2. Why Should You Care About
Population Growth
• Human population 7 billion
• Every year 83 million additional
• 9.3 billion by 2050
• Population growth central to environmental
problems and solutions
• Consumption per-capita (Figure 2.1a,b)
• Ecological footprint of U.S. much greater than
India or world average
• Total number of people
• Study of population = demographics
4. What Do You Need to
Know?
Population Growth and Limits to Growth
-Population dynamics
-Exponential growth (Figure 2.2)
-Fixed percentage per unit of time
7. History of Human Population
Growth
Historical J-curve of exponential growth
Human population expanded because of:
- Energy use from coal, oil, and other fuels
- Modern agriculture
- Use of machines and other technologies.
Humans now live in almost all of earth’s climate
zones.
9. Recent Changes in Growth
Rates
- Rate of exponential declining (Figure 2.7)
- Number of babies per woman decreases
10. Distribution of Birth Rates
Birth rates not distributed evenly in world
- 1/80 infants in developed world, 79/80 in less-
developed countries
- Population in less developed world will increase
faster than developed in future
11. Dynamics of Human Population
Growth
Population change = (Births + Immigration) − (Deaths + Emigration)
total fertility rate (TFR)
>2.0, population growths
<2.0 population decreases
TFR not even throughout world
economic factors
social factors
12. Population Growth in the
United States
1900-2012 US population increased from 76 to 315 million
- High birth rates + immigration
- Fertility rates in US lowered, but still increases population
- 1/3 of US increase 2012-2050 due to immigration
Age structure important
- Prereproductive
- Reproductive
- Postreproductive
- US expanding slowly
14. What Are the Problems?
Growing Ecological Footprints
- Nonrenewable can be depleted
- Renewable resources can be degraded or destroyed
- Soil is key slowly-renewable resource that needs to be
maintained
15. The IPAT Model
Impacts of different countries on environment
Three major factors considered:
- Population size (P),
- Affluence (A) or resource consumption per person
- Effects of technologies (T) (destructive or beneficial)
Impact (I) = Population (P) x Affluence (A) x Technology (T)
17. IPAT Results Vary
- Application of technology to IPAT model
can affect environment two ways
- Detrimental through additional
resource use or pollution
- Beneficial through avoiding depletion
of resources and reducing pollution
21. Empowering Women
Economic impact of women often undervalued
- 2/3 of all the hours of work performed every day
- Receive only a tenth of the world’s income
- Own less than 2% of its land.
Potential impact of empowering women on
environment
- Illiterate poor women typically have 5 to 7 children
- Literate poor women have average of 1 or 2 children
- Higher social and economic status reduce birth rates
23. Reducing Poverty
- Reducing poverty can have impacts on environment
- In general reduces birth rate
- Reduces the need to exploit resources
- Should consider increased resource consumption
- Promoting Family Planning
- Key role in lowering birth rates
- Problems continue
- About 42% of all pregnancies in less-developed
countries unplanned
in less-developed countries often not available
25. Example of India’s Programs
India’s Moderate Success in Reducing Population Growth
- First national family planning program (1952)
- Not very successful
- 1952-2012 400 million to 1.2 billion
- Annual growth increase from 5 to 18 million
- Reasons for lack of success varied
- Poor planning
- Bureaucratic inefficiency
- Low status of women
27. China’s One-Child Policy
Rapidly growing population in 1960’s
- Treat of starvation
- Family planning program started
Promotes one-child families
- Government provides
- Contraceptives
- Sterilizations
- Abortions
- For one-child families
- More food
- Free health care
- Salary bonuses
- Preferential jobs for child
Impact dramatic
- 1972-2012
- Total fertility drop 5.7 to 1.5
- Growing middle class
- Still very high population and problems
29. A Look to the Future
Environmental Refugees
Population growth and environmental degradation
can strip resources
- Environmental refugees
- Lack of food
- Sea level rise
- Displacement by war, often over resources
31. What Would You Do?
how can we personally deal with problems caused by population growth
- reduce number of children born
- have fewer children
- adopt rather than have children
- combination
- support slowing population growth.
- direct support by donations to agencies
- encouragement
Reducing personal ecological footprints.
- calculate personal footprint and adjust lifestyle
- driving energy-efficient vehicles and reduce driving
- reduce meat consumption
- insulate home
- energy-efficient appliances
- adjust buying habits
- buy less
- buy items that use less resources
32. What Would You Do?
How can we personally deal with problems caused by population growth?
33. Key terms for Chapter 2 review
• age structure
• carrying capacity
• demographic transition
• ecological tipping point
• environmental refugees
• exponential growth
• family planning
• infant mortality rate
• IPAT model
• less-developed country
• life expectancy
• limiting factors
• migration
• more-developed country
• overconsumption impacts
• overpopulation impacts
• poverty
• total fertility rate (TFR)
Hinweis der Redaktion
Figure 2.1 Compare these photos: (a) an American family of four from Pearland, Texas, with their major possessions, and (b)a family of five from the village of Shingkhey, Bhutan with all their possessions.
Figure 2.2 Plotting exponential world population growth on a graph (left) shows that it started out slowly but accelerated rapidly. The graph on the right (with a projection to 2050) shows how the U.S. population has also grown exponentially.
Figure 2.5 The human population has grown exponentially as represented by a J-shaped curve. In 2011, United Nations population experts projected that the population will reach about 9.3 billion by 2050 and may level off at about 10 billion by 2100 with the J-shaped curve changing to an S-shaped curve. (Data from the World Bank and United Nations, 2011; this figure is not to scale)
Figure 2.11 Typical population age-structure diagrams for countries with rapid (1.5–3%), slow (0.3–1.4%), zero (0–0.2%), and negative (declining) population growth rates. (Data from Population Reference Bureau)
Figure 2.16 This simplified representation of the IPAT model compares the environmental impacts of populations in less-developed and more-developed countries. Red arrows of different lengths show varying harmful effects of all three factors; green arrows of different lengths show varying beneficial effects of technology. The arrows are not intended to show precise measurements.
Figure 2.17 This coal-burning industrial plant in India (a) adds large quantities of carbon dioxide, soot, and other pollutants to the atmosphere. By contrast, the use of solar cells and wind turbines to produce electricity (b) has a very low harmful impact.
Figure 2.18 The demographic transition, experienced by many countries that have become industrialized, can take place in four stages.
Figure 2.20 These young girls from a rural village near the Kalahari Desert in the African country of Botswana typically spend two hours a day, two or three times a week, searching for and carrying firewood.
Figure 2.21 Every day, this child searches through an open dump in Manila, the Philippines, to collect items to sell. He and his family live in or near the dump.
Figure 2.23 This is home for this impoverished family in Bihar, India.
Figure 2.25 This mural in Guangzhou, China, promotes the government’s one-child policy.
Figure 2.27 Refugees from the Democratic Republic of Congo, Africa, arriving at a refugee camp in 2008.
a summary table or figure that shows personal strategies for reducing ecological footprints would be a good addition here