Population Growth

The population of the world is increasing at an expotential rate - it's growing faster and faster. 

There are two things that affect population size of the world:

Birth Rate - the number of babies born per thousand of the population per year.

Death Rate - the number of deaths per thousand of the population per year. 

When birth rate is higher than the death rate, more people are being born then dying, so the population grows - this is called natural increase. 

Its called natural decrease when the death rate's higher than the birth rate. 

The population size of a country is also affected by migration - the movement of people from one area to another area. 

These are shown by the demographic transition model (DTM)

STAGE 1

Birth rate: High and fluctuating 

Death rate: High and fluctuating 

Population growth rate: zero 

Population size: low and steady

STAGE 2

Birth rate: High and steady

Death rate: Rapidly falling 

Population growth rate: Very high 

Population size: Rapidly increasing 

STAGE 3

Birth rate: Rapidly falling 

Death rate: Slowly falling

Population growth rate: High

Population size: lncreasing 

STAGE 4

Birth rate: Low and fluctuating 

Death rate: Low and fluctuating 

Population growth rate: zero 

Population size: High and steady

STAGE 5

Birth rate: Slowly falling

Death rate: Low and fluctuating 

Population growth rate: Negative

Population size: Slowly falling

Poorer, less developed countries are in the earlier stages of the DTM, whilst richer, more developed countries are in the later stages. 

The population structure of a country is how many people there are in each age group in the population, and how many there are of each sex.

It's shown using population pyramids. 

The changes that happen between each stage of the DTM give countries different population structures. 

Birth rate is high because there's no use of contraception, and people have lots of children because many infants die. 

Death rate is high due to poor healthcare. 

Population growth rate is zero. 

Population structure - life expectancy is low (few people reach old age), so the population is made up of mostly young people. 

Birth rate is high because there's no use of contraception. Also, the economy is based on agriculture so people have lots of children to work on farms. 

Death rate falls due to improved healthcare. 

Population growth rate is very high. 

Population structure - life expectancy has increased, but there are still more young people than older people. 

Birth rate is rapidly falling due to emancipation of women (where they have a more equal place in society) and better education. 

The use of contraception increases and more women work instead of having children.

The economy also changes to manufacturing, so fewer children are needed to work on the farms. 

Death rate falls due to more medical advances. 

Population growth rate is high. 

Population structure - more people are living to be older. 

Birth rate is low - people move to urban areas (urbanisation), their wealth improves and they want more possessions. This means there's less money avaliable for having children. 

Death rate is low and fluctuating. 

Population growth rate is zero. 

Population structure - life expectancy is high, so even more people are living to be older. 

Birth rate is slowly falling - there's less money avaliable to raise children because people have dependent elderly relatives. 

Death rate is low and fluctuating. 

Population growth rate is negative. 

Population Structure - more older people than young people.