Chapter 6 The Human Population and Its Impact

1. Chapter 6 The Human Population and Its Impact

2. 6-1 How Many People Can the Earth Support? • Concept 6-1 We do not know how long we can continue increasing the earth’s carrying capacity for humans without seriously degrading the life-support system that keeps us and many other species alive.

3. National Geographic 7 Billion and World Population simulator https://www.youtube.com/watch?v=PJ_KQBFN6yI https://www.youtube.com/watch?v=YgI1qshcg7k

4. Crowded Street in China Fig. 6-1, p. 125

5. Human Population Growth Continues but It Is Unevenly Distributed (1) • Reasons for human population increase • Movement into new habitats and climate zones • Early and modern agriculture methods • Control of infectious diseases through • Sanitation systems • Antibiotics • Vaccines • Health care • Most population growth over last 100 years due to drop in death rates

6. Human Population Growth Continues but It Is Unevenly Distributed (2) • Population growth in developing countries is increasing 9 times faster than developed countries • 2050 • 95% of growth in developing countries • 7.8-10.8 billion people • Should the optimum sustainable population be based on cultural carrying capacity?

7. Human Population Growth Fig. 1-18, p. 21

8. 2.5 2.0 1.5 Average annual global growth rate (percent) 1.0 0.5 0.0 1950 1970 1990 2010 2030 2050 Year Fig. 6-2, p. 127

9. Population Time Line: 10,000 BC - 2042 Figure 3, Supplement 9

10. Annual Growth Rate of World Population, 1950-2010 Fig. 6-2, p. 127

11. Where Population Growth Occurred, 1950-2010 Fig. 6-3, p. 127

12. 10 9 8 7 World population (in billions) 6 5 4 Population in less-developed countries 3 2 1 Population in more-developed countries 0 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year Fig. 6-3, p. 127

13. Five Most Populous Countries, 2010 and 2050 Fig. 6-4, p. 127

14. 2010 China 1.3 billion India 1.2 billion United States 310 million Indonesia 235 million Brazil 193 million 2050 India 1.7 billion China 1.4 billion United States 439 million Pakistan 335 million Indonesia 309 million Fig. 6-4, p. 127

15. 11 UN high-fertility variant (2008 revision) U.S. Census Bureau (2008 update) UN medium-fertility variant (2008 revision) 10 IIASA (2007 update) UN low-fertility variant (2008 revision) 9 World population (in billions) 8 7 6 2010 2020 2030 2040 2050 Year Fig. 6-A, p. 128

16. Science Focus: Projecting Population Change • Why range of 7.8-10.8 billion for 2050? • Demographers must: • Determine reliability of current estimates • Make assumptions about fertility trends • Deal with different databases and sets of assumptions

17. World Population Projections to 2050 Fig. 6-A, p. 128

18. Science Focus: How Long Can The Human Population Keep Growing? • Thomas Malthus and population growth: 1798 • Overpopulation and overconsumption • Will technology increase human carrying capacity? • Can the human population grow indefinitely?

19. Natural Capital Degradation: Altering Nature to Meet Our Needs Fig. 6-B, p. 129

20. Natural Capital Degradation Altering Nature to Meet Our Needs Reducing biodiversity Increasing use of net primary productivity Increasing genetic resistance in pest species and disease-causing bacteria Eliminating many natural predators Introducing harmful species into natural communities Using some renewable resources faster than they can be replenished Disrupting natural chemical cycling and energy flow Relying mostly on polluting and climate-changing fossil fuels Fig. 6-B, p. 129

21. 6-2 What Factors Influence the Size of the Human Population? • Concept 6-2A Population size increases because of births and immigration, and decreases through deaths and emigration. • Concept 6-2B The average number of children born to women in a population (total fertility rate) is the key factor that determines population size.

22. The Human Population Can Grow, Decline, or Remain Fairly Stable • Population change • Births: fertility • Deaths: mortality • Migration • Population change = (births + immigration) – (deaths + emigration) • Crude birth rate: # live births/1000/year • Crude death rate: # deaths/1000/year

23. Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population • Fertility rate • number of children born to a woman during her lifetime • Replacement-level fertility rate • Average number of children a couple must have to replace themselves • 2.1 in developed countries • Up to 2.5 in developing countries • Total fertility rate (TFR) • Average number of children born to women in a population

24. Total fertility rate, 1955-2010 Fig. 6-5, p. 130

25. 8 7 Less-developed countries 6 World 5 Total fertility rate (children per woman) 4 More-developed countries 3 2 1 1955 1970 1990 2010 2030 2050 Year Fig. 6-5, p. 130

