Summary of topic 3.1


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IB Environmental Systems and Societies

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Summary of topic 3.1

  1. 1. Topic 3.1 Population Dynamics 3/population-dynamics.html
  2. 2. Human Population Growth
  3. 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. 4. Total Female Fertility Rate (TFR) Children/lifetime, according to CIA World Factbook 2013 database
  5. 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. 6. World Population Distribution
  7. 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. 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. 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. 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. 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. 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. 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
  14. 14. Population Pyramids /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. 15. The Demographic Transition Model
  16. 16. The Demographic Transition Model Stage 1/2 Expanding Stage 3 Expanding Stage 4 Stationary Stage 5 Declining
  17. 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. 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. 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. 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