The Human Population and Its Impact

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The Human Population and Its Impact

• Chapter 6

Thousands of people crowd onto a bathing beach to
avoid the summer heat in Dalian, northeast
China's Liaoning Province Picture REUTERS
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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?
• 7 Billion, National Geographic Magazine YouTube
• 7 Billion Are You Typical? -- National
  Geographic Magazine YouTube
• 7 Billion How Did We Get So Big So Fast? -
  YouTube

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Core Case Study Are There Too Many of Us? (2)

• Will growing populations cause increased
  environmental stresses?
• Infectious diseases
• Biodiversity losses
• Water shortages
• Traffic congestion
• Pollution of the seas
• Climate change

Support for overfishing? By Jovana Ruzicic,
Former EWG Press Secretary enviroblog.org
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(No Transcript)
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Crowded Street in China
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6-1 How Many People Can the Earth Support?

• Concept 6-1 We do not know how long we can
  continue increasing the earths carrying capacity
  for humans without seriously degrading the
  life-support system for humans and many other
  species.

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Human Population Growth Continues but It Is
Unevenly Distributed (1)

• 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

Worlds population still growing at rate of
1.22 per year Unevenly distributed
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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?
• The optimum level that would allow most people to
  live in reasonable comfort freedom w/o
  impairing ability of planet to sustain future
  generations. Aka Optimum Sustainable Population

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Global Connections UN World Population
Projections by 2050
Global connections UN world population
projections, assuming that by 2050 women will
have an average of 2.5 children (high), 2.0
children (medium), or 1.5 children (low). The
most likely projection is the medium one9.3
billion by 2050. (Data from United Nations).
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Science Focus How Long Can the Human Population
Keep Growing?

• Thomas Malthus and population growth 1798
• Hypothesized that human population tends to
  increase exponentially while food supplies tend
  to increase more slowly
• Humans have altered 83 of the earths land
  surface
• Can the human population grow indefinitely?

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Natural Capital Degradation Altering Nature to
Meet Our Needs
Major ways in which humans have altered the rest
of nature to meet our growing populations
resource needs and wants. Questions Which three
of these items do you believe have been the most
harmful? Explain.
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Animation Current and projected population sizes
by region
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Video Bonus for a baby
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Video People explosion
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Animation Resources depletion and degradation
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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.

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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 - of live births per 1,000
  people in a population in a given year
• Crude death rate

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Global Connections The Worlds 10 Most Populous
Countries in 2008
Global connections the worlds 10 most populous
countries in 2008, with projections of their
population sizes in 2025. (Data from World Bank
and Population Reference Bureau)
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Women Having Fewer Babies but Not Few Enough to
Stabilize the Worlds Population

• Fertility rate
• Replacement-level fertility rate average of
  children couples in a population must bear to
  replace themselves
• 2.1 in developed countries
• 2.5 in developing countries
• Total fertility rate (TFR) average of
  children born to women in a population during
  their reproductive years
• 2008 global TFR 2.6
• 1.6 in developed countries (2.5 in 1950)
• 2.8 in developing countries (6.5 in 1950)

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Case Study The U.S. Population Is Growing Rapidly

• Drop in TFR in U.S.
• Rate of population growth has slowed but
  population still growing faster than any other
  developed nation
• Population still growing and not leveling off
• Fourfold increase since 1900
• Changes in lifestyle in the U.S. during the 20th
  century p.127

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Stepped Art
Fig. 6-6, p. 128
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TFR Rates for the U.S. between 1917 and 2008
Total fertility rates for the United States
between 1917 and 2008. Question The U.S.
fertility rate has declined and remained at or
below replacement levels since 1972, so why is
the population of the United States still
increasing? (Data from Population Reference
Bureau and U.S. Census Bureau)
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Birth Rates in the U.S. from 1910 to 2008
Birth rates in the United States, 19102008. 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)
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Several Factors Affect Birth Rates and Fertility
Rates (1)

• 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

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Several Factors Affect Birth Rates and Fertility
Rates (2)

• 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

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Several Factors Affect Death Rates (1)

• Life expectancy average of 68 years globally
• Infant mortality rate - of children per 1,000
  births who die before age 1
• Life expectancy infant mortality rate are
  useful indicators of overall health of people in
  a country or region
• Why are people living longer and fewer infants
  dying?
• Increased food supply and distribution
• Better nutrition
• Medical advances
• Improved sanitation