26. 2010 Rate of Population Increase Figure 11, Supplement 8

27. Total Fertility Rate Figure 12, Supplement 8

28. Case Study: The U.S. Population Is Growing Rapidly • Population still growing and not leveling off • 76 million in 1900 • 310 million in 2010 • Drop in TFR in U.S. • Rate of population growth has slowed • Changes in lifestyle in the U.S. during the 20th century

29. U.S. TFRs and birth rates 1917-2010 Fig. 6-6, p. 131

30. 4.0 3.5 3.0 Births per woman 2.5 2.1 2.0 1.5 Baby boom (1946–64) Replacement level 1.0 0.5 0 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year 32 30 28 26 24 22 20 18 16 14 0 Births per thousand population End of World War II Demographic Depression transition Baby boom Echo baby boom Baby bust 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Fig. 6-6, p. 131

31. 20th Century Lifestyle Changes in the U.S. Fig. 6-7, p. 132

32. 47 years Life expectancy 77 years Married women working outside the home 8% 81% High school graduates 15% 83% Homes with flush toilets 10% 98% Homes with electricity 2% 99% People living in suburbs 10% 52% 1900 Hourly manufacturing job wage 2000 $3 $15 Homicides per 100,000 people 1.2 5.8 Fig. 6-7, p. 132

33. 47 years Life expectancy 77 years Married women working outside the home 8% 81% 15% High school graduates 83% 10% Homes with flush toilets 98% Homes with electricity 2% 99% 10% Living in suburbs 52% 1900 Hourly manufacturing job wage (adjusted for inflation) $3 2000 $15 1.2 Homicides per 100,000 people 5.8 Stepped Art Fig. 6-7, p. 132

34. Several Factors Affect Birth Rates and Fertility Rates (1) • Children as part of the labor force • Cost of raising and educating children • Availability of private and public pension • Urbanization • Educational and employment opportunities for women

35. Several Factors Affect Birth Rates and Fertility Rates (2) • Average age of a woman at birth of first child • Availability of legal abortions • Availability of reliable birth control methods • Religious beliefs, traditions, and cultural norms

36. Girl Carrying Well Water in India Fig. 6-8, p. 132

37. Child Laborers in India Fig. 6-9, p. 133

38. Several Factors Affect Death Rates (1) • Life expectancy • Infant mortality rate • Number of live births that die in first year • Why are people living longer? • Increased food supply and distribution • Better nutrition • Medical advances • Improved sanitation

39. Several Factors Affect Death Rates (2) • U.S. is 54th in world for infant mortality rate • U.S. infant mortality rate high due to • Inadequate health care for poor women during pregnancy and their infants • Drug addiction among pregnant women • High birth rate among teenagers

40. Infant Mortality Rates, 1950-2010 Fig. 6-10, p. 134

41. 200 150 Less-developed countries 100 Infant mortality rate (deaths per 1,000 live births) World 50 More-developed countries 0 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year Fig. 6-10, p. 134

42. Infant Mortality Rates in 2010 Figure 13, Supplement 8

43. Migration Affects an Area’s Population Size • Economic improvement • Religious freedom • Political freedom • Wars • Environmental refugees

44. Case Study: The United States: A Nation of Immigrants • Historical role of immigration in the U.S. • Legal immigration • Illegal immigration • Controversy over immigration policy

45. Legal Immigration to the U.S. between 1820 and 2006 Fig. 6-11, p. 135

46. 2,000 1,800 1,600 1907 1,400 1914 New laws restrict immigration 1,200 Number of legal immigrants (thousands) 1,000 800 Great Depression 600 400 200 0 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2010 Year Fig. 6-11, p. 135

47. 6-3 How Does a Population’s Age Structure Affect Its Growth or Decline? • Concept 6-3 The numbers of males and females in young, middle, and older age groups determine how fast a population grows or declines.

48. Survivorship • Survivorship is the percentage of newborn individuals in a population that can be expected to survive to a given age. • It is used as another way to predict population trends. • To predict survivorship, demographers study a group of people born at the same time and notes when each member of the group dies.

49. Survivorship • The results of these studies are then plotted on a graph and might look like one of the types of survivorship graphs below.

50. Survivorship • Wealthy developed countries such as Japan and Germany currently have a Type I survivorship curve because most people live to be very old. • Type II populations have a similar death rate at all ages. • Type III survivorship is the pattern in very poor human populations in which many children die. • Both Type I and Type III may result in populations that remain the same size or grow slowly.