The Human Population and Its Impact

1
The Human Population and Its Impact

• Chapter 6

2
Previous work

• Un Question chp 5
• Challenge question chp 5
• Lab completion

3
Current event questions 2

• 1) What is the main environmental point of the
  article?
• 2) What animal is at the center of the
  controversy? What role does this creature play in
  the ecosystem?
• 3) Is the government helping or hurting the
  situation?
• 4) What, in your opinion, are the actions that
  should be taken to solve the problem?

4

• Are there too many of us?

5
Core Case Study Are There Too Many of Us? (1)

• Estimated 2.4 billion more people by 2050
• What determines human carrying capacity?
• Will technological advances overcome
  environmental resistance that populations face?
• Should populations be controlled? If so, what is
  given up?

6
Core Case Study Are There Too Many of Us? (2)

• Growing populations cause increased environmental
  stress
• Infectious diseases
• Biodiversity losses
• Water shortages
• Traffic congestion
• Pollution of the seas
• Climate change

7
The trade off

• We have been increasing the Earths carrying
  capacity for humans at the expense of undermining
  the structure ecosystems and its ability to
  support for all life on Earth

8
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.

9
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

10
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?
• CCC optimum level to allow most people to live
  in reasonable comfort and freedom, sustainably

11
12
World population projections by UN
11
High10.8
10
Medium 9.3
9
8
7
Population (billions)
Low7.8
6
5
4
3
2
2050
2040
2030
2020
2010
2000
1990
1980
1970
1960
1950
Year
Fig. 6-2, p. 125
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Science Focus How Long Can the Human Population
Keep Growing?

• Thomas Malthus and population growth 1798
• Growth of supplies is linear
• Growth of population is exponential
• So far not true for industrial age
• Humans have altered 83 of the earths land
  surface

13
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
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 polluting and climate-changing
fossil fuels
Fig. 6-A, p. 124
14
Video Bonus for a baby
1.2 million added to developed world 80.8
million added in 3rd world Annual statistics
15
Exit questions for 6.1

• Q1) Which of the 3 major environmental worldviews
  summarized on pg 20 in text, do you believe
  underlie the two major positions on whether the
  world is over populated? Why?
• Q2) list 3 factors that account for rapid growth
  of the world human population over the past 200
  years.
• Q3) How many of us are likely to be here in 2050?
• Q4) What is cultural carrying capacity of a
  population? How is this concept considered in
  answering whether the earth is over-populated?

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 per 1000
• Crude death rate deaths per 1000

18
Global Connections The Worlds 10 Most Populous
Countries in 2008, 2025
19
China
1.3 billion
1.5 billion
1.1 billion
India
1.4 billion
304 million
USA
357 million
240 million
Indonesia
292 million
Pakistan
173 million
229 million
195 million
Brazil
229 million
148 million
Nigeria
205 million
147 million
Bangladesh
180 million
142 million
Russia
2008
129 million
2025
128 million
Japan
119 million
Fig. 6-3, p. 126
20
Women Having Fewer Babies but Not Few Enough to
Stabilize the Worlds Population

• Fertility rate types
• Replacement-level fertility rate
• How many kids a couple have to have to replace
  themselves (slightly more than 2)
• Total fertility rate (TFR)
• Average number of children born to women in a
  population during their reproductive years

21
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

22
TFR Rates for the U.S. between 1917 and 2008
23
4.0
3.5
3.0
2.5
2.1
2.0
Births per woman
Replacement level
Baby boom (194664)
1.5
1.0
0.5
0
1990
2010
2000
1920
1930
1940
1950
1960
1970
1980
Year
Fig. 6-4, p. 127
24
Crude Birth Rates in the U.S. from 1910 to 2008
25
32
30
28
26
24
22
Births per thousand population
20
18
End of World War II
16
Demographic transition
Depression
14
Echo baby boom
Baby boom
Baby bust
0
1910
1920
1930
1940
1950
2000
2010
1990
1960
1970
1980
Year
Fig. 6-5, p. 127
26
Some Major Changes That Took Place in the U.S.
between 1900 and 2000
27
Stepped Art
Fig. 6-6, p. 128
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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 pensions
• Urbanization (self-reliance or lack thereof)
• Educational and employment opportunities for
  women

29
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

30
Several Factors Affect Death Rates (1)

• Life expectancy
• the average number of years a new-born can expect
  to live
• Infant mortality rate
• The number of babies out of every 1000 born who
  die before their first birthday

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Why are people living longer and fewer infants
dying?

