4. Population growth

4.1 Earth's population

The population of planet Earth is currently approximately 7,8 billion or 7 800 000 000.

The countries with the highest populations are located in Asia. Both India and China have over a billion inhabitants. The population of India has been estimated to grow even more during the next decade. All other nations are behind these two Asian countries when it comes to population. The United States of America has the third-largest population in the world at 320 million inhabitants.

Earth's population has grown at a significantly accelerated rate during the last few centuries and decades, when compared to other times in human history. During the 2020s, the planet's population will rise above 8 billion. The planet's total population has been estimated to reach 9 billion by the year 2050. Overall, Earth's population has been estimated to eventually reach 10 billion before it will begin to decline. However, as these figures are only estimates, it is difficult to tell exactly when and how this will take place. 

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In industrialized countries, the birth rate has steadily declined over the course of the last 50 years. The birth rate has also begun to decline in some developing countries. However, the effects of this decline are often visible only after several years. The European population is thought to continue its decline over the next couple of decades. 

In China, the birth rate has declined at an alarming rate. This is thought to pose problems for Chinese society over the next few decades. In addition, China's birth rate is characterized by the fact that approximately 20 % more boys than girls are born every year. This causes problems between the sexes. In contrast, the African population has been estimated to even quadruple during the next century. This is likely to cause an increase in migration if living conditions in Africa cannot be sufficiently improved.

Population growth now



Population growth by continent.​

4.2 Birth and mortality rates

Population growth is a term that describes the rate and amount by which the number of people on planet Earth grows. The population growth of a region is affected by its birth rate, death rate, as well as the amount of migration to and from it. 

The birth rate describes the number of children born per thousand inhabitants each year.

Likewise, the death rate describes the number of deaths per thousand inhabitants each year.

Migration describes the way in which people move between different regions. The effects of migration are only visible in these regions, but are not reflected in the total population of the planet. There are two types of migration: migration that is directed in a certain region (immigration) and migration that is directed away from a certain region (emigration).

Let's study the population growth of an area by using an example. If 100 000 children are born in a certain area during a year, 85 000 people die during the same year, 5 000 people move to the region and 3 000 people move away from the region, what happens to the population? The answer is found by completing a simple equation: 100 000 - 85 000 + 5 000 - 3 000. The result is that the area's population grows by 17 000 inhabitants.

4.3 Earth's population is steadily growing

As discussed above, the planet's population has grown rapidly during the last couple of decades – and even though population growth has been slowed down in certain areas by the decrease in the birth rate, the planet's population still continues to grow. This is due to the fact that even more young adults are able to form families and produce children. This development will slow down only during the course of the next couple of decades. This phenomenon can be studied using the concept of the fertility rate.

The fertility rate describes the number of children that a woman between the ages of 15 and 49 will give birth to on average. The total fertility rate of our planet has steadily declined from 3,4 to 2,5. This means that women on Earth give birth to approximately 2,5 children on average. In some developing countries, the fertility rate has decreased from 6 to 3, but continues to be extremely high in some areas. In Europe, the fertility rate is just under 2, whereas in Africa it is around 5. Some of the highest fertility rates in the world are in African countries: for example, the fertility rate of Niger is 7,6.


Africa is the continent with the highest fertility rate in the world. 



Fertility rate by country. Almost all European countries have a fertility rate below two. This means that, on average, European women give birth to under two children during their lifespan.

Population growth is also increased by the decrease in the global mortality rate. Access to basic health care and hygiene, as well as to advances in medicine, have all helped to decrease the mortality rate of the planet. These advancements have made it possible to protect people from diseases and treat people back to health when illness strikes. Infant mortality has also decreased as vaccines have become more effective. This also results in a lower birth rate, as people do not have to produce as many children to guarantee their own survival.

HIV was previously thought to have a drastic effect on population growth, but its influence has been lower than expected. This is despite the fact that even 25 % of the populations of some African countries are affected by the virus. The effect of wars on population growth has likewise been relatively small.

