The Basics

Overpopulation of humans is a big problem to the environment and a big threat to biodiversity.  Since the 1800’s, the population has increased because we have developed more food, hygiene, and medicine.  This means humans are able to live longer and have more children which increases the population.  Overpopulation of humans doesn’t mean that the population has to be very large, but that there aren’t enough resources to spread around among the people.  Therefore, humans often destroy the environment to get those resources.  This often causes habitat loss for some animals which is a threat to biodiversity.

The growth of the human race has been rising rapidly since the population explosion in the 1900’s.  A population explosion occurs when the population increases at a very fast rate.  The population explosion happened between 1900 and 1950.  The population went from barely over 1.5 billion to over 2.5 billion in 50 years!  By the time it got to 1999, the population of the world was over 6 billion!  It is predicted to be around 11 billion in 2050.  It is very important to keep track of the population, because we need to be able to calculate how many resources we will require.

A mega-city is a city with a population of over 10 million people.  Most mega-cities are what they are today because people came there for jobs.  When mega-cities form, there is an enormous loss of habitat for native species and a big drop in the area's biodiversity. Here is a list of the top ten mega-cities and their populations that were recorded in 2006:

1. Tokyo with a population of 34,200,000
2. Mexico City with a population of 22,800,000
3. Seoul with a population of 22,300,000
4. New York City with a population of  21,900,000
5. São Paulo with a population of 20,200,000
6. Mumbai with a population of 19,850,000
7. Delhi with a population of 19,700,000
8. Shanghai with a population of 18,150,000
9. Los Angeles with a population of 18,000,000
10. Osaka with a population of 16,800,000

The Causes and Effects

Some causes of human overpopulation are:

• Development of better hygiene
• Development of food production
• Development of better medicine
• People living longer than they used to
• People being healthier and having children

The effects of human overpopulation are:

• Building over farmland for homes
• The resources run out
• Poverty
• Pollution
• Loss of biodiversity

Building over farmland is particularly bad because farms produce lots of food.  By doing that, it means some of the resources run out because we are building over them. 

Poverty is also an effect because there isn’t enough room for everyone to live in a decent home and there aren't enough jobs for everyone. 

Pollution is another big problem. Because there are so many people, we need to have lots of factories producing the goods that people need. Some of these factories produce air pollution and some send waste through pipes and those pipes lead to the water. 

Where is it Found?

Overpopulation is found all over the globe in many big countries.  Here is a list of the top ten most populated countries that were recorded in 2006:

1. China
2. India
3. United States of America
4. Indonesia
5. Brazil
6. Pakistan
7. Bangladesh
8. Russia
9. Nigeria
10. Japan  

What Can You Do?

There are many things to do about overpopulation.  You can donate time or money to help someone in need, conserve energy in your daily life, grow your own food or start a local garden, and help to become active in helping protect human rights.  Another thing you can do is help make a greenbelt.  Greenbelts are large amounts of land surrounding a town or city.  This leaves less room to live, which means that the area wouldn’t be as densely populated.  This decreases the need of resources.  Here are some organizations that can help solve this problem:

• Amnesty International
• World Wildlife Fund
• The United Nations Environment Programme
• Greenpeace
• Oxfam Australia