• Increased food supply and distribution
• Better nutrition
• Medical advances
• Improved sanitation

32
Why is the life expectancy of US citizens less
than 41 other countries ?

• 45 million Americans lack healthcare
• Adults in US have one of the world s highest
  obesity rates

33
Several Factors Affect Infant mortality

• 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

34
Migration Affects an Areas Population Size

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

35
Case Study The United States A Nation of
Immigrants

• Historical role of immigration in the U.S.
• Since 1820, US admitted twice as many immigrants
  as all other countries combined
• Legal immigration
• Illegal immigration
• Currently 40 of population growth accounted for
  by immigration

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Immigration for or against

• For reducing immigration
• Magnet for worlds poor
• Stabilize our pop sooner
• Reduce environmental impact
• Less crime
• Against reducing immigration?
• US, jobs, economy, retirement

37
Legal Immigration to the U.S. between 1820 and
2003
38
2,000
1,800
1,600
1907
1,400
1914 New laws restrict immigration
1,200
Number of legal immigrants (thousands)
1,000
800
Great Depression
600
400
200
0
2010
2000
1980
1960
1940
1920
1900
1880
1860
1840
1820
Year
Fig. 6-7, p. 129
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Questions on 6.2

1. Describe population growth in the US, and explain
   why it is high compared to those of most other
   developed countries and China.
2. Is US over populated? Explain.
3. Distinguish between life expectancy and infant
   mortality rate and explain how they affect the
   population size of a country.

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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
• Reproductive ages
• Postreproductive ages

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Male
Female
Male
Female
Male
Female
Male
Female
Expanding Rapidly Guatemala Nigeria Saudi Arabia
Expanding Slowly United States Australia China
Stable Japan Italy Greece
Declining Germany Bulgaria Russia
Prereproductive ages 014
Postreproductive ages 4585
Reproductive ages 1544
Fig. 6-8, p. 131
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Tracking the Baby-Boom Generation in the United
States
44
Population Structure by Age and Sex in Developing
and Developed Countries
45
Developed Countries
85
8085
7579
Male
Female
7074
6569
6064
5559
5054
4549
4044
Age
3539
3034
2529
2024
1519
1014
59
04
300
200
100
0
100
200
300
Population (millions)
Fig. 6-9a, p. 131
46
Developing Countries
85
8085
7579
Male
Female
7074
6569
6064
5559
5054
4549
4044
Age
3539
3034
2529
2024
1519
1014
59
04
300
200
100
0
100
200
300
Population (millions)
Fig. 6-9b, p. 131
47
We Can Use Age-Structure Information to Make
Population and Economic Projections

• Baby boomers
• Dominate demand for goods and services
• Determine who gets elected and what laws are
  passed
• Force succeeding generations to pay for them
• Job market when they retire
• Create a shortage of workers (immigration,
  automation, dilution of political power)

48
Populations Made Up of Mostly Older People Can
Decline Rapidly

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

49
Some Problems with Rapid Population Decline
Can threaten economic growth
Labor shortages
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 health-care costs
Pensions may be cut and retirement age increased
Fig. 6-11, p. 133
50
Populations Can also 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, in countries where
  39 affected--LE dropped to 34-40 years
• International community called upon to
• Reduce the spread of HIV through education and
  health care
• Financial assistance and volunteers (why or why
  not help?)

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Exit questions on 6.3

• Q17) Explain how the age structure of a
  population affects its growth (population and
  economic).
• Q18) what are some problems related to rapid
  population decline from an aging population?

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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.

53
As Countries Develop, Their Populations Tend to
Grow More Slowly

• Demographic transition stages
• Preindustrial
• Transitional
• May lead to a demographic trap
• Industrial
• Postindustrial

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Four Stages of the Demographic Transition
55
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 (responsibilty)
• Slow and stabilize population growth
• Invest in family planning
• Reduce poverty
• Elevate the social and economic status of women

57
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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Education

• Globally, 900 million girls are often kept home
  to work instead of being sent to school
• Teaching women to read has a major impact on
  fertility rates
• Women who can not read often have 5-7 kids,
  compared to 2 or less in societies where almost
  all women read.

59
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
• 300 million people moved from poverty to middle
  class
• Gender imbalance
• Fast-growing economy
• Fast aging population
• Face serious resource and environmental problems

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Environmental concerns in china

• Raw materials are scarce
• We dont have enough land
• Population is growing
• Half of our water in our seven largest rivers is
  useless
• One-third of the urban population is breathing
  polluted air

62
Case Study Slowing Population Growth in India

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