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Human population growth

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Title: Human population growth


1
5
  • Human population growth

2
This lecture will help you understand
  • Human population growth
  • Demography
  • Affluence, technology, the status of women, and
    the environment
  • Population control programs
  • Demographic transition theory
  • Consumption and the ecological footprint
  • HIV/AIDS and human population

3
Key Words
age pyramid age structure AIDS epidemic demographi
c transition demography doubling time ecological
footprint family planning greater-than-exponential
growth rate human immunodeficiency
virus/acquired immunodeficiency syndrome
(HIV/AIDS) industrial stage IPAT model life
expectancy
population density population distribution populat
ion size post-industrial stage pre-industrial
stage replacement fertility sex ratio total
fertility rate (TFR) transitional stage
4
Central Case Chinas One-Child Policy
  • Unfettered population growth posed challenges for
    Chinas environment, economy, and political
    stability.
  • China tried to control its growth with a system
    of rewards and punishments to encourage one-child
    families.
  • The program decreased population growth, but
    meant government intrusion in private
    reproductive choices.

5
Baby Six Billion
  • The worlds population now exceeds 6 billion
    people.
  • The UN marked this symbolically by declaring a
    child born in 1999 in war-torn Sarajevo as the
    six-billionth baby.

Figure 7.1
6
World population has risen sharply
  • Global human population was lt1 billion in 1800.
  • Population has doubled just since 1963.
  • We add 2.5 people every second (79 million/year).

Figure 7.2
7
Population growth rates, 1990-1995
  • Growth rates vary from place to place.
  • Growth peaked at 2.1 in the 1960s it has now
    declined to 1.3.

Figure 7.3
8
Is population growth really a problem?
  • Some say NO
  • People can find or manufacture additional
    resources to keep pace with population growth.
  • Nations become stronger as their populations grow.
  • Some say YES
  • Not all resources can be replaced.
  • Even if they could, quality of life suffers.
  • Nations do not become stronger as their
    populations grow.

9
Modeling population and its consequences
  • Some models show population growth leading to
    resource depletion, which can result in declining
    food production, industrial output, and
    population.

Figure 7.4
10
Increasing our carrying capacity
  • Technology has allowed us to raise Earths
    carrying capacity for our species time and again.
  • Tool-making, agriculture, and industrialization
    each enabled humans to sustain greater
    populations.

Figure 7.5
11
Demography
  • Demography is the study of human populations.
  • Human populations exhibit the same fundamental
    characteristics as do populations of all other
    organisms.

12
Population size National populations
  • Nations vary from Chinas 1.3 billion down to
    Pacific island nations of 100,000.
  • Shown are the 15 most populous countries, and
    selected others 2002 data.

Figure 7.6
13
Population size Future projections
  • Demographers project population growth trends to
    estimate future population sizes.
  • Different fertility rate scenarios predict
    global population sizes in 2050 of 7.4 billion,
    8.9 billion, or 10.6 billion.
  • All these projections assume fertility rates
    below todays at todays rate, the population
    would reach 12.8 billion.

Figure 7.7
14
Population density and distribution
  • Humans are unevenly distributed, living at
    different densities from region to region.

Figure 7.8
15
Age structure
  • Age structure can influence population growth
    rates.

Figure 7.9
16
Age structure Age pyramids
  • Canada (left) has a much slower growing
    population than does Madagascar (right).

Figure 7.10
17
Age structure Graying populations
  • Demographers project that Chinas population will
    become older over the next two decades.

Figure 7.11a,b
18
Age structure Graying populations
  • Chinas aging population will mean fewer
    working-age citizens to finance social services
    for retirees.

Figure 7.11c
19
Age structure Baby booms
  • The United States baby boom is evident in age
    bracket 4050. U.S. age structure will change as
    baby boomers grow older.

Figure 7.12
20
Sex ratios
  • A populations sex ratio can affect its growth
    rate.

Figure 7.13
21
Factors affecting population growth rates
  • Population growth depends on rates of birth,
    death, immigration, and emigration.
  • (birth rate immigration rate)
  • (death rate emigration rate)
  • population growth rate

22
Migration can have environmental effects
  • Immigration and emigration play large roles
    today.
  • Refugees from the 1994 Rwandan genocide endured
    great hardship, and deforested large areas near
    refugee camps.

Figure 7.14
23
Natural rate of population change
  • Change due to birth and death rates alone,
    excluding migration
  • Is often expressed in per year

24
Chinas natural rate of change has fallen
  • Chinas rate has fallen with fertility rates. It
    now takes the population 4 times as long to
    double as it did 25 years ago.

25
Global growth rates have fallen
  • The annual growth rate of the world population
    has declined since the 1960s.
  • (But the population size is still rising!)

Figure 7.15
26
Fertility rates affect population growth rates
  • Total fertility rate (TFR) average number of
    children born per woman during her lifetime
  • Replacement fertility the TFR that keeps
    population size stable
  • For humans, replacement fertility is about 2.1.

27
Total fertility rates by region
  • African nations have the highest TFRs.
  • European nations have the lowest TFRs.

28
Demographic transition theory
  • Demographic transition model of economic and
    cultural change to explain declining death rates,
    declining birth rates, and rising life
    expectancies in Western nations as they became
    industrialized
  • Proposed by F. Notestein in the 1940s-1950s

29
Demographic transition Stages
Figure 7.18
30
Demographic transition Stages
  • The demographic transition consists of several
    stages
  • Pre-industrial stage high death rates and high
    birth rates
  • Transitional stage death rates fall due to
    rising food production and better medical care.
    Birth rates remain high, so population surges.
  • Industrial stage birth rates fall, as women are
    employed and as children become less economically
    useful in an urban setting. Population growth
    rate declines.
  • Post-industrial stage birth and death rates
    remain low and stable society enjoys fruits of
    industrialization without threat of runaway
    population growth.

