The Human Population

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Chapter 7 The Human Population
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Set up a graph like this to use with the data on
the following slide
or B.G. (before )
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(No Transcript)
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Global Population Growth
At the present rate, the global human population
increases by roughly a million lives every 5
days 1.8 million babies are born and 800,000
people die. 
Figure 7.1
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Global Population Growth
The 12 Most Populous Countries in the World
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Think and Write(We already did this as an
exercise in class)

1. What are some limiting factors to life on Earth?
   (How many people do you think it can
   support?)
2. How have humans extended average life spans?
   (longer lives lower infant mortalities)
3. How have humans increased the ability of our
   planet to support life? (to exceed limits of
   natural resources)
4. Why is population an environmental issue?
5. What are some ways of limiting population?
6. What are some controversies of limiting
   population?

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Earths Carrying Capacity

• In 1798, Thomas Malthus observed that the human
  population was growing exponentially, while the
  food supply we rely on was growing linearly. He
  predicted that eventually, human population size
  would exceed the food supply.

• Today, many scientists argue that the growing
  population of humans provides an increasing
  supply of intellect that leads to increasing
  amounts of innovation. 
• By using creativity, humans can alter Earths
  carrying capacity. This is one of the
  fundamental ways in which humans differ from most
  other species on Earth.

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Innovation ? Population

• Agricultural Revolution
• Around 8,000 years ago, humans transitioned from
  hunting and gathering to being able to grow
  their own food. This allowed communities to be
  more efficient with their time and efforts
  increasing their ability to feed a larger
  population.
• Industrial Revolution
• In the 1800s, the use of fossil fuels enabled
  manufacturing to increase production capacity
  that would affect all human needs food,
  medicine, housing, clothing, etc. Health and
  sanitation lowered death rates increasing
  population.

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Factors that Drive Human Population Growth

• The next several slides address demography -
  the study of human populations and population
  trends.
• In this order
• Changes in Population Size
• Fertility
• Life Expectancy
• Age Structure
• Migration

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Changes in Population Size

• Immigration- the movement of people into a
  country
• Emigration- the movement of people out of a
  country.
• Net migration rate- the difference between
  immigration and emigration in a give year per
  1,000 people in the country.

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Changes in Population Size

• Crude birth rate (CBR) the number of births per
  1,000 individuals per year.
• Crude death rate (CDR) the number of deaths per
  1,000 individuals per year.

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Changes in Population Size
Examples from p.182 in textbook

• Global population growth rate
• (CBR - CDR) / 10
• National population growth rate
• (CBR immigration) - (CDR emigration) / 10
• Doubling time rule of 70 70/growth rate

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Fertility

• Total fertility rate- an estimate of the average
  number of children that each woman in a
  population will bear.
• Replacement level fertility- the total fertility
  rate required to offset the average number of
  deaths in a population and for the current
  population size to remain stable.

• Developed countries- (countries with relatively
  high levels of industrialization and income) avg
  replacement-level fertility of 2.1
• Developing countries- (low levels of
  industrialization and income of less that 3 per
  day). Higher mortality among young people needs a
  TFR gt 2.1 for replacement-level fertility.

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Life Expectancy (end of life)

• Life expectancy- the average number of years that
  an infant born in a particular year in a
  particular country can be expected to live.
  (given the current average life span and death
  rate of that country)

Life expectancy is generally higher in countries
with better health care. A high life expectancy
also tends to be a predictor of high resource
consumption rates and environmental impacts.
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Life Expectancy (birth rate)

• Infant mortality rate- the number of deaths of
  children under 1 year of age per 1,000 live
  births.
• Child mortality rate- the number of deaths of
  children under age 5 per 1,000 live births.

 Countries with low life expectancy and high
infant mortality rate, it is likely that the
countrys population does not have sufficient
health care or sanitation and that potable
drinking water and food are in limited supply.
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Age Structure Diagrams

• Visual representations of male and female age
  structure within a country

1. Population pyramid An age structure diagram
   that is widest at the bottom and smallest at the
   top, typical of developing countries. Will
   continue to grow.
2. Equal numbers in young and older age groups
   represent no growth.
3. Inverted pyramid more older than younger people,
   population will shrink.
4. China is in transition.

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The Demographic Transition(use the blank graph
Mr. Sierra provided to copy the curves below)

• Theory of the demographic transition as a
  country moves from a subsistence (survival)
  economy to industrialization and increased
  affluence, it undergoes a predictable shift in
  population growth.

Phase 3 Stable population growth as the economy
and educational system improves and people have
fewer children.
Phase 4 Declining population growth because the
relatively high level of affluence and economic
develop encourage women to delay having children.
Phase 2 Rapid population growth because birth
rates remain high but death rates decline due to
better sanitation, clean drinking water,
increased access to food and goods, and access to
health care.
Phase 1 Slow population growth because high birth
rates and high death rates offset each other.
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Family Planning

• Family planning- the regulation of the number or
  spacing of offspring through the use of birth
  control.

As the education levels of women increase and
they earn incomes of their own, people tend to
have fewer children. Many delay having children
because of the demands of school and work,
resulting in fewer reproductive years. In
addition, women with more education and income
tend to have more access to information about
methods of birth control, they are more likely to
interact with their partners as equals, and they
may choose to practice family planning with or
without the consent of their partners.
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? Environmental Impacts ?

• Population is a critical factor in the impact of
  humans on Earth. 
• Resources consumption energy, water, minerals,
  etc. for
• Farming/Agriculture
• Construction
• Manufacturing
• Transportation
• Generating waste
• Deforestation
• Habitat Loss
• Pollution

Affluence - having a lot of wealth such as money,
goods, or property.
Ecological Footprints
Only 1/5 of the human population lives in
developed countries, but they (we) consume more
than 1/2 of the worlds energy and resources,
2-10 times the environmental impact of people in
a developing country!
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The IPAT Equation

• To estimate the impact of human lifestyles on
  Earth we can use the IPAT equation
• Impact Population x Affluence x Technology
• (see page 192 for descriptions of these factors)

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Economics
The relationship between economic development
and population growth rate for developing
nations.
The Impact of Affluence

• Gross domestic product (GDP)- the value of all
  products and services produced in a year in that
  country.
• A countrys GDP often correlates with its
  pollution levels.

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URBAN growth

• Urban populations represent one-half of the human
  population, but consume three-fourths of Earths
  resources. 

• More than 75 of people in developed countries
  live in urban areas.
• In developing countries,
• 44 of people live in urban areas, but that
  number is increasing more rapidly than in
  developed countries and will probably reach 56
  by 2030.

• Table 7.1 shows that, of the 20 largest cities in
  the world, 16 are in developing countries. 
  Worldwide, 
• almost 5 billion people are expected to live in
  urban areas by 2030.