Dr. Susan Dulkerian tends to a baby in the NICU
of Mercy Hospital. Part cbsnews.com
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Several Factors Affect Death Rates (2)

• U.S. infant mortality rate (165 in 1900 6.6 in
  2008) still high due to
• Inadequate health care for poor women during
  pregnancy and their infants
• Drug addiction among pregnant women
• High birth rate among teenagers

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Migration Affects an Areas Population Size

• Economic improvement
• Religious freedom
• Political freedom
• Wars
• Environmental refugees

motherjones.com
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Case Study The United States A Nation of
Immigrants

• Historical role of immigration in the U.S.
• Legal immigration
• Illegal immigration

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Legal Immigration to the U.S. between 1820 and
2003
Legal immigration to the United States, 18202003
(the last year for which data are available). 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)
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6-3 How Does a Populations 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.

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Populations Made Up Mostly of Young People Can
Grow Rapidly

• Age structure categories
• Prereproductive ages (0-14)
• Reproductive ages (15-44)
• Postreproductive ages (45)

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Generalized Population Age Structure Diagrams
Generalized population age structure diagrams for
countries with rapid (1.53), slow (0.31.4),
zero (00.2), and negative (declining)
population growth rates. A population with a
large proportion of its people in the
prereproductive age group (far left) has a large
potential for rapid population growth. (Data from
Population Reference Bureau)
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Population Structure by Age and Sex in Developing
and Developed Countries
Global outlook population structure by age and
sex in developing countries and developed
countries, 2006. Question If all girls under 15
had only one child during their lifetimes, how do
you think these structures would change over
time? (Data from United Nations Population
Division and Population Reference Bureau)
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We Can Use Age-Structure Information to Make
Population and Economic Projections

• Baby boomers added 79 million people to US
  population (1946-1964)
• Job market when they retire
• In 2011 first baby boomers turned 65
• Retirement could lead to shortage of workers
  unless replaced by automation and/or immigration
• Boomers have large political clout but could be
  lessened by immigration and echo baby boom
  (thats you!!)

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Tracking the Baby-Boom Generation in the United
States
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Populations Made Up of Mostly Older People Can
Decline Rapidly

• Slow decline
• Manageable
• Rapid decline
• Severe economic problems
• Severe social problems

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Populations Can Decline from a Rising Death Rate
The AIDS Tragedy

• 25 million killed by 2008
• Many young adults die
• loss of most productive workers
• Sharp drop in life expectancy
• International community called upon to
• Reduce the spread of HIV through education and
  health care
• Financial assistance and volunteers

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Active Figure Examples of age structure
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6-4 How Can We Slow Human Population Growth?

• Concept 6-4 Experience indicates that the most
  effective ways to slow human population growth
  are to encourage family planning, to reduce
  poverty, and to elevate the status of women.

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As Countries Develop, Their Populations Tend to
Grow More Slowly

• Demographic transition stages
• Preindustrial
• Transitional
• May lead to a demographic trap rapid population
  growth may outstrip economic growth and overwhelm
  local life support systems
• Industrial
• Postindustrial

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Stepped Art
Fig. 6-12, p. 134
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Planning for Babies Works

• Family Planning
• Responsible for a 55 drop in TFRs in developing
  countries
• Expansion of program
• Include teenagers, sexually active unmarried
  women, and men
• Slow and stabilize population growth
• Invest in family planning
• Reduce poverty
• Elevate the social and economic status of women

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Empowering Women Can Slow Population Growth

• Education
• Paying jobs
• Human rights without suppression
• For poor women the only holiday is when you are
  asleep

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Women from a Village in Burkina Faso Returning
with Fuelwood
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Case Study Slowing Population Growth in China
the One-Child Policy

• Encourages fewer children
• Gender imbalance
• Fast-growing economy
• Face serious resource and environmental problems

one-child policy China Digital Times
... chinadigitaltimes.net
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Case Study Slowing Population Growth in India

• Population control gender bias
• Poverty
• Malnutrition
• Environmental problems

Saroj Nagar Slum Nagpur The Orange city Nagpur
has 424 legal slum area's, ... walkthroughindia.co
m