1. Applying Population Dynamics: The Human Population and Its Impact
Chapter 6
Applying Population Dynamics:
The Human Population and Its Impact

2. Chapter Overview Questions
What is the history of human population growth, and how many people are likely to be here by 2050?
How is population size affected by birth, death, fertility, and migration rates?
How is population size affected by percentages of males and females at each age level?

3. Chapter Overview Questions (cont’d)
How can we slow population growth?
What success have India and China had in slowing population growth?
What are the major impacts of human activities on the world’s natural ecosystems?

4. Core Case Study: Is the World Overpopulated?
The world’s population is projected to increase from 7 billion to about 9.5 billion between 2011 and 2050.
The debate over interactions among population growth, economic growth, politics, and moral beliefs is one of the most important and controversial issues in environmental science.

5. Core Case Study: Is the World Overpopulated?
Much of the world’s population growth occurs in developing countries like China and India.
India 18%
China 22%
China + India = 40%
USA is #3 with 4.5%

6. Core Case Study: Is the World Overpopulated?
Some argue that the planet has too many people.
Some feel that the world can support billions of more people due to technological advances.
There is a constant debate over the need to reduce population growth.
Must consider moral, religious, and personal freedom.

7. Two Fundamental Questions…
WHY are living conditions so radically different between developed countries and undeveloped countries?
“Accidents of Geography”…read Jared Diamond’s Guns, Germs, & Steel”
WHY are population dynamics so different between developed countries and undeveloped countries?
3 Revolutions, Expansion into new ecosystems, and The Demographic Transition

8. Birth rate and death rate Relative population size
More on this later….
The Demographic Transition
Stage 1
Preindustrial
Stage 2
Transitional
Stage 3
Industrial
Stage 4
Postindustrial
High
Birth rate
Birth rate and death rate
(number per 1,00 per year)
Relative population size
Death rate
Figure 9.14
Generalized model of the demographic transition. There is uncertainty over whether this model will apply to some of today’s developing countries. QUESTION: At what stage is the country where you live?
Total population
Low
Low
Increasing
Very high
Decreasing
Low
Zero
Negative
Growth rate over time

9. HUMAN POPULATION GROWTH: A BRIEF HISTORY
The human population has grown rapidly because of
the expansion of agriculture and industrial production
expansion into new ecosystems
lower death rates from improvements in hygiene and medicine.
3 Revolutions!
Agricultural
Industrial-Medical
Info-Globalization

10. Agricultural Revolution
Before…

11. Agricultural Revolution
After… (but before the “green revolution”)

12. Agricultural Revolution
After…. (and after the “green revolution”)

13. Industrial-Medical Revolution
Before…

14. Industrial-Medical Revolution
After.

15. Industrial-Medical Revolution
Before…

16. Industrial-Medical Revolution
After.

17. GLOBAL HUMAN POPULATION GROWTH
10,000 years ago 5 million
billion
billion
billion
billion
billion
billion
billion
Currently:
Still increasing, but at a decreasing rate.
(Birth rates are still higher than death rates, but by a lesser and lesser amount)

18. GLOBAL HUMAN POPULATION GROWTH: A BRIEF HISTORY
In 2008:
Still growing exponentially at 1.22% =
82 million people added/yr =
225,000 per day =
2.4 people every time your heart beats!

19. Where Are We Headed?
We do not know how long we can continue increasing the earth’s carrying capacity for humans.
There are likely to be between billion people on earth by 2050 (mean probability of 9.5 billion).
97% of growth will be in developing countries among people living in acute poverty.
Which leads to the question…

20. Where Are We Headed?
What is the optimum sustainable population of the earth based on the cultural carrying capacity?
Thomas Malthus Proposed that human populations will crash because agricultural production increases linearly, while population increases exponentially.
So far, Malthus was “wrong”, because he did not forsee the exponential increase in food supply due to genetic & technical advances in agriculture.

