Topic 3.1

Population Dynamics

http://edroness.blogspot.mx/2014/03/population-dynamics.html

Human Population Growth

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?

Total Female Fertility Rate (TFR)

Children/lifetime, according to CIA World Factbook 2013 database

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

World Population Distribution

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

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

CalculationsCrude 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

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

CalculationsASBR 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 rateTFR = Total fertility rate

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

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

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)

The Demographic Transition Model

http://edroness.blogspot.mx/2014/03/the-demographic-transition-model.html

The Demographic Transition ModelStage 1/2Expanding

Stage 3Expanding

Stage 4Stationary

Stage 5Declining

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 trickyBirth rate is affected

by:o Existing age structureo Status of women in societyo Level of educationo Availability of family planningo Provision of child benefit

Death rate is affected by:o Existing age structureo Availability of food and clean watero Diseaseo War and conflicto Provision of healthcare

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

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?

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