# World Population

## Outline

1. Population in Space and Time.
• Natural Change
• Migration
• Exponential Population Growth
• Population Concentrations
• Ten Largest Countries
2. Population Growth
• Survivorship
• Population Pyramid
• Demographic Transition
3. Checks on Growth
• The Malthusian Theory
• Logistic Population Curve
• Zero Population Growth (ZPG)
• Controlling the World's Population
4. Population Projections
• Formula
• Example
5. References
6. Review Questions

## Population in Space and Time

Population growth results from a greater number of births than deaths. To determine the natural change for a country, one takes the country's birth rate minus the death rate, divided by 10. For instance, if we wanted to know the natural change for Norway, we would take Norway's birth rate (13) minus its death rate (9), divided by 10. Norway's natural change would be 0.4. On the other hand, Pakistan's birth rate is 31, and their death rate is 8.  Therefore, the natural change is 2.3.

Migration also affects population change for a country. Migration simply means, a change in residence that is intended to be permanent. Generally, migration has economic causes and leads to a movement of people from poorer to richer countries.

Population has been growing exponentially since the latter part of the 1700s. The exponential growth rate occurs if a population has a high birth rate through time and is counter-balanced by an equal death rate through famine or disease. With exponential growth the birth rate alone controls how fast (or slow) the population grows

If we look at a population distribution map, we can see that certain areas of the world are more populated than others. East Asia, South Asia, Europe and Eastern North America contain the four major concentrations of population. If we look closer at these four areas of concentrations, we can identify "clusters" of dense population. In East Asia, we notice that the population is denser near the valleys of China's major river systems that are associated with that nation's agricultural regions. In South Asia, there is a large cluster in northern India near the Ganges River. This cluster almost equals the density of East Asia and there are estimates that India's population could exceed East Asia during this next century. The European cluster is associated with manufacturing centers in Western Europe. The North American clusters are greatest in concentrations along the eastern and western coasts, with widely scattered pockets throughout the continent.

The top ten most populated countries are listed on the table below.

 Country Population 2007 Percentage of world population Country Population 2050 Percentage of world population China 1,318 million 19.9% India 1,747 million 26.4% India 1,132 million 17.1% China 1,437 million 21.7% United States 302 million 4.6% United States 420 million 6.3% Indonesia 232 million 3.5% Indonesia 297 million 4.5% Brazil 189 million 2.9% Pakistan 295 million 4.5% Pakistan 169 million 2.6% Nigeria 282 million 4.3% Bangladesh 149 million 2.3% Brazil 260 million 3.9% Nigeria 144 million 2.2% Bangladesh 231 million 3.5% Russia 142 million 2.2% Dern. Rep. of Congo 187 million 2.8% Japan 128 million 1.9% Philippines 150 million 2.3%

The percentage listed after each country represents that country's population as a percentage of the total world's population. In order to determine any country's percentage of the total world's population you take that country's total population and divide it by the total population of the world, which is then multiplied by 100. For example, China's total population is 1.318 million (1.318 divided by 6.625 X 100 = 19.89). We can then say that roughly 20 percent of the world's population lives in China.

## Population Growth

Survivorship, or the length of life, has been increasing due to many factors including better overall health care, improved medical technology and a sustained effort by the United Nations to provide greater awareness in order to improve the quality of pre-natal care around the world. We have also been more successful in finding ways to help feed starving people in times of crisis. However, factors such as politics and warfare have restricted our efforts to help those in need. As a whole, more and more children of the world are living longer today than in the past. There are still areas of the world where the survival rates of the first one to two years of life are significantly lower than in the more developed countries. The infant mortality rate in developed countries is 6 per 1000 live births, while in less-developed countries, it is 57 per 1000. This has a major influence on survival rate. Across the world, adults are generally surviving to live to an older age as well. Modern medicine has also made a significant contribution to people living longer.