21. Where Are We Headed?
U.N. world population projection based on women having an average of 2.5 (high), 2.0 (medium), or 1.5 (low) children.
(Total Fertility Rate)
Next

22. Total Fertility Rate High (2.5) High 10.7 Medium (2.0) Low (1.5)
9.3
Population (billions)
Low
7.8
Figure 9.2
Global connections: UN world population projections, assuming that by 2050 women have an average of 2.5 children (high), 2.0 children (medium), or 1.5 children (low). The most likely projection is the medium one—8.9 billion by (Data from United Nations, World Population Prospects: The 2001 Revision, 2002)
Year
Fig. 9-2, p. 173

23. FACTORS AFFECTING HUMAN POPULATION SIZE
Population increases because of births and immigration and decreases through deaths and emigration.
Instead of using raw numbers, crude birth rates and crude death rates are used (based on total number of births or deaths per 1,000 people in a population).

24. Average crude birth rate Average crude death rate1
Average crude birth rate
Average crude death rate 21 20
World 9 8
2011?
All developed
countries 11 10
All developing
countries 23
Figure 9.3
Global connections: average crude birth and death rates for various groupings of countries in (Data from Population Reference Bureau)
Why? 8
Developing
countries
(w/o China) 27 9
2006 data
Fig. 9-3, p. 174

25. 2011? 2006 data 36 Africa 12 Latin and 18 Central America 6 18 Asia 738 15 12
Latin and
Central America 21 18 6 6 18
Asia 20 7 7
Oceania 17 18 7
2011? 7
United
States 13 14
Figure 9.3
Global connections: average crude birth and death rates for various groupings of countries in (Data from Population Reference Bureau) 8 8
North
America 14 13 8 8
Europe 11 10 11 11
2006 data
Fig. 9-3, p. 174

26. Declining Fertility Rates: Fewer Babies per Women
Fertility is the number of babies one woman has in her lifetime.

27. Declining Fertility Rates: Fewer Babies per Women
Total Fertility Rate (TFR) is the average number of babies born per woman, per region.

28. Declining Total Fertility Rates: Fewer Babies per Women
The average number of children that a woman bears has dropped sharply.
This decline is not low enough to stabilize the world’s population in the near future.
Replacement-level fertility a.k.a. “ZPG”: the number of children an average couple must bear to replace themselves.
Total fertility rate (TFR): the average number of children a woman has during her reproductive years (average per region)
What should global TFR be in order to achieve ZPG?

29. Declining Fertility Rates: Fewer Babies per Women
The replacement level TFR to sustain a population (attain ZPG) is :
2.1 children in the developed world
2.5 children in the developing world (why?)
In 2008, the average global Total Fertility Rate was 2.6 children per woman.
1.6 in developed countries (down from 2.5 in 1950).
2.8 in developing countries (down from 6.5 in 1950).

30. Case Study: Fertility and Birth Rates in the United States
million – 312 million
Nearly 2.9 million people were added to the U.S. in 2008:
66% occurred because of births outnumbering deaths.
34% came from illegal and legal immigration.

31. Case Study: Fertility and Birth Rates in the United States
In 2008, the total fertility rate in the United States was 2.1
Next

32. U.S. Total Fertility Rate
Births per woman
Replacement
Level
Baby boom
(1946–64)
Figure 9.5
Total fertility rates for the United States between 1917 and Use this figure to trace changes in total fertility rates during your lifetime. QUESTION: How many children do you plan to have? (Data from Population Reference Bureau and U.S. Census Bureau)
Year
Fig. 9-5, p. 175

33. Case Study: Fertility and Birth Rates in the United States
The baby bust that followed the baby boom was largely due to delayed marriage, contraception, and abortion.
Next

34. Does this graph represent a stock concept or a flow concept?
U.S. Crude Birth Rate
1910 to 2010
End of World War II
Births per thousand population
Demographic transition: Transitional Stage to Industrial Stage
Depression
Baby boom
Echo baby boom
Baby bust
Figure 9.6
Birth rates in the United States, 1910–2006. Use this figure to trace changes in crude birth rates during your lifetime. (Data from U.S. Bureau of Census and U.S. Commerce Department)
Year
Does this graph represent a stock concept or a flow concept?
Fig. 9-6, p. 175

