Grade 9-12

Population Growth: Friend or Foe?

Updated: August 9 2019,
Author: Melanie Marks

The environment has recently been the focus of much research and discussion. Because productive resources are limited, it is important that we use resources wisely to ensure that resources will be available for use in future generations. Of concern to both environmentalists and economists are the trends in the world’s population
[Note to Teachers:  Not all students may feel comfortable discussing some of the consequences of China’s “one-child” policy addressed in Task 6.]


The environment has recently been the focus of much research and discussion.  Because productive resources are limited, it is important that we use resources wisely to ensure that resources will be available for use in future generations.  Of concern to both environmentalists and economists are the trends in the

See this related article: “World Population: A Major Issue for the Millennium

crowdOf primary importance is the population growth rate.  The population growth rate measures the percentage increase in a population.*  For example, if the population growth rate for a given country is 1.2, then population in that country has increased by 1.2%.  Of course, the population growth rate could be negative.  A growth rate of -.01, for example, would mean that the population has decreased by .01%.

If the population growth rate is rising over time, then the size of the population is growing at an increasing rate.  For example, in 1960 the world population was at 3,039,451,000.  In 1961 56,010,616 people were added to the planet (a 1.8% increase); in 1962 69,397,019 were added to the planet (a 2.19% increase.)  The rising rate means not only that population is increasing, but that it is increasing at a faster and faster pace.

Learning Objectives

  • Calculate population growth rates.
  • Use Bureau of Census data to find statistics on specific countries.
  • Compare the population situation in More Developed Countries (MDCs) to that of Lesser Developed Countries (LDCs).
  • Calculate how long it will take a country’s population to double.
  • Discuss the idea of using government policy to control population.

Resource List


Identifying the Trends

In order to learn about the trends in world population for the years 1950-1998, you can access data made available on the .  Use the data to answer the following questions.

Question 1   

  1. Discuss some of the general trends you observe for the years between 1950 and 1998.
  2. What trends are forecast for 1999-2050?

[Note to teachers: You will get answers showing that growth rates increased for some periods and decreased for others.  During the 1950s and 1960s we saw increases.  Now we are seeing decreases.  Forecasts show population growth rates continually decreasing.]  

Question 2

  1. What resources are important for sustaining life?
  2. How might an increasing population affect the supply of these resources?
  3. How is your answer in (b) related to the concept of scarcity?
  4. How does our government help to save resources?

[Note to teachers: Things like clean air, water, land, etc. are important for life.  Increasing populations will add stress to the fragile environment and will cause more pollution.  We will deplete resources faster.  Tie this to the concept of scarcity, since increased populations will lead to increased scarcity.  Governments sometimes use regulation to save resources.  Get students to think about mandatory recycling programs, laws that reduce pollution and littering laws, etc.]  

Calculating Population Growth Rates

babyPopulation growth rates are simple to calculate.  You need only two numbers in order to determine how fast a population grows.  The first is a country’s Birth Rate.  Birth rate is the number of births per 1,000 people for a given year.  For example, if a country had a birth rate of 20 in 1998, that means there were 20 babies born per 1,000 people.  (Thus, if the country has 100,000 people, it can be estimated that the number of births was 2,000).  The second number needed is the Death Rate.  The death rate tells the number of deaths per 1,000 people for a given year.  If a country had a death rate of 15 in 1998, this means that an estimated 15 people died for each 1,000 citizens in that year. (See an example of birth and death rates for Afghanistan in the Afghanistan Factbook .)

Calculating population growth rates is straight-forward.  You simply plug birth rates and death rates into the following equation:

 % Growth Rate = (BR-DR) / 10.

For example, Brazil had a birth rate of 21 and a death rate of 9 for 1998.  Plugging this into the above equation gives

= (21 – 9) / 10

= 1.1%
which tells us that the population of Brazil grew by 1.1% in 1998.

Question 3

Is there anything related to population that is not captured in the growth rate equation?  Can you think of something that helps determine a country’s population but is not a birth or a death?

[Note to teachers: The growth rate equation tells us nothing about population effects related to immigration.  We are using only “natural growth rates” that do not incorporate immigration data.]

