1. Human Population
Chapter 6

2. Chapter Overview China: One Child Policy Case Study
Our World at 7 Billion
Demography
Population and Society
Family Planning and Reproductive Policy

3. Central Case Study: China’s One-Child Policy
In 1970, China’s 790 million people faced starvation
The government instituted a one-child policy
The growth rate plummeted
The policy is now less strict but has unwanted consequences:
Killing of female infants
Black-market trade in teenaged girls

4. Our world at 7 billion and counting…

5. Our world at seven billion
Populations continue to rise in most countries
Particularly in poverty-stricken developing nations
Although the rate of growth is slowing, we are still increasing in numbers
Counting to 1 billion (1/second) would take 31 years—it would take 221 years to count to 7 billion!

6. Just how fast is the population growing?
Our population grows by over 80 million each year
It took until 1800 to reach 1 billion
We added 6 more billion in 130 years
We added the most recent billion in 12 years
Because of exponential growth (increase by a fixed %), even if the growth rate remains steady, population will continue to grow

7. Growth rates vary from region to region
Use natural log to calculate the time needed for growth
Ln of 2 is
Website to explain is betterexplained.com
At today’s 1.2% global growth rate, the population will double in 58 years (natural log(ln) of doubling or 2…70/1.2 = 58)
If China’s rate had continued at 2.8%, it would have had 2 billion people within 25 years

8. Is there a limit to population growth
Is there a limit to population growth?(Have we reached our carry capacity?
Technology, sanitation, medication, and food increase population
Death rates drop, but not birth rates
Earth’s carrying capacity for people?
2 billion prosperous people
33 billion very poor people
Thomas Malthus’ An Essay on the Principles of Population (1798)
War, disease, starvation will reduce populations

9. Different views on population growth
Thomas Malthus’ An Essay on the Principles of Population (1798)
War, disease, starvation will reduce populations
Paul Ehrlich’s The Population Bomb (1968) predicted that population growth would lead to famine and conflict
But intensified food production fed more people(Green Revolution)
Many economists think depleted resources will be replaced or new resources created
But many resources (e.g., species) cannot be replaced
Quality of life will suffer with unchecked growth
Less space, food, wealth per person
Population growth is a problem if it depletes resources, stresses social systems, and degrades the environment

10. Population growth: causes and consequences

11. Ehrlich and Holden’s IPAT model
Using the IPAT model: I = P  A  T
Our total impact (I) on the environment results from:
Population (P): individuals need space and resources
Affluence (A): per capita resource use
Technology (T): increases use of, or protects, resources
Sensitivity (S): a fourth factor showing how sensitive an area is to human pressure
Further model refinements include the effects of education, laws, and ethics on the formula
Model was discovered by Paul Ehrlich and John Holden 1974)

12. Do Now: in notes Brainstorm with a classmate +/- of technology
Make 3 columns-
Technology

13. China is an example of the IPAT formula
Elements of the IPAT equation can combine
Causing tremendous impact in a very short time
Modern China’s rapid development is causing unprecedented environmental challenges
Intensive agriculture is eroding farmland
Overuse has dried up the mighty Yellow River
Increasing vehicles are causing urban pollution and massive traffic jams
China shows us what the rest of the world can become

14. Demography

15. Do Now Recall population ecology…
What aspects of the population of a species are studied or examined?
What do you know…
People live (inland cold interior, coastal tropical)?
The most people live in(India, China or USA)?
Populations are getting (younger, older)?

16. Demography
Demography: applying the principles of population ecology to the study of change in human populations
Demographers study:
Population size
Density and distribution
Age structure
Sex ratio
Birth, death, immigration, and emigration rates

17. Population size and density
The UN predicts 9 billion humans by 2050
Highest density: temperate, subtropical, tropical biomes
Coasts, rivers, cities
Lowest density: extreme climates (desert, rainforest, tundra)
Also, areas away from water
If women have just 0.5 child fewer than the medium scenario, there will be 8, not 9.15, billion by 2050

18. Population distribution: What can you conclude?
Humans are unevenly distributed around the globe
Many unpopulated areas (e.g., deserts, arid grasslands) are environmentally sensitive
High S value in the modified IPAT equation
Vulnerable to humans (agriculture, ranching, etc.)

19. How does age structure affect population structure?
Age structure: describes relative numbers of individuals in each age class
Shown by age structure diagrams (population pyramids)
Wide base: has many young that haven’t reproduced yet
Population will soon grow rapidly
Even age distribution:
Remains stable
Births = deaths

20. Examples: Canada’s age structure is balanced (growth rate = 0.4%)
Madagascar’s age structure is heavily weighted toward the young (growth rate = 2.9%)

21. Trend Now: Population is getting older
The global mean age is now 28—in 2050, it will be 38
China’s age structure is changing
In 1970, the median age was 20
By 2050, it will be 45
Although fewer people will be working to support social programs, the elderly can remain productive

22. Sex ratios affect population dynamics
Human sex ratios at birth slightly favor males
For every 100 females born, 106 males are born
Chinese females are selectively aborted
120 boys were reported for 100 girls
The undesirable social consequences?
Many single Chinese men
Teenaged girls are kidnapped and sold as brides