A population pyramid can be used to understand reasons for population growth, Such a diagram shows the age-sex structure of a country. This compares the male population to the female population in different age groups. Countries with a slower growth rate will have a "straighter" population pyramid. If the population pyramid has a more "pyramid like" shape, with a broader base and a narrow summit, the population of the country will continue to increase. If you were to compare India's broad-based population pyramid to France's narrow-based population pyramid, you would be able to easily notice the difference.

Geographers also look at demographic transition models. These are multi-stage models based on Western Europe's experience of changes in population growth as countries undergo industrialization. There are four distinct stages to the model. The first stage is called high stationary, and is characterized by both high birth and high death rates. Currently there are no countries in this category. The next stage is known as the early expanding stage, which is characterized, by high birth rates and low death rates. Very poor countries such as Africa and Asia, can be found in this category. The third stage is known as the late expanding stage and is very much like the second stage. It has high birth and death rates, but the birth rates are beginning to decrease. The final stage is called low stationary and includes both low birth and low death rates. Underdeveloped countries are generally found in stages two and three and the more developed nations are in stage four.

To further illustrate these differences lets compare a couple of examples. Kenya's birth rate is now listed at 40 per 1000 people and the death rate is 12 per 1000. Notice the large gap between these two figures. On the other hand, the birth rate per 1000 people in the United States is listed at 14 and the death rate is 8 per 1000. Germany is in an interesting position where the death rate is exceeding the birth rate. (Germany has 8 births per 1000 and 10 deaths per 1000.) There are demographers that see this trend of negative growth as a fifth stage in demographic transition, but most simply view it as a temporary condition associated with the fourth stage.

## Checks on Growth

Thomas Malthus, a theorist and statistician who lived in the 1800's, developed a theory of population growth and the capacity for food production. The Malthusian Theory stated that human population would be controlled by the planet's ability to produce the food to feed it. This was referred to as the "Biotic Potential". During Malthus time, critics of his theory did not believe that the world's population would ever reach that point. However Malthus did initiate a debate that still rages today and the issue of natural and artificial checks on the growth of population is still the subject of a great deal of research and speculation.

The logistic population formula compares the amount of population density and the availability of resources to population growth. Dolpe Quetellent, and Pierre-Francois Verhulst founded this formula near the 1830's. They also speculated an upper limit to population, but predicted a slow-down in population as the upper limit is reached.

The concept of ZPG, or "zero population growth" is often used in relation to population growth. The term was widely used in the 1970's when the United Nations debated over how to control the growth of the world's population. The issue of population growth was also a more prominent concern among the general public. Zero population growth was often cited as an ideal goal for the nations of the world to achieve. Many proponents of ZPG advocated the "two child per couple" concept to discourage the practice of larger families and as a way to shape socially acceptable behavior. However, even with the two-child concept, the population of the world would continue to grow. This is because most of the countries of the world have a large proportion of their population in the younger age group, and duplicating this group at two children per couple would continue to expand population. At this time, the world has a 1.5 or less ZPG replacement production while the United States and the rest of the developed world has a rate of about 2.3 children per family.  This is because the United States and more developed countries have a smaller proportion of their population in the younger age groups.

Developing countries overpopulation affects their resources. The overpopulation has also created a problem for the rest of the world in providing a significant supply of resources to stabilize growth. The issue of population control and planning is also the subject of a raging philosophical debate in some of the more affluent and developed countries of the world, such as the United States. The highly charged emotional debate around the use of abortion and other means of birth control to help control population is a limiting factor in our country's willingness to provide aid. Foreign aid for population control methods and educational efforts often is severely limited and restricted by those who are opposed to abortion and/or birth control under any circumstances. In our country, this issue often puts us at odds with many nations where the issue is not as divisive and politicized.

## Population Projections

Population projections are simply mathematical projections determining the rate of future populations based on current rates of growth. Many equations are used to project future population growth. A basic equation is Nt=P times e raised to the power of (r*t). "Nt" represents the number of people at a future time. "P" is the population at the beginning time. "e" is the base of the natural logarithms (2.71828). "r" is the rate of increase (natural increase divided by 100). "t" represents the time period involved.

