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Environment: The Science behind the Stories

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1 Environment: The Science behind the Stories
Lecture Outlines Chapter 8 Environment: The Science behind the Stories 4th Edition Withgott/Brennan

2 This lecture will help you understand:
Human population growth Different viewpoints on this growth Population, affluence, and technology’s effects Demography Demographic transition Factors affecting population growth The HIV/AIDS epidemic Population and sustainable development

3 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 The successful program has unintended consequences: Killing of female infants Black-market trade in teenage girls

4 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 It would take 30 years, counting once each second, to count to a billion! It would take 210 years to count to 7 billion!

5 The human population is growing rapidly
Our population grows by over 80 million each year It took until 1800 to reach 1 billion In 1930 (130 years later) we reached 2 billion We added the most recent billion in 12 years Due to exponential growth, even if the growth rate remains steady, population will continue to grow

6 Rates of growth vary from region to region
At today’s 1.2% global growth rate, the population will double in 58 years (70/1.2 = 58) If China’s rate had continued at 2.8%, it would have had 2 billion people in 2004

7 Is population growth a problem?
Technology, sanitation, medication, and increased food increase population Death rates drop, but not birth rates Population growth was seen as good Support for elderly, a larger labor pool Thomas Malthus’ An Essay on the Principles of Population (1798) Humans will outstrip food supplies War, disease, starvation reduce populations

8 Paul Ehrlich’s Population Bomb (1968)
Neo-Malthusians: population growth will increase faster than food production Population growth causes famine and conflict Civilization would end by the end of the 20th century Intensified food production fed more people

9 Population growth will affect quality of life
Population growth has caused famine, disease, conflict Prosperity, education, gender equality reduce birth rates Cornucopians (e.g., economists) say new resources will replace depleted ones But some resources (e.g., species) are irreplaceable Quality of life will suffer with unchecked growth Less space, food, wealth per person

10 Some governments fear falling populations
Policymakers believe population growth increases economic, political, and military strength But growth is correlated with poverty, not wealth Strong, rich nations have low growth rates Weak, poor nations have high growth rates Some nations offer incentives for more children Elderly need social services 49% of non-European nations feel their birth rates are too high

11 Population growth affects the environment
The IPAT model: I = P × A × T × S Total impact (I) on the environment results from: Population (P) = individuals need space and resources Affluence (A) = greater per capita resource use Technology (T) = increased exploitation of resources Sensitivity (S) = how sensitive an area is to human pressure Further model refinements include the effects of education, laws, and ethics on the formula

12 Population growth with limited resources
Impact equates to pollution or resource consumption Humans use 25% of Earth’s net primary production Technology has increased efficiency and reduced our strain on resources Resulting in further population growth For example: increased agricultural production Modern China’s increasing affluence is causing: Increased resource consumption Farmland erosion, depleted aquifers, urban pollution China shows us what the rest of the world can become

13 Population growth: causes and consequences

14 Human population growth and regulation

15 Human population growth and regulation

16 Demography Demography: the application of population ecology to the study of change in human populations All population principles apply to humans Environmental factors limit population growth Humans raise the environment’s carrying capacity through technology How many humans can the world sustain? 1–33 billion: prosperity to abject poverty Population growth can’t continue forever

17 Demography Demographers study: Population size
Density and distribution Age structure Sex ratio Birth, death, immigration, and emigration rates

18 Population size and density
The UN predicts 9 billion by 2050 Increased density impacts the environment But relieves pressure in less-populated areas Highest density: temperate, subtropical, tropical biomes Cities Lowest density: away from water

19 Population distribution
Humans are unevenly distributed around the globe Unpopulated areas tend to be environmentally sensitive (high S value in the IPAT equation) Vulnerable to humans (e.g., deserts, arid grasslands)

20 Age structure affects population size
Age structure diagrams (population pyramids) show age structure Wide base = many young: High reproduction Rapid population growth Even age distribution: Remains stable Births = deaths

21 Age structures: Canada vs. Madagascar
Canada’s age structure is balanced Madagascar’s age structure is heavily weighted toward the young

22 Changing age structures pose challenges
China’s age structure is changing In 1970, the median age was 20 By 2050, it will be 45 By 2050, over 300 million will be over 65 Fewer people will be working to support social programs

23 Many populations are aging
Many populations are getting older They will need care and financial assistance Taxes will increase for Social Security and Medicare But fewer dependent children means lower crime rates The elderly can remain productive

24 Sex ratios 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 Cultural gender preferences The government’s one-child policy The undesirable social consequences? Many single Chinese men Teenage girls are kidnapped and sold as brides

