The Human Population and Its Impact

1. The Human Population and Its Impact Chapter 6

2. Core Case Study: Are There Too Many of Us? (1) • Estimated 2.4 billion more people by 2050 • Are there too many people already? • Will technological advances overcome environmental resistance that populations face? • Should populations be controlled?

3. Core Case Study: Are There Too Many of Us? • Will growing populations cause increased environmental stresses? • Infectious diseases • Biodiversity losses • Water shortages • Traffic congestion • Pollution of the seas • Climate change

4. 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 for humans and many other species.

6. Human Population Growth Continues but It Is Unevenly Distributed • 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

7. Human Population Growth Continues but It Is Unevenly Distributed (2) • Population growth in developing countries is increasing 15 times faster than developed countries • By 2050, 97% of growth will be in developing countries • Should the optimum sustainable population be based on cultural carrying capacity?

8. MI L L I O NS

9. Population Projections Over 95% of this increase will take place in “Developing Countries”

11. Current World Population • Population ClockVital Events (per time unit) Global population was 6,901,260,547US population- 310,859,059 On Feb. 20th 2011at 9:30 pm • The global population grows by: • Nearly 2.4persons per second • Nearly 8,607 persons per hour • Over 206,563 persons per day • Over 75 million persons per year

12. How Much is a Billion? • 1,000 seconds = 16.7 minutes • 1 million-s = 16,677 min = 11.6 days • 1 billion-s = 11,574 days = 31.7 years • 1,000 pennies = ~ 88 ounces = 5.5 pounds • 1 million pennies = 5,500 pounds (~1-Suburban) • 1 billion pennies = 2,750 tons (~2 Space Shuttles)

13. Billion Grains of Rice • 200 grains of rice in a teaspoon • 9,600 grains of rice in a cup (48 tsp) • How many Cups are in a Gallon? • 16 cups • How many grains of rice are in 16 cups? • 9,600 x 16 = 153,600 grains of rice • How many gallons would it take to take to equal 1 million grains of rice? • 1,000,000 divided by 153,600 = • 6.5 Gallons = 1 million grains of rice

14. If 6.5 gallons equal 1 million how many gallons would it take to equal 1 billion? • 6.5 gallons x 1000 = • 6,500 gallons = 1 billion • How many gallons would it take to equal 6.6 billion? • 42,900 gallons of rice = 6.6 billion grains of rice.

15. Science Focus: How Long Can the Human Population Keep Growing? • Thomas Malthus and population growth: 1798 • Humans have altered 83% of the earth’s land surface • Can the human population grow indefinitely?

16. 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.

17. 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- # births / 1000 population • Crude death rate- # deaths / 1000 population

20. Rates of Global Pop. Changeuse: International Data Base http://www.census.gov/ipc/www/idbnew.html, then Online Demographic Aggregation • CBR (crude birth rate) = # births / 1000 population 1990: 24 now: 20.6 • CDR (crude death rate) = # deaths / 1000 population 1990: 9 now: 8.8

21. Growth Rate = (b + i) – (d + e) 1990: 1.5% now: 1.19% • growth rates have come down • Annual rate of Natural Population change % = (BR – DR/1000) x 100 • (BR-DR)/10

22. Rule of 70 • How long does it take to double? • Resource use • Population size • Money in a savings account • Rule of 70 • 70 divided by the percentage growth rate = doubling time in years • 70 / 7% means it takes ten years to double Homework: YouTube- rule of 70- Albert Bartlett “Most important video you will ever see” 9 min.

23. Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population • Replacement fertility rate (RFR) • The number of children a couple must have to replace their parents • A RFR of 2.1 for developed countries with low infant and child mortality rates • Africa RFR = 2.5 • Total fertility rate (TFR) • The average number of children born to a woman • Average in developed countries = 1.5 • Average in developing countries = 3.8 • Worldwide 1990: 3.1 now: 2.76

25. Total Fertility Rates for US 4.0 3.5 3.0 2.5 Births per woman 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

26. Case Study: The U.S. Population Is Growing Rapidly • Drop in TFR in U.S. • Rate of population growth has slowed • Population still growing and not leveling off • Fourfold increase since 1900 • Changes in lifestyle in the U.S. during the 20th century

27. Several Factors Affect Birth Rates and Fertility Rates • 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

28. Several Factors Affect Birth Rates and Fertility Rates • Infant mortality rate • 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

29. 47 years Life expectancy 77 years 8% Married women working outside the home 81% 15% High school graduates 83% 10% Homes with flush toilets 98% 2% Homes with electricity 99% 10% Living in suburbs 52% 1900 $3 Hourly manufacturing job wage (adjusted for inflation) 2000 $15 1.2 Homocides per 100,000 people 5.8

30. Several Factors Affect Death Rates • Life expectancy • Average # of years a newborn canexpect to live • Infant mortality rate (IMR) • infant deaths per 1000 live births (infant < 1 yr) • Why are people living longer and fewer infants dying? • Increased food supply and distribution • Better nutrition • Medical advances • Improved sanitation

31. Several Factors Affect Death Rates (2) • 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

32. http://www.povertymap.net/pub/mipwa/sections/w-global/health-sanit/infant-mortality-2.htmhttp://www.povertymap.net/pub/mipwa/sections/w-global/health-sanit/infant-mortality-2.htm

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

34. Case Study: The United States: A Nation of Immigrants • Historical role of immigration in the U.S. • Opportunity for the world’s poor and oppressed • Since 1820, the U.S. has admitted almost twice as many immigrants and refugees as all other countries combined • Legal immigration • Illegal immigration • Legal and illegal immigration accounts for 40% of the country’s annual population growth

36. 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.

37. Population Pyramids • Graphic device: bar graph • shows the age and gender composition of a region • horizontal axis: gender • male: left-hand female: right-hand • absolute number of people or % • vertical axis: age groups • Pre-reproductive ages = birth –14 years of age • Reproductive ages= 15 –44 years of age • Post reproductive ages = 45 & up

38. Population Pyramid with young cohorts

39. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Austria or Italy

41. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Austria or Italy

43. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Austria or Italy

45. Population Pyramids • Population Pyramids on the Web • High Growth: Afghanistan • Moderate Growth: Mexico • Zero Growth: U.S. • Negative Growth: Italy

47. We Can Use Age-Structure Information to Make Population and Economic Projections • Baby boomers • Job market when they retire

48. Influencing Population SizeAge Structure & Population Projections • Baby boomers - half of U.S. population; use most of goods and services; make political and economic decision • baby-bust generation - born since 1965; may have to pay more income, health care and social security to support retired baby boomers; but face less job competition • Better health may --> later retirement of baby boomers --> keep high-salary jobs

49. Tracking the baby-boom generation in the United States

50. Populations Made Up of Mostly Older People Can Decline Rapidly • Slow decline • Manageable • Rapid decline • Severe economic problems • Severe social problems