Human population growth

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• Human population growth

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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

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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
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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.

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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
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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
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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
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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.

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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
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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
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Demography

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

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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
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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
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Population density and distribution

• Humans are unevenly distributed, living at
  different densities from region to region.

Figure 7.8
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Age structure

• Age structure can influence population growth
  rates.

Figure 7.9
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Age structure Age pyramids

• Canada (left) has a much slower growing
  population than does Madagascar (right).

Figure 7.10
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Age structure Graying populations

• Demographers project that Chinas population will
  become older over the next two decades.

Figure 7.11a,b
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Age structure Graying populations

• Chinas aging population will mean fewer
  working-age citizens to finance social services
  for retirees.

Figure 7.11c
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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
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Sex ratios

• A populations sex ratio can affect its growth
  rate.

Figure 7.13
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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

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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
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Natural rate of population change

• Change due to birth and death rates alone,
  excluding migration
• Is often expressed in per year

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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.

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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
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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.

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Total fertility rates by region

• African nations have the highest TFRs.
• European nations have the lowest TFRs.

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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

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Demographic transition Stages
Figure 7.18
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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.

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Female education and TFR

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

Figure 7.16
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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
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Family planning and TFR

• Nations that invested in family planning (green)
  reduced TFRs more than similar nations that did
  not (red).

Figure 7.17a
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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
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HIV/AIDS and human population

• AIDS cases are increasing rapidly worldwide.

Figure 7.26
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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
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Poorer countries will experience most future
population growth

• 98 of the next billion people born will live in
  developing nations.

Figure 7.20
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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
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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.

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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

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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
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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
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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?

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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.

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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.

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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.

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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
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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.

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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

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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.

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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.

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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

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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
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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