READ: Data Exploration – Future Population Growth

There are a lot of us on this planet—more than ever. We can make educated guesses about how many people there were in the past and how many people there will be in the future, but the further we go in either direction, the less sure we are. While our population continues to increase, the rate of that increase started to slow down in the 1960s. Populations in some parts of the world are shrinking, while in others they are rising. Predicting the future of these trends is incredibly important to the future of our planet and societies. Can data help us?

The data exploration article below uses “Three Close Reads”. If you want to learn more about this strategy, click here.

First read: preview – what do we have?

This will be your quickest read. It should help you get the general idea of what this chart is about and the information it contains. Pay attention to:

Labels and titles. What is the title? How are the axes labeled? Is anything else on the chart labeled?
Data representation. How many variables are there and what are they? What are the scales? What time period does the chart cover? Is the chart interactive?
Data source. Where did the data for this chart come from? Do you trust it? Who created the chart?

Second read: key ideas – what do we know?

In this read, you will pay attention to the information that most helps you understand the chart and the information it is trying to convey. Pay attention to:

Claim(s). What can you say about the data? What story does it tell? Can you make any claims about this data? Does it change when you zoom in compared to when you look at the data as a whole?
Evidence. What data from the chart supports this story? Does this change if you change the scale or variables?
Presentation. How does the way this chart is presented influence how you read it? Has the author selected certain variables or scales that change the conclusions that can be drawn? Is there anything missing from this chart?

By the end of the second read, you should be able to answer the following questions:

According to Chart 1 and 2, when did the global population increase at the highest rate?
According to Chart 1, if we lower the global growth rate of the human population over the next century, will the global population decline?
Why do you think the makers of Chart 1 believe that the global population will continue to grow even if we slow the rate of growth? Do you agree?
According to Chart 2, in what regions has the population growth rate decreased the most since 1950? Where has it increased the most?
On Chart 2, if you select the Chart button at the bottom, you can see population growth rates as a line graph for individual countries and regions. Try comparing Africa and Europe. What do you notice? Do you agree with the predictions in the chart?
According to Chart 3, which three countries had the largest population in 2015? Which will have the largest populations by the year 2100? When compared with the information in Chart 2 on population growth rates, what does this tell you about the relationship between total population and population growth rates?
Do you trust the predictions in these charts? Do you think we can reliably predict what populations will look like in 100 years using data about the past? Why or why not?

Third read: making connections – what does this tell us?

The third reading is really about why the chart is important and what it can tell us about the past and help us think about the future. Pay attention to:

Significance. Why does this matter? Does this impact me, and if so, how? How does it connect what is going on in the world right now? How does it relate to what was happening at the time it was created?
Back to the future. How does this data compare to today? Based on what you now know, what are your thoughts on this phenomenon 25 years, 50 years, and 100 years from now?

At the end of the third read, you should be able to respond to these questions:

Why does this chart matter? What do these charts tell us about the future of human communities? What do they tell us about how we produce and consume resources? Can population predictions help us understand anything about global inequality in the future?
Using these charts and a chart from a previous data exploration, make a new prediction about how human communities will change in your lifetime. What evidence from the charts supports your prediction? What evidence challenges it?

Now that you know what to look for, it’s time to read! Remember to return to these questions once you’ve finished reading.

Future Population Growth Data Introduction

By Max Roser, adapted by Mike Papritz and Eman M. Elshaikh

There are a lot of us living on this planet. But the rate of population growth has slowed in recent decades. Can data help us predict our population future?

Population growth—past, present, and future

Over the course of the last school year, you’ve probably noticed something about population on this planet: there are more of us here than there used to be. We know approximately how many people inhabit this planet today (around 7.7 billion in 2019). We have reasonably good estimates for the recent past (2 billion in 1928; 1 billion in 1803). But the further back we go, the murkier the data gets. The same is true for the future—the further we travel forward in time, the less certain we can be about how many people there will be on Earth.