35. The Times, They are a Changin’
In 1905, in the US:
The 3 leading causes of death were pneumonia, tuberculosis, & diarrhea
90% of doctors had no college education
1/5 of adults could not read or write
Average $ was 22 cents / hour, $ / year
A total of 9000 cars
A total of 144 miles of paved roads
A 3 min. call from Denver to NYC cost $11
The population of Las Vegas was 30 people
Most women washed their hair once a month

36. Key (USA) 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%
Homes with
electricity 2%
99%
Living in
suburbs
10%
Key
Figure 9.7
Some major changes that took place in the United States between 1900 and QUESTION: Which two of these changes do you think were the most important? (Data from U.S. Census Bureau and Department of Commerce)
52%
1900
Hourly manufacturing job wage (adjusted for inflation) $3
2000
$15
(USA)
Homicides per
100,000 people
1.2
5.8
Fig. 9-7, p. 176

37. Factors Affecting Birth Rates and Fertility Rates
Direction of influence?
The number of children women have is affected by:
The cost of raising and educating them.
Availability of pensions.
Urbanization.
Education and employment opportunities.
Infant deaths.
Marriage age.
Availability of contraception and abortion.

38. Factors Affecting Death Rates
Death rates have declined because of:
Increased food supplies, better nutrition.
Improved sanitation and personal hygiene.
Safer water supplies.
Advances in medicine.

39. Factors Affecting Death Rates
U.S. infant mortality is twice that of any other industialized nation (ranked 46th world-wide) due to:
Inadequate pre- and post-natal care for poor women & children
Drug addiction.
High teenage birth rate.

40. Case Study: U.S. Immigration
Since 1820, the U.S. has admitted almost twice as many immigrants and refugees as all other countries combined.
Next

41. Number of legal immigrants (thousands)
1907
1914
New laws
restrict
Immigration
Number of legal immigrants (thousands)
Great
Depression
Figure 9.8
Legal immigration to the United States, 1820–2003. The large increase in immigration since 1989 resulted mostly from the Immigration Reform and Control Act of 1986, which granted legal status to illegal immigrants who could show they had been living in the country for several years. (Data from U.S. Immigration and Naturalization Service and the Pew Hispanic Center)
Year
Fig. 9-8, p. 178

42. POPULATION AGE STRUCTURE
The number of people in young, middle, and older age groups determines how fast populations grow or decline.

43. POPULATION AGE STRUCTURE
The number of people younger than age 15 is a major factor determining a country’s population growth.
“Perhaps the world’s most important population statistic: 28% of the world’s population (in 2008) was under 15 years old.”
Developed countries: 17%
Developing countries: 30% (41% in Africa)
1.9 billion about to enter their reproductive years!
In parts of Asia, Africa, & South America,
20-50% of the age group is unemployed.
What are the implications of this statistic for terrorism?

44. POPULATION AGE STRUCTURE
A population with a large proportion of its people in the preproductive ages 1-14 has a large potential for rapid population growth.
Next

45. Age Structure Diagrams
Male
Female
Male
Female
Male
Female
Male
Female
Expanding Rapidly
Guatemala
Nigeria
Saudi Arabia
Expanding Slowly
United States
Australia
Canada
Stable
Spain
Portugal
Greece
Declining
Germany
Bulgaria
Italy
Figure 9.9
Generalized population age structure diagrams for countries with rapid (1.5–3%), slow (0.3–1.4%), zero (0–0.2%), and negative population growth rates (a declining population). Populations with a large proportion of its people in the prereproductive ages of 1–14 (at left) have a large potential for rapid population growth. QUESTION: Which of these diagrams best represents the country where you live? (Data from Population Reference Bureau)
Reproductive ages
15–44
Postreproductive ages
45–85+
Prereproductive ages
0–14
Fig. 9-9, p. 179

