ENVIRONMENTAL SCIENCE

1. 13e ENVIRONMENTALSCIENCE CHAPTER 6:The Human Population and Urbanization

2. Core Case Study: Are There Too Many of Us? (1) • 6.8 billion people • 82 million more each year • 2050: 9.5 billion people at current growth rates • Most growth in low-income and middle-income countries • Enough resources for growing population?

3. Core Case Study: Are There Too Many of Us? (2) • Negative viewpoint • 20% currently lack basic necessities • Declining conditions increase death rate • Increased resource use • Increased environmental degradation • Positive viewpoint • Technological solutions will increase carrying capacity • Growing population a valuable resource

4. Fig. 6-1, p. 94

5. 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.

6. Human Population Explosion • Exponential growth (J-curve) in past 200 years • Three major reasons • Ability to expand into diverse habitats • Emergence of agriculture • Sanitation systems and control of infectious diseases decreased death rates

7. How Long Can the Human Population Grow • Rate slowing, but still exponential • Uneven global growth • No population can grow indefinitely • 2050: 9.5 billion people at current growth rates • Most growth in developing countries, least likely to cope

8. Fig. 1-10, p. 16

9. 13 12 11 10 9 8 7 6 5 4 3 2 1 0 ? Industrial revolution Black Death—the Plague 2-5 million years 8000 6000 4000 2000 2000 2100 B.C. A.D. Hunting and gathering Agricultural revolution Industrial revolution Fig. 1-1, p. 1 Fig. 1-10, p. 16

10. Fig. 6-2, p. 96

11. 12 High 10.8 11 10 Medium 9.5 9 8 Population (billions) 7 Low 7.8 6 5 4 3 2 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year Fig. 6-2, p. 96

12. Supplement 3, Fig. 4, p. S8

13. Supplement 2, Fig. 3, p. S4

14. Supplement 3, Fig. 5, p. S9

15. Supplement 3, Fig. 6, p. S9

16. Supplement 3, Fig. 7, p. S10

17. Fig. 6-3, p. 97

18. Natural Capital Degradation Altering Nature to Meet Our Needs Reduction of biodiversity Increasing use of the earth's net primary productivity Increasing genetic resistance of pest species and disease-causing bacteria Elimination of many natural predators Introduction of potentially harmful species into communities Using some renewable resources faster than they can be replenished Interfering with the earth's chemical cycling and energy flow processes Relying mostly on polluting and climate-changing fossil fuels Fig. 6-3, p. 97

19. 6-2 What Factors Influence the Size of the Human Population? • Concept 6-2A Population size increases through 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 the population size.

20. Population Change • Population change = (births + immigration) - (deaths + emigration) • Demographers look at birth rates and death rates • 2009: • China, 1.3 billion people • India, 1.1 billion people • USA, 306 million people

21. Number of Children • Fertility rates affect population size and growth rate • Total fertility rate (TFR) • 1950-2009: Global TFR fell to: • 1.6 from 2.5 in developed countries • 2.8 from 6.5 in developing countries

22. Case Study: The U.S. Population Is Growing Rapidly • Quadrupled in 100 years, despite oscillations in TFR • Baby boom: High TFR • Current births outnumbering deaths and legal immigration • Growing faster than other developed countries • 2050 estimate: 439 million

23. Fig. 6-4, p. 98

24. 4.0 3.5 3.0 2.5 2.1 Births per woman 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 Fig. 6-4, p. 98

25. Fig. 6-5, p. 99

26. 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. 6-5, p. 99

27. 47 years Life expectancy 77 years 8% Married women working outside the home 81% High school graduates 15% 83% Homes with flush toilets 10% 98% Homes with electricity 2% 99% Living in suburbs 10% 52% Hourly manufacturing job wage (adjusted for inflation) $3 $15 Homicides per 100,000 people 1.2 5.8 Fig. 6-5, p. 99

28. 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. 6-5, p. 99

29. Factors Affecting Birth Rates (1) • Importance of children as part of labor force • Cost of raising and educating children • Availability of retirement systems • Urbanization • Educational and employment opportunities for women

30. Factors Affecting Birth Rates (2) • Average marriage age • Availability of legal abortion and reliable birth control methods • Religious beliefs, traditions, cultural norms

31. Factors Affecting Death Rates • Population growth is also response to decline in crude death rate • Life expectancy and infant mortality rate important indicators of overall health • Average life expectancy increased • Infant mortality – barometer of a society’s quality of life

32. Supplement 3, Fig. 8, p. S10

33. Supplement 3, Fig. 9, p. S11

34. Migration • Migration driven by economic desires • Other reasons • Religious persecution • Political oppression • Ethnic conflicts • Wars • Environmental degradation

35. Case Study: The United States - A Nation of Immigrants (1) • Immigration – legal and illegal – 39% population growth • 1820–1960: Most immigrants European • Since 1960 • Latin America – 53% • Asia – 25% • Europe – 14%

36. Case Study: The United States - A Nation of Immigrants (2) • Opponents of immigration • Stabilize population sooner • Reduce growing environmental impact • 60% of population favor reducing immigration • Proponents of immigration • Important historical role • Do menial jobs and pay taxes • Add cultural vitality • Replace retiring baby boomers

37. 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 populations grow or decline.

38. Age Structure • Distribution of population • Prereproductive • Reproductive • Postreproductive • Country with many young people grows rapidly • Country with many older people will decline • Developing countries: >30% under 15 years old

39. Fig. 6-6, p. 102

40. Fig. 6-6, p. 102

41. Fig. 6-7, p. 102

42. Age Structure Predicts the Future • 36% of U.S. population baby boomers • Graying of America • Over time: increasing percentage of older baby boomers • Changes the economy

43. Fig. 6-8, p. 103

44. Fig. 6-8, p. 103

45. Fig. 6-8, p. 103

46. Fig. 6-8, p. 103

47. Fig. 6-8, p. 103

48. 1955 1985 2015 2035 Stepped Art Fig. 6-8, p. 103

49. Declines Occur in Aging Populations • “Baby bust” or “birth dearth” – TFR below 1.5 children per couple • Labor shortages • Strain on governments for public services • Fewer taxpayers

50. Rising Death Rate: The AIDS Tragedy • Disrupts social and economic structure • Removes productive young adults • 1981-2008: 27 million deaths • Eight African countries: 16–39% infected adults • Life expectancy 30–40 years