IB Environmental Systems and Societies

1. Topic 3.1
Population Dynamics
http://edroness.blogspot.mx/2014/0
3/population-dynamics.html

2. Human Population Growth

3. Human Population Growth
• The world’s human population is now thought
to be greater than 7 billion
• Although population is still increasing, the rate
of increase is currently decreasing
• Female fertility rate is decreasing
– 1990 global average = 3.3 children/lifetime
– 2002 global average = 2.6 children/lifetime *
• In developing countries, AIDS related diseases
are having a big impact on population
* Note that this is still above the replacement level. If current trends continue, it may fall
below 2.0 children/lifetime before 2050. Does this mean population will decrease?

4. Total Female Fertility Rate (TFR)
Children/lifetime, according to CIA World Factbook 2013 database

5. The Impact of Increasing Population
• More resources are needed to feed, clothe,
care for, transport, entertain etc.
• However, the resources used by the fastest
growing sections of society (LEDCs) are much
less than MEDCs
• Fertility rate is decreasing and life expectancy
is increasing
• Social security (necessary to care for an aging
population) is not necessarily increasing

6. World Population Distribution

7. Population Changes
• Areas where population is likely to continue increasing:
– North America
– Latin America
• Areas where population is likely to fall:
– China
– Western part of Former Soviet Union
• Areas where population is likely to increase, but at a much
lower rate:
– Sub-Saharan Africa
– India and Pakistan

8. Calculations
Crude Birth Rate (CBR) (births/1000 people)
= total number of births x 1000
total population
Age-specific Birth Rate (ASBR) (births/1000 women)
= total number of births
1000 women of a specified age group
This does not consider the age or sex structure of a society
The highest birth rates are in LEDCs. In MEDCs birth rates (and fertility rates have fallen

9. Calculations
Crude Death Rate (CDR) (deaths/1000 people)
= total number of deaths x 1000
total population
Total Fertility Rate (TFR)
= average number of births per woman per lifetime
General Fertiity Rate (GFR)
= average number of births per 1000 women aged 15 – 49

10. Calculations
Natural Increase Rate (NIR) = CBR - CDR
Doubling time (years)
= 70
percentage growth rate
Doubling time is the time it takes for a population to double in size, assuming growth
rate remains constant and an average life expectancy of 70 years

11. Calculations
ASBR TFR
Age
Group
15-19 20-24 25-29 30-34 35-39 40-44 45-49
France 9.3 71.0 137.0 91.0 36.6 7.3 0.5 1.76
Germany 12.4 57.3 108.8 81.1 28.2 5.1 0.3 1.47
Belarus 45.2 168.0 88.1 39.5 14.4 3.2 0.2 1.79
Russia 55.6 156.8 93.2 48.2 19.4 4.2 0.2 1.89
ASBR = Age-specific birth rate
TFR = Total fertility rate

12. Factors Affecting Fertility Rates
• In general, the higher the level of education, the lower the
number of children per family
• LEDCs generally have introduced programmes to reduce
birth rates (e.g. family planning clinics, sex education)
• Government imposed controls on birth rate have generally
been unsuccessful (except perhaps in the case of China)
• Some MEDCs have introduced programmes to increase
birth rate (e.g. Singapore, France)
• In general, as economic prosperity increases, birth rate
decreases
• Recession and unemployment is linked to reduced birth
rate (due to parental perception that they cannot afford to
bring up children)
• The higher the child mortality rate, the greater the
perceived need to have more children

13. Factors Affecting Death Rates
• Improved health care leads to an aging population, but
is not necessarily reflected by a reduced CDR. Longer
life expectancy leads to a larger number of deaths at
the same time
– CDR in Denmark = 11 deaths/ 1000 people
– CDR in Mexico = 5 deaths/ 1000 people
• LEDCs generally have low life expectancies and high
death rates (although the trend is for improvements in
both)
• The CDR in LEDCs has however been increased due to
the impact of AIDS
http://edroness.blogspot.mx/2014/03/the-impact-of-aids-on-death-rate-in.html

14. Population Pyramids
http://edroness.blogspot.mx/2014/03
/blog-post_30.html
• Wide base indicates high birth
rate
• Narrow base indicates low birth
rate
• Vertical sides indicate low death
• Inward curving sides indicate high
death rate
• Lack of symmetry shows
differences in birth and death rate
between the sexes
• Bulges or constrictions suggest
high rates of migration or
immigration, specific to age
groups (or war)

15. The Demographic Transition Model
http://edroness.blogspot.mx/2014/03/the-demographic-transition-model.html

16. The Demographic Transition Model
Stage 1/2
Expanding
Stage 3
Expanding
Stage 4
Stationary
Stage 5
Declining

17. Using Population Models
• You can use models over a range of scales and
the factors are different at different scales
– On the national scale, immigration and emigration
are factors, whereas on the global scale they are
not
• There are so many variables to take into account
that making accurate predictions is very tricky
Birth rate is affected by:
o Existing age structure
o Status of women in society
o Level of education
o Availability of family planning
o Provision of child benefit
Death rate is affected by:
o Existing age structure
o Availability of food and clean water
o Disease
o War and conflict
o Provision of healthcare

18. Using Population Models
• UN Estimates of world
population by 2100 vary
widely depending on the
assumed variables
• The further we project
into the future, the
greater the disparity
between the estimates
• The widely quoted figure
is 9 billion by 2050
14 billion
9 billion
5.5 billion

19. Using Population Models
• The biggest challenge may not be dealing with
global population growth, but with global
population ‘greying’ in MEDCs and LEDCs
• Currently MEDCs have around 4 workers per
retiree, but by 2050 it is expected to be around 2
• The solution may lie in:
– Expanding the population of workers (increasing
retirement age and getting more women into the
workplace)
– Increasing productivity
– Persuading people to save more for their retirement
Do you think governments in MEDCs may be unwilling to implement such policies?

20. Questions
1. Describe the nature and implications of
human population growth
2. Outline the factors that affect birth rates and
death rates
3. Discuss the effectiveness of population
models