For much of human history, the global population was much smaller than it currently is, and it grew at a relatively slow rate. But during the twentieth century, our global population quadrupled. Since then, population growth appears to be slowing down. Though our overall population has continued to rise, the rate of its increase started to decline in the 1960s. Today, the global population grows by about 1 percent each year. You can see these trends illustrated in Chart 1.

Chart 1:

Will these trends continue? That’s a really important question. Population affects things like available space and resources, which are increasingly limited. The more people there are on Earth, the more food, fuel, space, and materials are needed to sustain them. Think of it this way: The number of people keeps changing, but the planet and the resources on it are a lot more fixed. That’s a problem.

That’s part of the story. But there’s more to it. Humans aren’t just stomachs—they’re also brains. As our population has grown, so has the pace of innovation in technologies and institutions that have allowed us to use our limited resources in new problem-solving ways. Our recent past has shown that more people can mean more food, new fuels, and more useful innovations. We just might be more brain than stomach.

Predicting the future with data

Whether you think population growth is a problem for the future or might provide solutions to our most pressing problems, it will be central to our future as a species on this planet. Scholars have spent a lot of time trying to predict what our population will look like in the next century. To understand where we might be headed, we need to know where we’ve been.

As one example, explore the two maps below. Map 1 shows past data (1950–2015) about population growth rate by country. Map 2 uses past data, like that in Map 1, to make predictions about the future (2015–2100) of population growth by country. Note: While exploring these maps, you might see the phrase “medium variant” pop up. Don’t worry too much about what it means—just think of it as the most likely scenario.

Map 1:

Map 2:

By exploring these two maps as well as Chart 1, you can see that there are past trends that scholars use to predict the future of the global population. The twentieth century saw huge increases in both our population and the rate at which it grew. More recently, the global rate of growth has started to slow, and we expect that trend to continue. But by switching scales, we see dramatic differences in the rates of population growth. While Eastern Europe has seen its population shrink in recent years, many countries in Sub-Saharan Africa are experiencing higher than average growth rates. But why has any of this happened? What causes the population size to change?

Three drivers of population growth

There are three main factors that affect population growth in a country or region: mortality, fertility, and migration. Just so we’re on the same page, let’s define them:

Mortality: Death rates across a country, region, or globally.
Fertility: The average number of children born per women.
Migration: Migration into (immigration) or migration out of (emigration) a region/country.

Globally, mortality rates have decreased. Child mortality in particular has declined. Life expectancy has increased across the globe. Declining mortality rates have made the population grow. That explains everything, right? The population is growing because people are dying less.

Well, not quite. Remember that while the population is indeed growing, the rate of growth is slowing down. That’s partly because although mortality rates have dropped, fertility rates have also gone down. On average, women are having fewer children. That reduces population growth rates. The global average fertility rate was 5 children per woman until the end of the 1960s. Since then, it has been cut in half, with an average of 2.5 children per woman. Fertility is a variable factor. It can change depending on how a society develops culturally and economically. Fertility is particularly dependent on the well-being and social status of women.

So, we have a few different variables that affect population growth: how big a population is to begin with, death rates (mortality), and birth rates (fertility). At the global level, population changes are determined by the balance of only two variables: the number of people born each year, and the number who die. But at the national or regional level, we need to consider a third variable: migration.

We can consider these variables when trying to understand past population changes and project future population changes. But when we’re trying to make projections about the future, there are a few different ways we can do that.

Future projections are really complicated, even for experts. But for our purposes, it really comes down to whether we think the future will be like the past or not. Are different regions experiencing the same, or different, trends? What will happen to the human population in the future, and what will that mean for the world? You will have the opportunity to explore these questions—and come to your own conclusions—in this data exploration.

Author bio

Max is the founder and director of Our World in Data. He began the project in 2011 and for several years was the sole author, until receiving funding for the formation of a team. Max’s research focuses on poverty, global health, and the distribution of incomes. He is also Programme Director of the Oxford Martin Programme on Global Development at the University of Oxford, and Co-executive Director of Global Change Data Lab, the non-profit organization that publishes and maintains the website and the data tools that make OWID’s work possible.

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Rose Adams
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