31
Female education and TFR
  • Female literacy and school enrollment are
    correlated with total fertility rate
  • More-educated women have fewer children.

Figure 7.16
32
Family planning and TFR
  • Family planning, health care, and reproductive
    education can lower TFRs.
  • A counselor advises African women on health care
    and reproductive rights.

Figure 7.17b
33
Family planning and TFR
  • Nations that invested in family planning (green)
    reduced TFRs more than similar nations that did
    not (red).

Figure 7.17a
34
TFR decline in Bangladesh
  • Bangladesh reduced TFR from 7.1 to 4.6 in 25 yr,
    and is at 3.3 today.
  • Family planning, education, and outreach were
    responsible.

From The Science behind the Stories
35
HIV/AIDS and human population
  • AIDS cases are increasing rapidly worldwide.

Figure 7.26
36
HIV/AIDS and human population
  • Infects 1 in 5 people in southern African nations
  • Infects 5 million new people each year
  • Kills babies born to infected mothers
  • Has orphaned 14 million children
  • Has cut 15 years off life expectancies in parts
    of southern Africa

Figure 7.27
37
Poorer countries will experience most future
population growth
  • 98 of the next billion people born will live in
    developing nations.

Figure 7.20
38
Population and the environment
  • Population growth can lead to environmental
    degradation.
  • Overpopulation in Africas Sahel region has led
    to overgrazing of semi-arid lands.

Figure 7.21
39
Affluence and the environment
  • Poverty can lead to environmental degradation
  • BUT
  • wealth and resource consumption can produce even
    more severe and far-reaching environmental
    impacts.

40
The ecological footprint
  • The cumulative amount of Earths surface area
    required to provide the raw materials a person or
    a population consumes and to dispose of or
    recycle the waste that is produced

41
Ecological footprints
  • Residents of some countries consume more
    resourcesand thus use more landthan residents
    of others.
  • Shown are ecological footprints of an average
    citizen from various nations.

Figure 7.23
42
The wealth gap
  • Residents of developed nations have larger
    houses, more possessions, and more money than
    residents of developing nations.
  • The richest 20 of the worlds people consumes
    86 of its resources, and has gt80 times the
    income of the poorest 20.

Figure 7.25
43
Demographic fatigue and demographic transition
  • Many governments of developing countries are
    experiencing demographic fatigue, unable to
    meet the social, economic, and environmental
    challenges imposed by rapid population growth.
  • This raises the question
  • Will todays developing countries successfully
    pass through the demographic transition?

44
The IPAT model
  • Shows how Population, Affluence, and Technology
    interact to create Impact on our environment.
  • I P ? A ? T
  • Further factors can be added to the original
    equation of Holdren and Ehrlich to make it more
    comprehensive.

45
Conclusions Challenges
  • Human population is rising by 79 million people
    annually.
  • Many more people are born into poverty than into
    wealth.
  • Rich and poor nations are divided by a wealth
    gap.
  • HIV/AIDS is taking a heavy toll.
  • Population growth has severe environmental
    effects.

46
Conclusions Solutions
  • Expanding womens rights is crucial to encourage
    the demographic transition.
  • Health and reproductive education and counseling
    can reduce fertility rates.
  • Education, medicine, and policies can lessen the
    toll of HIV/AIDS.
  • New green technologies can help reduce
    population growths environmental impacts.

47
Viewpoints Population control?
Timothy Cline
Douglas Sylva
Access to reproductive health care, including
family planning, is a basic human right.
Governments do not have an interest in further
reducing fertility. Nor should they have the
authority to do so.
From Viewpoints
48
QUESTION Review
  • Using the I P ? A ? T equation, what would
    happen if the population doubled?
  • a. Affluence and technology would decline.
  • b. The environment would become more sensitive.
  • c. The environmental impact would double.
  • d. Nothing, because Earth can compensate.

49
QUESTION Review
  • What has allowed us to increase Earths carrying
    capacity for our species?
  • a. Agriculture
  • b. Industrialization
  • c. Tool-making
  • d. All of the above

50
QUESTION Review
  • Which statement is FALSE?
  • a. The global population growth rate is
    decreasing.
  • b. The global population is increasing.
  • c. At a TFR of 2.4, a human population grows.
  • d. Populations with age distributions skewed
    toward young people grow more slowly.

51
QUESTION Review
  • Women who are more educated tend to ?
  • a. Have higher TFRs.
  • b. Live in developing nations.
  • c. Have fewer children.
  • d. Contract HIV/AIDS.

52
QUESTION Weighing the Issues
  • Should the United States fund family planning
    efforts in other nations?
  • a. Yes, without reservation
  • b. Yes, in nations whose programs it approves
  • c. Only if it can influence the nations policies
  • d. Never under any circumstances

53
QUESTION Interpreting Graphs and Data
  • What happens during the transitional stage
    of the demographic transition?a. Birth rates
    rise death rates drop population increases
  • b. Birth rates drop death rates drop population
    decreases
  • c. Death rates drop birth rates are stable
    population increases

Figure 7.18
54
QUESTION Viewpoints
  • Do you believe that national governments should
    implement policies, subsidies, or other programs
    to reduce birth rates?
  • a. No, not at all
  • b. Yes, but only positive incentives for fewer
    children
  • c. Yespenalties for too many children
  • d. Yes, both incentives and penalties
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