One way to understand population projections is by example. In 2000, Mexico had a population of 99.6 million people. We want to predict the future population for the year 2020. We take 2.71828 (e) raised to the power of 0.022 (r), times 20 (t). Therefore, e raised to the power of r time's t is equal to 1.553. Now, the present population (99.6) is multiplied by 1.553, which equals 154.7. Therefore, in 2020, the projected population for the country of Mexico is projected to be 154.7 million people that represents an increase of 55.1 million people in 20 years(See example below).

Nt = (P x E) raised (r * t)

# of people at a future time = (Present Population * base of the natural logarithms) raised (rate of increase * time period)

# of people at a future time = (99.6 x 2.71828) raised (.022 x 20)

# of people at a future time = 154.7 million people

## References:

Marston, Sallie A. World regions in global context: people, places, and environments. Upper Saddle River, New Jersey: Prentice Hall, 2002

Clawson, David. World regional geography: a development approach. Upper Saddle River, New Jersey: Prentice Hall, 2007

Weeks, John. Population. Belmont: Wadsworth Publishing Co, 1992.

H.J. de Blij; Muller, Peter. The world today: concept and region in geography. Dubuque, Iowa: John Wiley & Son, Inc, 2007

World Population Data Sheet. Population Reference Bureau. 2007

## Questions

1. The United States is the world's third largest country but has only what percentage of the world's population? A. 7.9% B. 12.1% C. 4.6% D. 19.2% E. 14.5%

2. Population growth is highest in countries that: A. are industrialized; B. are resource rich; C. are in the early and late expanding stages of the demographic transition; D. are extremely poor with both high birth and death rates; E. none of the above.

3. China has about what percentage of the world's population? A. 20%; B. 38%; C. 14%; D. 27%

4. The total population of an area is the result of the interplay of two sets of forces. These two are migration and: A. emigration; B. immigration; C. natural change; D. Malthusian function.

5. The logistic curve is probably more accurate in describing limits on population growth than: A. the declining curve; B. the geometric curve; C. linear curve; D. inverse curve; E. none of the above.

6. Which state in the demographic transition is characterized by high, unchanging birth rates combined with decreasing death rates: A. high stationary; B. low stationary; C. early expanding; D. late expanding; E. Malthusian Theory.

7. The population age-sex structure of an area can be represented with: A. the ZPG; B. a population pyramid; C. the population potential; D. the population dynamic; E. none of the above.

8. Which one of the following is not one of the world's four largest population concentrations: A. South Asia; B. Europe; C. Eastern Africa; D. Eastern North America; E. East Asia.

9. Given a population of 6.067 billion and a growth rate of 1.7 percent, which of the following formulas would give the population of the Earth in the 15 years? A. 6.067 X e (raised to the power of 0.13); B. 6.067 X e (raised to the power of 0.23); C. 6.067 X e (raised to the power 0.33); D. 6.067 X e (raised to the power of 0.033); E. 6.067 X e (raised to the power of 0.255).

10. The Malthusian Theory, attributed to Thomas Malthus, states that: A. population will continue to grow unchecked; B. population grows in a linear fashion and would exceed food production; C. food supply would keep pace with population growth; D. population increases in a exponential manner while food supply can only increase in a linear, or straight line fashion; E. all of the above.

11. The theory of logistic population growth states that: A. population growth is exponential; B. the absolute amount of food production for the earth varies with the size of the population; C. food supply increases arithmetically; D. there are analogies between human and animal populations; E. there is an absolute limit to food production on Earth and human population growth will decrease as the total population approaches this point.

12. Survivorship is defined as: A. when one spouse outlives the other; B. the amount of a county's population remaining after a great war; C. the length of life; D. when children live longer than two years of age; E. all of the above.

Original update submitted by Bradley Bramer on April 9, 2001. Current update submitted by Mario Morgan, Judd Schroeder, Kirk Mohr on April 10, 2008