Chapter 4 - Human Population as an Environmental Problem

Case Study: Bangladesh

Basic Concepts

• Population and Technology: 2 main dangers 1. Numbers of people

2. Impact of each person on the environment

• I = PAT

• Your text: pg 64: T = P x I

Relative Impact Avg. American vs. Others

Developing countries represent a larger and larger share of world population because of higher populations and higher birth rates.

BIG PLAYERS IN THE FUTURE!

• USA• CHINA• INDIA• INDONESIA• BRAZIL• RUSSIA• MEXICO

All meet the following:

2. Big Area

3. Big Economy

4. Lots of People!

For most of human history, population grew slowly, but in modern times it has suddenly "exploded."

agriculture

Industrial rev.

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Fig 5.4 United States population 1790 to 2000.

Tapering off?

1 million people added to the world every 4 days!!

Number of Women 15 to 49Billions

0.62

0.86

1.32

1.76

1.982.06

1950 1970 1990 2010 2030 2050

Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.

Women of Childbearing Age

Projecting Population Growth• Doubling time = assume exp. growth

Estimate by: 70/annual growth rate %Called the Rule of 70!Very sensitive to growth rate

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Doubling time changes rapidly with the population growth rate.

Takes less time to double if high growth rate

Population Doubling Time Examples:

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Logistic growth curve.

• Predicting HPG:• The point at which logistic the pop growth

curve begins to slow toward carrying capacity is called the inflection point.

We are probably not there yet.

The Demographic Transition• Multi-stage pattern of change• Leads to decline in growth rates

1. Lifestyle Improvement:

2. Pop. still grows:

3. Birth rate drops:

Fig. 6.15 This figure shows population profiles for developed and developing countries, projected to the year 2025.

Improved living conditions

education

• Acute or epidemic disease:More of a problem in developing

countriesExamples:

• Chronic disease More of a problem in developed

countriesExamples:

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Fig 5.9 Causes of mortality in industrializing, developing and industrialized nations.

• Carrying capacity

• If exceeded, environment will be changed to the point of lowering the pop.

• Difficult to calculate globally because standards of living are not all the same

• Per capita availability =

• We are nearing the limit of productive capacity with today’s technology

• Age structure:• It’s the proportion of the pop. that is in each

age class

TFR = total fertility rate:

Replacement level fertility

The number of women in their childbearing years has increased since the 1950s and is projected to continue to increase to 2050. The number of children per woman has declined since the 1950s and is projected to continue to decline. Even though women have on average fewer children than their mothers, the absolute number of babies being born continues to increase because of the increases in the total number of women of childbearing age.

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Constant TFR

Slow fertility reduction

Rapid fertility reduction

Total fertility rate decreases as income increases.

© 2003 John Wiley and Sons Publishers

How to Slow Population Growth

• Simplest and most effective ways:• Delay marriage

• Delay the onset of having children• Educate and raise status of women

• Birth Control in Developing Countries• 1. Breast feeding:• 2. Family planning • 3. Abortion:

• National Programs:• Most countries have some official

population policy. Effectiveness varies.