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

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

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.

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

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

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

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

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.

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)

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