Population Growth and Decline » World Population Growth

Slow growth, then the population explosion

For most of human history, the world's population grew very slowly. It reached about 1 billion around 1800. Then growth sped up. The jump after 1950 is often called the population explosion. The world total is now over 8 billion.

Key terms:

• Population growth: the increase in the number of people living in an area.
• Population explosion: the very rapid rise in world population since about 1950.
• Growth rate: how fast a population is growing, shown as a percentage per year.
• Projection: an estimate of future numbers, based on current trends.

The table shows how the time taken to add each extra billion people fell. The dates are approximate and come from United Nations estimates.

World population	Approximate year reached	Years taken to add this billion
1 billion	1800	Many thousands of years
2 billion	1927	about 123
3 billion	1960	about 33
4 billion	1974	about 14
5 billion	1987	about 13
6 billion	1999	about 12
7 billion	2011	about 12
8 billion	2022	about 11

The first billion took thousands of years. The most recent billion took only about a dozen. On a graph, the line is almost flat for most of history. It steepens sharply after about 1800 and especially after 1950, and it is still steep today.

The growth rate is slowing

This part surprises many students. The total population is still going up, but the growth rate has been falling since the 1960s. In the 1960s the world grew by more than 2% a year. Today it is about 1% a year.

Think of a car on a motorway. It is still moving forwards, but it is slowing down.

Projections: the future as a range

The United Nations (UN) makes projections of future population. They are given as a range, not one number, because nobody knows for certain how people's choices will change. The UN's middle projection is that world population will peak at about 10 billion in the 2080s and then level off or fall slightly. Higher and lower projections sit either side of this. Treat every projection as an estimate, not a fact.

Where is growth fastest, and where is it stable or falling?

Growth is not the same everywhere. The pattern is very uneven.

Pattern	Where
Fastest growth today	Sub-Saharan Africa, and parts of South Asia. Many of these countries are LICs.
Stable or falling	Europe and East Asia. Japan's population has been falling for years, and China's total began to fall in 2022.

Because of this, a large share of the extra people in the next few decades will be added in sub-Saharan Africa and South Asia. The reasons for growth and decline in a country are covered in the lesson Why Populations Grow and Shrink.

How to describe a population graph

Graph questions ask you to describe. Do not explain why. Use this order:

1. Trend: say the overall direction, such as rising, falling or levelling off.
2. Rate: say whether it is changing slowly or quickly, and whether that speeds up or slows down.
3. Figures: quote numbers with units from the graph, such as years and millions.
4. Anomalies: point out anything that does not fit the pattern, such as a sudden dip.

Exam-style question

Fig. 1.1 shows the population of Country M, a made-up country.

Year	1950	1970	1990	2010	2030 (projection)
Population (millions)	20	31	48	60	66

Fig. 1.1

(a) Calculate the increase in population between 1950 and 2010. [1 mark]

(b) Describe how the population of Country M changes between 1950 and 2030. [3 marks]

(c) Suggest why the UN gives projections as a range rather than one number. [2 marks]

(d) Describe the pattern of world population growth since 1800, and where it is fastest today. [6 marks]