Overpopulation means that the population of a place is too high. Specifically, there are too many organisms of a certain species in a habitat, so the number of organisms living there is larger than the carrying capacity of the habitat. The habitat cannot support these numbers over time without hurting itself.

The term "overpopulation" is most often used to refer to the number of humans living on Earth.[1]

Human overpopulation

The world's population has greatly increased in the last 50 years. The main reason is the reduction in death rate, especially for infants and children. The result is that many more people survive to the age when reproduction is possible.

  • Reduction of death rate
  1. By reducing the effect of infectious diseases
    1. widespread use of antibiotics against bacterial diseases
    2. increased use of vaccination against some viral diseases
    3. wider provision of clean water (modern sewage systems etc.), which reduces parasitic diseases.
  2. By increasing food production
    1. the world-wide use of DDT, and later anti-pest treatments.
    2. the invention of high-yielding varieties of crops and later, genetically-engineered crops.[2]

Steve Jones, head of the biology department at University College London, has said,

"Humans are 10,000 times more common than we should be, according to the rules of the animal kingdom, and we have agriculture to thank for that. Without farming, the world population would probably have reached half a million by now".[3]

Against this background, the reduction in fertility has had little effect, except perhaps in China.[4] The use of the contraceptive pill has transformed the lives of women in rich countries, but has made little impact in poor ones.

File:Population growth rate world.PNG
Human population growth rate in percent, with the variables of births, deaths, immigration, and emigration 2006
File:World population history.svg
World population 1950–2010

The recent rapid increase in human population over the past two centuries has raised concerns that humans are beginning to overpopulate the Earth. The planet may not be able to sustain larger numbers of people. The population has been growing since the end of the Black Death, around the year 1400.[5] At the beginning of the 19th century, it had reached roughly 1,000,000,000 (one billion). Rapid population growth occurred all over the world, especially after World War II. By 1960, the world population had reached 3 billion, and it doubled to 6 billion over the next four decades. As of 2011, the estimated annual growth rate was 1.10%, down from a peak of 2.2% in 1963, and the world population stood at roughly 6.9 billion. In 2014, it is over seven billion.

Current projections show a steady decline in the population growth rate, with the population expected to reach between 8 and 10.5 billion between the year 2040[6][7] and 2050.[8]

The scientific consensus is that the present population growth and increase in use of resources is a threat to the ecosystem. The InterAcademy Panel Statement on Population Growth called the growth in human numbers "unprecedented", and stated that many environmental problems, such as rising levels of atmospheric carbon dioxide, global warming, and pollution, were made worse by the population expansion.[9] At the time, the world population stood at 5.5 billion, and optimistic scenarios predicted a peak of 7.8 billion by 2050, a number that current estimates show will be reached around 2030.[10][11]

Potential solutions

The solutions usually suggested are better education and widespread free contraception (birth control). Many pregnancies are unplanned (40%) or unwanted.[12]

There are powerful forces working against birth control. Religious and traditional beliefs often favor large families. Few governments have tackled the problem seriously.


  1. "Overpopulation". www.tititudorancea.org.
  2. Global food crisis looms Global food crisis looms as climate change and population growth strip fertile land. Guardian.co.uk. 31 August 2007.
  3. Leading geneticist Steve Jones says human evolution is over, The Times, 7 October 2008.
  4. "World Birth rate – Demographics". Indexmundi.com. Retrieved 17 October 2011.
  5. World population estimates
  6. "World Population Clock — Worldometers". Worldometers.info. Retrieved 2010-08-01.
  7. "International Data Base (IDB) — World Population". Census.gov. 2010-06-28. Retrieved 2010-08-01.
  8. "World Population Prospects:The 2008 Revision" (PDF). Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. June 2009.
  9. "Register (Login)". IAP.
  10. http://esa.un.org/unpp/p2k0data.asp
  11. Netherlands Again Number One Donor to United Nations Population Fund. United Nations Population Fund (UNFPA).
  12. Population growth driving climate change, poverty: experts. Agence France-Presse, 21 September 2009.