1. Changing populations
How has the world’s population changes and how can we represent that?
Understand the Demographic Transition Model and how to interpret and population pyramid

2. Changing populations
The World’s population is predicted to be 9 billion in 2050
Every year, the population increases by 78 million
The rate of increase varies from country to country but it is far higher in LEDCs than MEDCs
For example, it is predicted that it will take Africa 26 years for its population to double, while it will take North America 117

3. The changes in population are often called natural increase
Changing populations
The changes in population are often called natural increase
Natural increase can be calculate from subtracting the number of people dying in one country (the death rate) from the number of people that are born (the birth rate). The larger the natural increase the faster the population will grow.

4. Changing populations
Population change takes place over four stages an are illustrated in the Demographic Transition Model

5. Changing populations LEDC MEDC
High
Birth rate and death
rate per 1000
Low natural increase, population may decline as birth rate falls below death rate
Low
Natural increase rises, population grows as death rate falls and birth rates remain high
Natural increase is low
Natural increases falls as both birth and death rates fall
LEDC
MEDC

6. Changing populations Changes from Stages one to four are derived from:
improved medical provision; improved living conditions; better educational provision and access especially for women and state sponsored family planning and general quality of life improvements

7. MEDCs con be found in stage four
Changing populations
MEDCs con be found in stage four
LEDCS mainly in stages one and two as the lack of economic development restricts education land social improvements
For example, compare fertility rates of 1.6 in the average MEDC country to over 7 in LEDCs such as Uganda

8. Changing populations
Dependent
population
Working
population
Dependent
population
This is a population pyramid. It is the best way to represent the overall structure of a population. One can read an awful lot of information from this graph.

9. Changing populations
Population pyramids can used to calculate the Dependency Ratio (the number of people that are largely unable to work)
MEDC = DR of
50 – 70
LEDC = DR of
over 100
The Dependency ratio =
(No. of children below 15 + no. of people over 65) X 100
Number of those of working age (16 -64)

10. Changing populations
How can we compare and contrast the two population pyramids?