1. Human Population Growth
Chapter 5
Human Population Growth

2. Human Population Growth— What's the Problem?
7 billion humans on Earth
As of autumn 2011
Rapid population growth
Some say it's the source of all problems
Increase impact
Rate of consumption
Rates regionally and economically based
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3. 5.1 The History of Human Population Growth
Periods of growth
Pre-agricultural period
100,000 years
Culture
Tens of thousands of years to double
Population 5–10 million at end
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4. 5.1 The History of Human Population Growth
Periods of growth
Agricultural period
Began 10,000 years ago
Domestication of plants and animals
Doubling time 1,000 years
500+ million years at end of period
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5. 5.1 The History of Human Population Growth
Periods of growth
Industrial period
Technology advance
Fossil fuels
Sanitation, medicine
Death rates decline
Our current period
Population 7 billion
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6. 5.1 The History of Human Population Growth
Demographic transition model
As a society advances, human population growth goes through stages
Stage 1
Before economic development
Death rate high
Birth rate high
Thompson's findings have subsequently been verified and translated into the demographic transition model.
Stage 1. The first stage of the demographic transition model is the period prior to economic development. During this stage, human populations are limited by a low availability of food and a high prevalence of disease—factors that negatively affect human well-being. Consequently, death rates are high, particularly among the young. Families compensate for high death rates by having many children, a behavior that is reflected in high birth rates.
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7. 5.1 The History of Human Population Growth
Demographic transition model
As a society advances, human population growth goes through stages
Stage 2
Mortality transition
Death rate decreases
Birth rate stays high
Rapid population growth
The second stage of the demographic transition is called the mortality transition. In this stage, improved economic conditions relieve food shortages, produce better living conditions and health care, and expand access to education. The death rate decreases while the birth rate stays high or even increases. As a result, there is rapid, sustained population growth.
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8. 5.1 The History of Human Population Growth
Demographic transition model
As a society advances, human population growth goes through stages
Stage 3
Fertility transition
Death rate stays low
Birth rate decreases
Population growth slows
Stage 3. In the third stage of the demographic transition, the fertility transition, continued economic development produces social and cultural changes that lead to lower birth rates. People may delay starting families, which lowers total fertility rates. Families may limit their number of children by using contraceptives or other means of family planning. In the fertility transition, the death rate remains low and the birth rate decreases, so population growth slows.
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9. 5.1 The History of Human Population Growth
Demographic transition model
As a society advances, human population growth goes through stages
Stage 4
Stability transition
Low birth and death rate
Birth and death rates equal
Zero population growth or negative growth
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10. 5.1 The History of Human Population Growth
Latin American growth as a case study on demographic transition
46 separate and diverse countries
Stage 1
1600–1900
Stage 2
1900–1969
Stage 3
1970
Stage 4
Projected 2050
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11. 5.2 Global Variation in Human Population Growth
Birth rates
Influenced by various factors
Wealth
More wealth, lower birth rates
Age
Age-specific birth rates
Children/1000 years within age classes
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12. 5.2 Global Variation in Human Population Growth
Death rates
Influenced by various factors
Wealth
Increased nutrition, health care, sanitation
Infant mortality rate
Percentage of infants that die before age one
Reduces with wealth
Poor countries' rate 18 times higher
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13. 5.2 Global Variation in Human Population Growth
Death rates
Survivorship
Number of years members of a specific group lives (example: 60% survive to age 25)
Wealth, sex affects
Life expectancy
Same factors affect
United States: boys 77.7 years, girls 82.1
Globally 45.6–68.9 years in last five decades
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14. 5.2 Global Variation in Human Population Growth
Age structure
Determined by survivorship and age-specific birth rate
Age-structure pyramid
Graphically display age structure
Shape indicates rate of population growth
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15. ETHIOPIA 2010 UNITED STATES 2010 Median age 38 years Median age
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16. 16 CANADA 2010 CANADA 2050 NIGER 2010 NIGER 2050 Median age 37 years
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17. 5.2 Global Variation in Human Population Growth
Migration
Relocation of humans
Immigration
Moving in
Pull factors–freedom, education, employment
Emigration
Moving out
Push factors–war, famine, oppression, persecution
Net migration rate
Difference between immigration and emigration
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18. 5.3 Predicting Human Population Growth
Thomas Malthus
Lived in 1700s
Observed population growth in American colonies
Noted human exponential growth
Predicted problem from growth
Diminished well-being, poverty
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19. 5.3 Predicting Human Population Growth
Population forecasts
Past estimates of 1930 and 1960 flawed
Assumed current economics would continue
United Nations data
9 billion by 2050
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20. 5.4 Resource Use and Population Sustainability
Sustainability vs. carrying capacity
Carrying capacity
Size of population environment can support
As population approaches carrying capacities, death rates increase and birth rates decrease
Sustainability of humans must be below carrying capacity
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21. 5.4 Resource Use and Population Sustainability
Human resource use
Ecological footprint
Area of land needed to supply resources consumed
Size of footprint varies greatly between countries
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22. 5.4 Resource Use and Population Sustainability
Human resource use
Biocapacity
Area and quality of land to supply resources
Population exceeds biocapacity when ecosystem's goods must be imported
Estimated that world's countries running beyond global biocapacity
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23. 5.4 Resource Use and Population Sustainability
Affluence and technology
Impacts environment globally
IPAT equation (I = P x A x T)
Determines human impact
I = impact (environmental)
P = population (size, growth, distribution)
A = affluence (individual consumption)
T = technology (energy using items)
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24. 5.5 Managing Population Growth
Family planning
Efforts to manage birth rate
Education decreases birth rate
Some countries growing too fast
Resource pressures
China, India
Others too slow
Reduced workforce, economic issues
Japan, Spain, Italy, and others
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25. 5.5 Managing Population Growth
Three examples of managing population growth
China
One child policy
Mexico
Communication, education, counseling, contraceptives
India
Similar to Mexico, not as successful
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