4.4 The effects of population growth

During the next couple of decades, controlling population growth will become increasingly important in terms of the planet and its inhabitants. Although the rapid population growth of the planet is widely regarded as a global problem with wide-ranging consequences, it is difficult to come up with reasonable methods of controlling it. For example, different restrictions on giving birth to children are quite problematic, potentially violating human rights.

It was previously thought that population growth would be limited by the amount of food and energy production available on the planet. However, advancements in both food production and energy production have proven this hypothesis to be false. However, one significant problem is that the total amount of food and energy on planet Earth are distributed unevenly. In some areas, more food is produced than is necessary, while other areas suffer from yearly famines.


Water shortages are a common problem in many regions. Pakistan.

Population growth has led to water shortages in many areas. Shortages of water and other natural resources is thought to cause disagreements and even wars between neighbouring nations in the future. After this occurs, large numbers of refugees are likely to move to neighbouring countries or even further in the world.

The amount of pollution and waste is also estimated to increase drastically if the planet's population continues to grow at the current rate. As jobs and livelihoods continue to be concentrated in large cities, the risk of urban decay can also become a significant problem. This is already a problem in some developing countries.


The rapid movement of people from rural areas to large cities has resulted in slums in some cities of developing countries.​

4.5 Limiting population growth

When we undertand the causes and effects of population growth, the next problem becomes how to limit and control it.

One of the most effective means of limiting population growth is providing schooling for girls. When children have access to education, they also gain opportunities for new kinds of careers, and have a chance of making decisions about their own life. Providing girls and young women with a better access to education is an important step in decreasing high birth rates in developing countries, as it makes women less dependent on men for gaining their livelihood. When being a mother of a family is no more the only option for young women, the birth rate can be slowed down.

Other means of decreasing high birth rates is providing people of developing countries better access to birth control and family planning. In some developing countries, contraception, sexual health and family planning are not taught in schools. As a result, some developing countries have started to experiment with compulsory lectures on these subjects for young couples that are getting married.

Another significant factor is providing good health care for children and expecting mothers in developing countries. This would have beneficial long-term effects. 

The costs of these methods could be only a fraction of the costs currently produced by unlimited population growth in developing countries. As over 90 % of the planet's total population growth takes place in developing countries, efforts to help contain population growth should be concentrated to these countries.


Health care and education are important means of limiting uncontrolled population growth in developing countries. 

4.6 Population pyramid

A population pyramid, also known as an age pyramid, is a diagram that displays the age and sex distribution of a population. It often resembles a pyramid, but can take a variety of shapes depending on the kind of population it depicts.

The population pyramid consists of horizontal bars that expand in both directions. The bars on the left side of the diagram show the male population, whereas the bars on the right display the female population. The size of the population is displayed horizontally (along the x axis), whereas its age groups are displayed vertically (along the y axis). The sex distribution can be displayed either in numbers or in percentages. Population pyramids help us to understand the age distributions of different populations by presenting their data in an easily understandable form.

Population pyramids can be divided into three distinct types depending on their shape: growing populations (common to undeveloped countries), balanced populations (developing countries) or shrinking populations (industrialized countries).

When studying population pyramids, you will probably notice that the amount of elderly women is often higher than that of elderly men. Although slightly more boys are born than girls in many societies, their mortality rate is also higher. This results in a higher life expectancy for women. When studying national population pyramids, the effects of famines, epidemics and recessions are easily distinguishable. These periods are often visible as a slight size decrease in one age group. Large age groups, such as people born during the post-World War II "baby boom", are also visible in population pyramids.

US Census Bureau 

Summary

  • Population is a term that describes the amount of people inhabiting a certain area.

  • The total population of planet Earth is approximately 7,8 billion people.

  • Earth's total population is steadily increasing, because the planet's birth rate is higher than its mortality rate.

  • The planet's population began to grow as food production, health care, hygiene, and medicine became more effective.

  • The rate of population growth is fast in Africa and Asia.
  • In Europe, the population growth rate is fairly slow.

  • A population pyramid is a diagram that displays the sex and age distribution of a population.