1. Populations in transition

In 2011 the human population of Earth reached 7 billion (see link below)


For an estimate of the current population visit census.gov

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World population growth since 1800

Key terms – Births

Crude Birth Rate (CBR) – The number of births, per 1000 people in a population.

Total Fertility Rate (TFR) – The number of children a woman is expected to have during her lifetime, based on current birth rates.

See the CIA World Fact Book for data on total fertility rates.

Key terms – Deaths

Crude Death Rate (CDR) – The number of deaths per  1000 people in a population.

Infant Mortality Rate (IMR) – The number of deaths of children <1 yr old per 1000 people in a population.

Child Mortality Rate (CMR) – The number of deaths of children <5 yrs old per 1000 people in a population.

Other key terms

Natural Increase Rate (NIR) = Crude Birth Rate – Crude Death Rate

Life Expectancy – The number of years that the average person, born in a given place may expect to live. Read this article from the BBC about how life expectancy is changing in some countries

Population momentum –  Population Momentum from Britannica

For population statistics, take a look at: Gapminder.org

This Factors influencing Birth & Death Rates sheet outlines some of the reasons behind changes in birth & death rates.

One of the factors influencing fertility rates in different countries is the infant mortality rate. This link provides more detail.


Hans Rosling talks about Population momentum, a key issue in population growth.

Professor David Suzuki speaks about the dangers of overpopulation:

The importance of birth rate:




BBC News looks at falling infant mortality rates in Africa. There is a good case study of what has been happening in Malawi. Click here for details.
Birth rates have been falling in Ethiopia. See BBC News

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