<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
You are reading an older version of this FlexBook® textbook: CK-12 Earth Science Concepts For High School Go to the latest version.

# 13.1: Growth of Human Populations

Difficulty Level: At Grade Created by: CK-12
Estimated3 minsto complete
%
Progress
Practice Growth of Human Populations
Progress
Estimated3 minsto complete
%

What will stop population growth?

It took all of human history until 1802 for the human population to reach its first billion. It took just 12 years for it to acquire its most recent billion. Although the growth rate is predicted to slow later this century, there's no end to population growth in sight. Yet, the population can't continue to grow forever. How will it stop?

#### Human Population Numbers

Human population growth over the past 10,000 years has been tremendous ( Figure below ). The entire human population was estimated to be

• 5 million in 8000 B.C.
• 300 million in A.D. 1
• 1 billion in 1802
• 3 billion in 1961
• 7 billion in 2011

As the human population continues to grow, different factors limit population in different parts of the world. What might be a limiting factor for human population in a particular location? Space, clean air, clean water, and food to feed everyone are limiting in some locations.

Human population from 10,000 BC through 2000 AD, showing the exponential increase in human population that has occurred in the last few centuries.

An interactive map of where human population growth has been over time: http://www.pbs.org/wgbh/nova/worldbalance/numbers.html .

#### The Rate of Growth

Not only has the population increased, but the rate of population growth has increased ( Figure below ). The population was estimated to reach 7 billion in 2012, but it did so in 2011, just 12 years after reaching 6 billion.

The amount of time between the addition of each one billion people to the planet’s population, including speculation about the future.

Although population continues to grow rapidly, the rate that the growth rate is increasing has declined. Still, a recent estimate by the United Nations estimates that 10.1 billion people will be sharing this planet by the end of the century. The total added will be about 3 billion people, which is more than were even in existence as recently as 1960.

### Summary

• The human population is growing more than exponentially.
• The human population is increasing, the rate of human population growth is increasing, but the rate at which the rate of growth is increasing has declined.
• The United Nations estimates a population of 10.1 billion by the end of the century yet that is much less than the number we would expect if 1 billion people were being added every 12 years.

### Practice

Use this resource to answer the questions that follow.

1. What was the population in 1800?

2. What was the population in 1930?

3. What could the population be in 2045?

4. What is the average lifespan of people today?

5. What was the average lifespan of people in 1960?

6. What is a megacity?

7. How many megacities were there in 1975?

8. How many megacities are there now?

9. Explain what the world needs.

10. How much of the population lacks adequate sanitation?

### Review

1. What does it mean that the human population growth rate is increasing?

2. What does it mean that the rate that the growth rate is increasing has declined?

3. What factors may someday limit human population growth?

Feb 24, 2012

Jan 30, 2016