The Human Population as an Environmental Problem

1
Chapter 5

• The Human Population as an Environmental Problem

2
A Few Current NumbersSourcepopulation reference
bureau

• World Population - 6.48 billion
• Percent growth 1.2
• US Population - 297 million
• Percent growth 0.6

3
Most Populous CountriesSourcepopulation
reference bureau

• 1 China - 1.3 billion
• Percent growth 0.6
• 2 India - 1.1 billion
• Percent growth 1.7
• 3 USA - 297 million
• Percent growth 0.6

4
Most Populous CountriesSourcepopulation
reference bureau

• 4 Indonesia - 222 million
• Percent growth 1.6
• 5 Brazil - 184 million
• Percent growth 1.3
• 6 Pakistan - 162 million
• Percent growth 2.4

5
A Few Current TrendsSourcepopulation reference
bureau

• More developed countries - 1.2 billion
• Percent growth 0.1
• Less developed countries - 5.3 billion
• Percent growth 1.5 (1.8 w/out china)

6
Effect of technology (1)

• Impact of humans depends on two factors the
  number of humans, and the impact of each
• Human impact varies w/lifestyle, this is
  sometimes called ecological footprint

7
Effect of technology (2)

• Technology allows us to overcome (temporarily)
  Malthus prophecy
• Buttechnology increases our impact and adds
  additional types of impact

8
Malthus Prophecy

• Food is necessary for people to survive
• People will continue to reproduce
• Population growth will outpower agricultural
  growth

9
Considering Numbers

• World Population 6.4 billion
• Area of Texas 261,797 sqft
• Put every person on earth in Texas and they each
  get 1140 sqft or 38 people per acre
• BUT.

10
More on Ecological Footprint

• In USA each person requires 10.4 hectares for
  resources
• In Bangladesh each person requires 0.5 hectares
  for resources
• World 2.8 hectares (only 2.1 available)
• SourceIPCC

11
Ecological Footprint bottom line

• Less populous nations may have greater
  environmental impact than more populous
  countries.
• See pg 78

12
5.1 Key Points

• Earth is at 6.5 and growing at 1.2
• Developing countries have both higher numbers and
  higher growth rates than developed countries
• Human impact is a product of the number of humans
  and the impact of each

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5.1 Key Points (cont)

• Technology increases number of humans and can
  change type of impact
• Malthus made key points about carrying capacity
  and MUST ultimately be right

14
Key Population concepts

• Age structure
• Demographic Transition
• Fertility
• Human population v. environment
• Deathrate increase
• Standard of living and pop factors

15
History of Human Pop.

• I - Hunter Gatherer, a few mil.
• II - Rise of agriculture, allowed density
  increase
• III - Industrial revolution, rapid increase
• IV - Present, slow in ind, but fast in devel.

16
Population factors

• g b - d (growth births - deaths)
• Crude rates per 1000
• Percent rate per 100
• So, 9 births per 1000 crude rate 0.9 birth
  rate

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Important terms

• Maximum lifetime - genetically determined
  potential
• Life expectancy - average expected lifespan at
  birth

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5.2 Key points

• As technology changed human lifestyle, patterns
  of pop growth changed
• g b - d
• Key terms ie crude growth rate, max lifetime,
  etc

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A note on book numbers

• Trends IDed on p. 83 - 84
• But, according to pop data sheet no countries are
  growing at 5, a few are at 3.5 (highest listed)

20
Logistic Growth Curve
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Why Logistic is limited

• Three assumptions
• Constant environment
• Constant carrying capacity
• Homogeneous population
• Especially unreliable if technology changes death
  rates

22
Predicting Human Population

• Using logistic growth for this requires an
  inflection point
• BUThumans have not reached a clear inflection
  point
• 3 UN projections are on page 85

23
The Demographic Transition