Population: Concentration, Density & Growth

1. Population: Concentration, Density & Growth

2. What to write: Write blue words Answer (don’t copy) red questions

3. Purpose/Focus • Describe regions where population is clustered and where it is sparse. • Define three types of density used in population geography. • Understand how to measure population growth through the nature increase rate. • Understand how to measure births and deaths through CBR and CDR.

4. Where do geographers find our information? • Census data (www.census.gov) • Every 10 years • Some aren’t counted. • Take a guess: Who isn’t counted? • What issues might occur when we don’t have 100% participation in the US census? Discuss at table • Redistricting congressional districts happens every 10 years • Sampling: what is it? • Ruled unconstitutional in the US – why might sampling be a good or bad thing in the US?

6. Population Concentrations Clusters – there are four major population clusters in the world. Where are they?

7. Population Concentrations Sparse regions – Dry/Wet/Cold/High • Why don’t people live there? Ecumene: the portion of Earth’s surface with permanent human settlement. • ¾ of population lives on 5% of Earth Image: Canada’s Population Ecumene, 2011

8. Global Ecumene 5000 BC-AD 1900 • What major patterns do you notice on these maps? • Where on Earth have people avoided living? Why? • Why have previously uninhabited regions on Earth become more populated?

10. Population Density • 3 ways to measure density: • Arithmetic • Total number of objects (people) in an area • (total population ÷ by land)

11. Arithmetic Density

12. Population Density • 3 ways to measure density • Physiological • Number of people supported by a unit area of arable land • What is “arable?” • Relationship between the size of a population and the availability of resources in a region

13. Physiological Density

14. Population Density • 3 ways to measure density • Agricultural • Ratio of the number of farmers to the amount of arable land • Lower agricultural densities typically happen in developed countries because of technology and more money

15. Agricultural Density

16. Population • More births than deaths - increase • More deaths than births - decrease

17. Crude Birth Rate (CBR) • Live Births per year per 1,000 people • CBR of 40 means… what?

18. Crude Birth Rate

19. Crude Birth Rate

20. Crude Death Rate (CDR) • Deaths per year per 1,000 people • CBR of 50 means… what?

21. Crude Death Rate

22. Crude Death Rate

23. Natural Increase Rate (NIR) Using what you already know about CBR & CDR, how do you figure out the NIR?

24. Natural Increase Graph: World Population through History • What caused the world population to remain relatively constant for so long? • Why does the world population increase so much in the 1800s? • What might cause the world’s natural increase rate to be negative?

25. World Population Growth 1950-2011

26. Natural Increase Natural increase varies by individual country • What areas of the world would you expect to have above average NIRs? • What areas of the world would you expect to have negative NIRs? • How does migration impact the data for countries?

27. Natural Increase Rate

28. Fertility Total Fertility Rate - average # of kids a woman has

29. Total Fertility Rate

30. Population Pyramids • Shows the percentage (or number) of the total population in five-year age groups • The shape of the pyramid indicates something unique about each population

31. Population Pyramids: What are they telling you?

32. Dependency Ratio • The larger the dependency ratio the greater the financial burden on those who are working to support the dependents. • Europe’s dependency ratio = 47% (equal #s of young & elderly) • Sub-Saharan Africa = 85% (young outnumber elderly 14:1) What kinds of social issues might arise from a large number of young dependents in a region? What issues might result from a large number of elderly dependents?

34. Sex Ratio • Developed countries have more females than males because women live an average of 7 years longer than men. • Male babies outnumber female babies in Asian countries Why might Asian countries have a higher number of male babies?

36. Natural Increase • World population has been growing each year of the twentieth century by 1.2% • All-time peak in NIR occurred in 1963 • Swings in population growth can be impacted by only one-tenth of one percent in the NIR • NIR impacts doubling time • 1.2% NIR = doubling time of 54 years • US NIR = .6 Is the doubling time in the US higher or lower than 54 years?

37. Fertility and Mortality • CDR does not follow similar patterns to that of NIR, CBR, and TFR • Combined CDR for developing countries is lower than that in developed countries • Worldwide difference between high and low CDRs is much less than CBRs • CDRs relate to the level of a country’s development

38. Population Structure • Each country’s population varies over time. • The pattern of a country’s population by age group is known as its population structure. Key Terms: • Population Pyramid: a bar graph displaying a country’s distinctive population structure • Dependency Ratio: number of people who are too young or too old to work, compared to the number of people in their productive years • Sex Ratio: number of males per 100 females in the population

39. Components of Population Growth Key terms: • Crude birth rate (CBR): # of live births in a year per 1,000 people • Crude death rate (CDR): # of deaths in a year per 1,000 people • Natural increase rate (NIR): percentage by which a population grows; CBR & CDR converted to percentages (numbers per 100): CBR% - CDR% = NIR [note: NIR does not take into account migration rates] • Doubling time: number of years needed to double a population, assuming a constant rate of natural increase • Total Fertility Rate (TFR): average number of children a woman will have throughout her childbearing years (15-49) • Infant Mortality Rate (IMR): annual number of deaths of infants under one year of age, compared with total live births