This document is the note I have taken specifically for the IB Geography course based on the book “Our Changing Planet” by Stephen Codrington. It covers chapter 2. My notes does not include the Cases Studies, but I wrote the page numbers from the textbook that covers all of the Case Studies.
Population Change
- Global population is now about 7.4 billion
- Thomas Malthus said that earth could only support a finite population size
because food supplies are limited. He said that natural increase in the
human population increases in a geometric progression, food production
only increase in an arithmetic progression
- The growth in the world population has been caused by a combination of
death rates being lowered and life expectancies increasing
- Death rate: the proportion of the population that dies in a particular year
- Infant mortality: death rate of young children
- Average life expectancy: the number of years that a child born in a particular
country in a certain year can expect to live
- Just like population growth has been unevenly distributed in the [ast, growth is
likely to be unevenly distributed in the decades ahead.
- The structure of a population refers to the sex and age distirubtion of the
population. This is often shown as a graph with the number of proportions of
each age group shown as horizontal bars from a central vertical column that
represents age groups. These graphs are known as population pyramids, or
age-sex diagrams (See figure 2.5 on page 62)
- Children and adolescents (under 15 years old)
- The working-age population (15-64 years old)
- The elderly population (above 64 years old)
- A population pyramid with a wide base that narrows quickly upwards
represents a population with a high birth rate, a high proportion of
young people and a rapidly growing population.
- A population pyramid with steep vertical sides represents an aging
population with a low birth rate
- Developing countries tend to have a population structure with a wide
base, indicating that a large proportion of the population is below 15
years of age.
- Industrialized countries have population pyramids that have a
narrower base.
- Population pyramids with a narrower base are evidence of an ageing
population and a slower rate of population increase, or even a
declining population size
- Fertility rates: number of births per woman
- Fertility rates are very high in developing regions such as Africa and parts
of the Middle East, but low in most industrialised regions
- The rate of population increase in any area can be calculated by adding the
rate of natural increase and the rate of net migration
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