46. 2009 US Life Expectancy At Birth:
US Census Bureau Data
Year 2000 Census
2009 US Life Expectancy At Birth:
Male 75 yrs
Female 82 yrs
Figure 9.11
Tracking the baby-boom generation in the United States. (Data from Population Reference Bureau and U.S. Census Bureau)
2011: 80 yrs
Fig. 9-11, p. 180

47. POPULATION AGE STRUCTURE
About 30% of the people in developing countries were under 15 years old in 2008
versus only 17% in developed countries.
Next

48. Developed Countries Male Female Age Population (millions)
Figure 9.10
Global connections: population structure by age and sex in developing countries and developed countries, (Data from United Nations Population Division and Population Reference Bureau)
Population (millions)
Fig. 9-10a, p. 179

49. Developing Countries Male Female Age Population (millions)
Figure 9.10
Global connections: population structure by age and sex in developing countries and developed countries, (Data from United Nations Population Division and Population Reference Bureau)
Population (millions)
Fig. 9-10b, p. 179

50. POPULATION AGE STRUCTURE
Today, baby boomers make up nearly half of all adult Americans and dominate the populations demand for goods and services.
Next

51. Follow the Boomers! 1955 1985 2015 2035 Age Age Age Age Females Males
Figure 9.11
Tracking the baby-boom generation in the United States. (Data from Population Reference Bureau and U.S. Census Bureau)
1955
1985
2015
2035
Fig. 9-11, p. 180

52. POPULATION AGE STRUCTURE
Changes in the distribution of a country’s age groups have long-lasting economic and social impacts.
Baby boomers wield a lot of influence…how will they use this when they are all old?
Large numbers of baby boomers in upper management may prevent baby busters from advancing in corporations
Baby busters will not have a lot of competition among each other for getting jobs, and may eventually be able to command high wages.
Assuming many jobs have not been exported

53. POPULATION AGE STRUCTURE: Decreasing Population
About 14% of the world’s population live in countries with stabilizing or declining populations.
Rapid population decline can lead to long-lasting economic and social problems.

54. Aging populations… • Can threaten economic growth
• Less government revenues with
fewer workers
• Less entrepreneurship and new
business formation
• Less likelihood for new technology development
• Increasing public deficits to fund higher pension and healthcare costs
Figure 9.13
Some problems with rapid population decline. QUESTION: Which three of these problems do you believe are the most important?
Fig. 9-13, p. 182

55. POPULATION AGE STRUCTURE
Death from AIDS can disrupt a country’s social and economic structure by removing significant numbers of young adults.
Doctors? Nurses? Teachers? Physical Labor?
Global aging may help promote peace
Fewer young people for military service
Parents w/ 1 to 2 kids less likely to support war
Less govt. funds available for military due to rising health care and pension costs

56. POPULATION AGE STRUCTURE
Global age structure predictions based on a medium fertility projection.
The cost of an aging population will strain the global economy.
What changes will this precipitate?
Next

57. Age Distribution (%) Year Under age 15 Age 60 or over Age 80 or over
Figure 9.12
Global aging. Projected percentage of world population under age 15, age 60 or over, and age 80 or over, 1950–2150, assuming the medium fertility projection shown in Figure 9-2. The cost of supporting a much larger elderly population will place enormous strains on many nations and the global economy. (Data from the United Nations)
Year
Under age 15
Age 60 or over
Age 80 or over
Fig. 9-12, p. 181

58. SOLUTIONS: INFLUENCING POPULATION SIZE
Demographic Transition: As countries become economically developed, their birth and death rates tend to decline.
Preindustrial stage: little population growth due to high infant mortality & crude death rate.
Transitional stage: industrialization begins, death rates drops and birth rates remain high.
Industrial stage: birth rate drops and approaches death rate.
Postindustrial stage : birth & death- low & equal

59. SOLUTIONS: INFLUENCING POPULATION SIZE
Generalized model of demographic transition.
Some developing countries may have difficulty making the demographic transition.
Figure 9-14

60. The Demographic Transition
Stage 1
Preindustrial
Stage 2
Transitional
Stage 3
Industrial
Stage 4
Postindustrial
High
Birth rate
(number per 1,000 per year)
Birth rate and death rate
Relative population size
Death rate
Figure 9.14
Generalized model of the demographic transition. There is uncertainty over whether this model will apply to some of today’s developing countries. QUESTION: At what stage is the country where you live?
Total population
Low
Low
Increasing
Very high
Decreasing
Low
Zero
Negative
Growth rate over time
Fig. 9-14, p. 183

61. SOLUTIONS: INFLUENCING POPULATION SIZE
Family planning has been a major factor in reducing the number of births and abortions throughout most of the world.

