, is that global population will peak in the 2060s, somewhere over 9 billion, and then begin to decline.

Continued growth in sub-Saharan Africa

But to understand population and its consequences, we need to look at the world in two groups. In sub-Saharan Africa, total fertility rates and the patterns of fertility in completed cohorts of women remain quite high. In parts of the Sahel, the total fertility rate is over seven. In other parts of East Africa and southern Africa, total fertility rates have declined substantially and some countries are below four, and we expect those declines to continue.

Declining fertility in the rest of the world

Nevertheless, those higher fertility rates in sub-Saharan Africa mean that we expect the population of sub-Saharan Africa to continue growing right toward the end of the century. That’s in sharp contrast to what we’re seeing everywhere outside of sub-Saharan Africa – with few exceptions. In places like China, the total fertility rate is now down as low as 1.1, with similar numbers in Japan, in Korea, in Taiwan, and in Singapore. We’ve seen India, the second largest country in the world, drop below replacement fertility in the past year.

So the pattern of below replacement fertility is now the norm outside of sub-Saharan Africa and in the course of the next generation will become essentially true in all countries, with few exceptions, outside of sub-Saharan Africa. This could be thought to be good for the planet – fewer people, less climate stress, but it comes with other consequences that societies are going to have to manage as fertility drops to these lower levels.

And we expect from our analysis that once women are educated and have access to pursuing careers and have access to reproductive health services, they tend to want to have about 1.4 children on average. Now, of course, there’ll be a lot of cultural variation in that, but it’s that average number that matters because 1.4, it means that with each generation, the population will get smaller.

Societal implications of an aging population

That creates an inverted population pyramid where there are more people in the age group ahead of you than behind you. This has all sorts of ramifications for how do governments balance the books? Who pays the taxes to pay for health insurance, social insurance? Elder care? How do economies work when it’s younger workers that tend to buy homes? So what will happen to the real estate market as populations go into decline?

And there’s faster decline in the younger age groups than in the older age groups. There will be societal impacts when there are more grandparents than grandchildren, and the knock-on effects are things that we don’t fully understand. And at least for the next 50 years, countries have two options in the set that have below-replacement fertility.

How to address it

One option is to support women and having children, the number of children they want to have as well as pursue careers. And that’s sort of the pattern that’s been used in northern Europe. Subsidized childcare, maternity leave, paternity leave, guaranteed rights to return to your job after pregnancy. That package of interventions and that can increase the fertility rate maybe by 0.1 or 0.2 children.

So that’s a benefit, but unlikely to bring you back to replacement in those societies. The other strategy, at least for the next 50 years, is to welcome migrants and you can solve your gap in the workforce. Keep the number of workers up and the tax base for societies up by having liberal immigration policies. And many countries will successfully pursue that.

Countries like Canada, Australia, and New Zealand have been pursuing that sort of immigration policy for decades, and they’ve managed to keep their population numbers and workforce up and/or actually increase them in some cases. Some countries are not very enthusiastic about bringing in migrants and yet have low fertility – China, Russia, many other countries. And they will face the biggest challenges, and we worry a lot in those settings that they will be tempted in some settings to roll back women’s reproductive health rights as a strategy to increase fertility.

And of course, that would not, in our view, be a good thing. It would be a setback for women. And so the global community really needs to be providing solutions for all countries about how to manage the challenges of low fertility. Are there strategies that reinforce women’s right to choose on their family size? Let them pursue careers that will also help reduce the sort of dramatic reductions in population size that are possible.

The impacts of climate change

In sub-Saharan Africa, it’s a different story, particularly in the Sahel region, where we expect they will be the first places in the world to face climate change impacts in the form of reduced agricultural input, heat stress in some settings in the Sahel. Some localities may not be habitable anymore as the number of days above some high threshold of temperature become intolerable.

So we do expect the combination of high fertility and climate stress in the next generation to likely lead to mass outmigration from some of those settings, either north across the Sahara or even more likely south from the Sahel belt into countries south of the of that belt. But some of those countries will also be facing the impacts of climate change. 

So the world needs a nuanced approach to thinking about population. The role of population forecasting and scenario building becomes important, especially as we learn more about the options available outside of Africa to increase fertility or promote migration. And within sub-Saharan Africa, the strategies are a little bit more clear. Get women access to contraception and reproductive health services, as well as enhance the education of women, which remains really quite low in some parts of the Sahel particularly. Expect more in our Global Health Insights in the future as we try to take the modeling here at IHME – the forecasting, the scenario building, and look at some of the other threats to human health and prosperity around the world in the coming editions of the Insights.