Comparing MDCs and LDCs

There are clear patterns of population associated with More Developed Countries (MDCs) versus Less Developed Countries (LDCs).  MDCs are countries that have relatively high per capita incomes (income per person) and standards of living.  These countries have experienced long-term economic growth and they are technologically advanced.  Some examples of MDCs are the United States, Germany, and England.  LDCs are countries that have not benefited from long-term economic growth.  LDCs have relatively low standards of living and low per capita incomes, and they generally rely on developed countries for technology.  Countries such as Tanzania and Ethiopia are considered LDCs.

Start by completing the following tables.  Use the Bureau of the Census page that details .  You will have to go to the chart with the country names and highlight the specific country for which you would like data.  Then click on “Submit Query.”  You will connect with a data set.  Notice that the first two lines of the data provide the country’s birth rate and death rate for the year for which the most recent data are available (currently, 1998).  You will have to do this for each country on the chart.

Fill in the blank spaces in the table, using the equation for calculating population growth rates and the country-specific data.

Table 1. Population Growth Rates for MDCs                                                                                    


Pop. Growth Rate












United Kingdom


United States



Table 2. Population Growth Rates for LDCs


Pop. Growth Rate













Question 4

  1. Which country has the highest population growth rate?
  2. Which country has the lowest population growth rate?
  3. Does any country have a population growth rate that is less than 0?  If so, what does this mean?
  4. Can you form a general conclusion about how population growth rates differ for MDCs versus LDCs?

[Note to Teachers: Students should see that the MDCs have lower population growth rates than LDCs.  Two interesting countries are Belgium, which has a 0% growth rate currently, and Germany, which has a negative growth rate.]

How is the United States Doing?

Answer the following questions so that you can make a conclusion about population growth in the United States.

Question 5

  1. In respect to population growth, how does the U.S. compare to other MDCs?
  2. How does the U.S. compare to the LDCs?
  3. If you were asked whether or not the United States has a population problem, what would you answer? Why?

[Note to teachers: The U.S. has a higher growth rate than many other MDCs.  This might imply that we should focus on our population growth. But, in comparison to the LDCs, the U.S. population growth rate clearly looks low.  There is not really a correct answer to question (c); this topic is heavily debated.]

How Long Will It Take a Population to Double?

beachThere is a very simple way to estimate how many years it will take for a country’s population to double (this is called the “doubling time”).  Use the following equation to calculate this information.  Simply take the number 70 and divide by the country’s population growth rate:

# of years for the population to double = 70 / (growth rate)
[NOTE: This calculation yields only an estimate. This method of calculating the doubling time assumes that the growth rate will stay constant.  Clearly, population growth rates change over time.]

Question 6

  1. Using the growth rates you calculated in Task 3, calculate the doubling times for the United States, France, Zimbabwe, and Ethiopia.
  2. What conclusions can you make about doubling times in MDCs versus LDCs?

[Note to teachers: U.S.=140 years, France= 233 years, Zimbabwe=64 years, Ethiopia= 29 years. Clearly the doubling times are much lower for LDCs.]

Controlling Population Growth–The Case of China

Americans are free to have as many children as they wish.  In China, the government restricts the number of children each family can have.  Children must be “registered,” and families that exceed the allowable number of children will not be given important resources–for example, education for the extra child.  The goal of the Chinese government is to reduce the rate of population growth in China.  However, there are other social implications of this policy.   Read the article “6.3 Brides for Seven Brothers ” to learn more about the situation in China.


  1. In China, what is happening to the population of boys as compared to the population of girls?
  2. What long-run problems has the one-child policy created?
  3. How do you think Americans would react if the U.S. government imposed this type of regulation?

[Note to teachers: The population of Chinese boys is growing faster than the population of girls.  Boys are “favored” over girls, and this has led to infanticide, especially in the case of baby girls.  Also, there is a concern about dating and marriage in the future when there will not be enough women to match the population of men.  This will lead to marriage outside of race, etc.  Ask your students to discuss how Americans decide how many children to have.] 


Environmentalists and economists have studied trends in population growth. As population grows, resources will be used up faster and faster and more pollution will be created. The rate of population growth is an important variable and for years, population was growing at an increasing rate. Fortunately, population growth rates are now decreasing, which means that population is still growing but at a slower rate than before. While this unit does not address all aspects of the population debate, it does provide an introduction to the topic.