62. SOLUTIONS: INFLUENCING POPULATION SIZE
Women tend to have fewer children if they are:
Educated.
Hold a paying job outside the home.
Do not have their human right suppressed.

63. SOLUTIONS: INFLUENCING POPULATION SIZE
The best way to slow population growth is a combination of:
Investing in family planning.
Reducing poverty.
Elevating the status of women.
(Globally, women own less than 2% of the land)
Microfinance has become a leading tool in these efforts world-wide.

64. Microfinance Invented by Dr. Muhammad Yunus Born in Bangladesh
1971: PhD in economics from Vanderbilt University
1976- Loaned $27 to 42 women, who turned a profit, then founded Grameen Bank
2006: Nobel Peace Prize

65. According to the journal MicroBanking Bulletin, at the end of 2006 it was tracking 704 MFIs that were serving 52 million borrowers ($23.3 billion in outstanding loans) and 56 million savers ($15.4 billion in deposits). Av. loan = $450
Of these clients, 70% were in Asia, 20% in Latin America and the balance in the rest of the world.[21]

66. Because many women from one village borrow individual loans at the same time, they encourage each other to keep going when challenges arise.

67. The repayment % rate for most MFIs is in the high nineties, exceeding that of any large bank in the world.

68. SLOWING POPULATION GROWTH IN INDIA AND CHINA
For more than five decades, India has tried to control its population growth with only modest success.
Since 1970, China has used a government-enforced program to cut its crude birth rate in half and sharply reduce its fertility rate.

69. India’s Failed Family Planning Program
Well intentioned, but very idealistic
Poor planning.
Bureaucratic inefficiency.
Low status of women.
Extreme poverty.
Lack of administrative financial support.
Disagreement over the best ways to slow population growth.
Recent economic development may finally make it possible for India to begin to reduce it’s TFR

70. China’s Family Planning Program
Currently, China’s TFR is 1.6 children per women.
Encouraging later marriages
Urging families to only have one child
Health, pension, & employment benefits for 1-child families
Encouraging contraception & family planning
Providing free birth control & abortions

71. China’s Family Planning Program
China has moved 300 million people out of poverty.
Problems:
Strong male baby preference leads to gender imbalance.
Average population age is increasing.
Still not enough resources to support China’s huge population.

72. HUMAN ASPECTS ON NATURAL SYSTEMS
Excluding Antarctica, human activities have affected about 83% of the earths land surface.
Next

73. Human-Dominated Systems Property
Natural
Systems
Human-Dominated Systems
Property
Complexity
Energy source
Waste production
Nutrients
Net primary productivity
Biologically diverse
Renewable solar energy
Little, if any
Recycled
Shared among many species
Biologically simplified
Mostly nonrenewable fossil fuel energy
High
Often lost or wasted
Majority used, destroyed, or degraded to support human activities
Figure 9.16
Some typical characteristics of natural and human-dominated systems. Many human activities threaten local ecological processes and some bring about harmful regional and global changes.
Fig. 9-16, p. 188

74. HUMAN ASPECTS ON NATURAL SYSTEMS
We have used technology to alter much of the rest of nature in ways that threaten the survival of many other species and could reduce the quality of life for our own species.
Next

75. 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
Deliberate or accidental 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 non-renewable, polluting fossil fuels
Figure 9.17
Natural capital degradation: major ways humans have altered the rest of nature to meet our growing population, needs, and wants. QUESTIONS: Which three of these items do you believe have been the most harmful? How does your lifestyle contribute directly or indirectly to each of these items?
Fig. 9-17, p. 188