The impact of population increase


Birth rate, death rate and population increase

The population growth rate

The demographic Transmission model

Life expectancy and survival rates

Population pyramids

Impacts of rising human population 

Importance  of species diversity

Simpson’ index of diversity 

Food Security



Birth rate, death rate and population increase


Human populations grow and shrink due the balance between births and deaths. The number of births per 1000 people is called the birth rate, and the number of deaths per 1000 people is the death rate.



The Population Growth Rate


Population growth rate = birth rate death rate

It’s really not a complicated equation, you must admit. Say the birth rate of Switzerland was 23/1000 and the death rate 28/1000. The population growth rate works out as -5/1000 (23/1000 – 28/1000). As a percentage, this is -0.5% growth. This means that there is a net decrease of 5 people per thousand.



The Demographic Transition Model


This is a model used to classify different populations depending on their birth rate, death rate, overall population size, and the factors behind these numbers. There are 5 different stages:


Stage 1

  • Birth rate is high due to lack of contraception and low education.
  • Death rate is also high due to poor sanitation, high infant mortality and starvation.
  • Therefore, overall population size remains low.


Stage 2

  • In stage 2, the causes of high death rate ameliorate, but not those behind high birth rate, therefore:
    • Birth rate is high for all the reasons in stage 1.
    • Death rate decreases as more food becomes available and healthcare improves.
    • Overall population size increases steeply.


Stage 3

  • Birth rate decreases steeply due to contraception availability and family planning.
  • Death rate decreases more slowly.
  • Overall population size…..

Test Call to Action!