23. What factors determine how a population changes?
Rates of birth, death, and migration determine whether a population grows, shrinks, or remains stable
Birth and immigration add individuals
Death and emigration remove individuals
Technological advances cause decreased deaths
The increased gap between birth and death rates resulted in population expansion
Natural rate of population change: change due to birth and death rates alone, excluding migration

24. Falling growth rates do not mean fewer people
Despite falling growth rates, the population continues growing by adding 80 million people each year

25. Factors affecting total fertility rate
Total fertility rate (TFR): the average number of children born to each female during her lifetime
Replacement fertility: the TFR that keeps the size of a population stable (about 2.1)
Causes of decreasing TFR:
Medical care reduces infant mortality
Urbanization increases childcare costs
Children go to school instead of working
Social Security supports the elderly
Educated women enter the labor force

26. Life expectancy is increasing
People live longer in countries with good sanitation, health care, and food
Urbanization, industrialization, and personal wealth reduces rates of infant mortality
Which increases life expectancy (the time a person can expect to live)
Demographic transition: a model of economic and cultural change
Explains the declining death and birth rates in industrializing nations

27. The demographic transition
As they industrialize, nations move from a stable pre-industrial state of high birth and death rates
To a stable post-industrial state of low birth and death rates
Industrialization decreases mortality rates
So there is less need for large families
Parents invest in quality of life, not quantity of kids
Death rates fall before birth rates
Resulting in temporary population growth

28. The 4 stages of the demographic transition
Pre-industrial stage: low population growth
High death (disease, starvation, few medicines) and birth (compensation for mortality) rates
Transitional stage: industrialization, increased food and medical care reduce mortality rates
High birth rates cause population to surge
Industrial stage: women get jobs and use birth control
Kids do not need to help get food
Post-industrial stage: low birth and death rates stabilize populations

29. The demographic transition’s four stages
Population growth is seen as a temporary phenomenon

30. Is the demographic transition universal?
It has occurred in Europe, the U.S., Canada, Japan, and other nations over the past 200–300 years
But it may or may not apply to developing nations
The transition could fail:
If the population is too large to allow the transition
In cultures that place greater value on childbirth or grant women fewer freedoms
For people to attain the material standard of living of North Americans, we would need the natural resources of 4.5 more Earths

31. Population and society

32. Do Now: On Socrative
Should we fund efforts for family planning in other countries or not?

33. Population and Society: family planing is key to slowing growth rate
Family planning: efforts to plan the number and spacing of children
The greatest single factor slowing population growth
Clinics offer advice, information, and contraceptives
Birth control: controlling the number of children born by reducing the frequency of pregnancy
Contraception: deliberate prevention of pregnancy through a variety of methods
Drawback -Hindered by religious and cultural influences
Benefits- it works! Rates range from 10% (Africa) to 86% (China)

34. Empowering women reduces fertility rates
A nation’s fertility rates drop when women gain access
To contraceptives, family planning programs, and educational opportunities
Women need control over their reproductive window:
The time in their lives when they can become pregnant
Educating women reduces fertility rates, delays childbirth, and gives them a voice in reproductive decisions

35. A woman controls her reproductive window
Jobs or school delays the birth of a first child
Contraceptives space births
The window is “closed” after the desired number of kids

36. Policies and family planning work
Funding and policies that encourage family planning lower population growth rates in all nations
Thailand’s education-based approach to family planning reduced its growth rate from 2.3% to 0.6%
Brazil, Mexico, Iran, Cuba, and other developing countries have active programs
1994’s UN population conference in Cairo, Egypt, called for universal access to reproductive health care
Offer education, health care, and address social needs
Global funding has fallen 33%, slowing progress

37. Family planning reduces fertility rates
Blue: with family planning
Red: without family planning

38. Poverty and population growth are correlated
Poor societies have higher population growth rates
Poverty and population growth make each other worse
99% of the next billion people added will be born in poor, less developed regions that are least able to support them

39. Poverty causes environmental degradation
Population growth in poor nations increases environmental degradation
Farming degrades soil in arid areas (Africa, China)
Poor people cut forests, deplete biodiversity, and hunt endangered species
Poor people hunt “bush meat”—driving even great apes to extinction

40. Wealth also impacts the environment
Affluent societies have enormous resource consumption
With severe, far-reaching environmental impacts
Ecological footprints are huge
One American has as much environmental impact as 3.5 Chinese or 9 Indians or 13 Afghans

41. We must reduce population growth and consumption
For a high standard of living and quality of life for all, developing nations must slow their population growth
Their consumption is also increasing
Developed nations must slow their consumption
Our global ecological footprint is 50% more than the Earth can support

42. Conclusion The human population is larger than it has ever been
Rates are decreasing but populations are still rising
Most developed nations have passed through the demographic transition
Expanding women’s rights slows population growth
How will the population stop rising?
The demographic transition, governmental intervention, or disease and social conflict?
Sustainability requires a stabilized population to avoid destroying natural systems