25 Factors in population change
Whether a population grows, shrinks, or remains stable depends on rates of birth, death, and migration Birth and immigration add individuals Death and emigration remove individuals Technological advances caused decreased deaths The increased gap between birth and death rates resulted in population expansion Natural rate of population change = due to birth and death rates alone

26 Immigration and emigration
War, civil strife, and environmental degradation cause people to flee their homes Each year, 25 million refugees escape poor environmental conditions This movement causes environmental problems No incentives to conserve resources

27 Falling growth rates do not mean fewer people
Slower rates of growth do not mean a decreasing population—population size continues to increase

28 Factors affecting total fertility rate
Total fertility rate (TFR) = the average number of children born to each female 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

29 Life expectancy is increasing
In countries with good sanitation, health care, and food, people live longer Life expectancy = average number of years that an individual is likely to continue to live Increases with reduced rates of infant mortality Urbanization, industrialization, and personal wealth reduce infant mortality rates Demographic transition = a model of economic and cultural change Explains the declining death and birth rates in industrializing nations

30 The demographic transition
A stable pre-industrial state of high birth and death rates changes to a stable post-industrial state of low birth and death rates As mortality decreases, there is less need for large families Parents invest in quality of life Death rates fall before birth rates Resulting in population growth

31 Human population growth and regulation

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

33 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 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 four and a half more Earths

34 Birth control: key to controlling growth
The greatest single factor slowing population growth Birth control = controlling the number of children born Reducing the frequency of pregnancy Contraception = deliberate prevention of pregnancy through a variety of methods Family planning = affects the number and spacing of children Clinics offer advice, information, and contraceptives Hindered by religious and cultural influences Rates range from 10% (Africa) to 90% (China)

35 Contraceptive methods for birth control

36 Empowering women reduces growth rates
Fertility rates drop when women gain access to contraceptives, family planning programs, and educational opportunities Women with little power have unintended pregnancies Two-thirds of the world’s illiterate are women Educating women reduces fertility rates, delays childbirth, and gives them a voice in reproductive decisions

37 Human population growth and regulation

38 Human population growth and regulation

39 We are a long way from gender equity
Over 60% of the world’s poor are women Violence against women remains shockingly common Many men resist women’s decision making The gap is obvious at high levels of government We are a long way from achieving gender equality The U.S. lags behind the world in proportion of women representatives

40 Policies and family planning work
Many countries provide incentives, education, contraception, and reproductive health care Funding and policies that encourage family planning lower population growth rates in all nations Thailand’s educational-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

41 Family planning reduces fertility rates
Blue = with family planning Red = without family planning

42 Poverty and population growth are correlated
Poorer societies have higher population growth rates Consistent with the demographic transition theory They have higher fertility and growth rates, with lower contraceptive use 99% of the next billion people added will be born in poor, less developed regions that are least able to support them

43 Correlation of poverty and population
Poverty exacerbates population growth Population growth exacerbates poverty In 1960, 70% of all people lived in developing nations As of 2010, 82% live in these nations 99% of the next billion will be born in these nations

44 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 (e.g., great apes) Africa’s Sahel and western China are turning to desert

45 Wealth also impacts the environment
The population problem is not only in poor countries Affluent societies have enormous resource consumption and waste production People use resources from other areas, as well as from their own Ecological footprints are huge We are living beyond our means One American has as much environmental impact as 4.5 Chinese or 10 Indians or 19 Afghans

46 The Earth can’t support our consumption
Biocapacity = the amount of biologically productive land and sea available to us Ecological deficit = ecological footprint > biocapacity Ecological reserve = ecological footprint < biocapacity We are running a global ecological deficit Humanity’s global ecological footprint surpassed Earth’s capacity in 1987

47 The wealth gap and population growth cause conflict
The contrast between rich and poor societies causes social and environmental stress The richest 20% use 86% of the world’s resources Increasing tensions between “haves” and “have-nots”

48 HIV/AIDS impacts African populations
The AIDS epidemic is having the greatest impact since the Black Death in the 14th century Of 33 million infected, two-thirds live in sub-Saharan Africa; 3,800 die/day Low rates of contraceptive use spread the disease HIV is established and spreading quickly around the world

49 AIDS has severe effects
AIDS undermines the ability of poor nations to develop Millions of orphans are created Fewer teachers and workers to fill jobs Families and communities break down Income and food production decline Debt and medical costs skyrocket

50 Demographic fatigue Demographic fatigue = governments face overwhelming challenges related to population growth With the added of stress of HIV/AIDS, governments are stretched beyond their capabilities Problems grow worse and citizens lose faith Good news: HIV transmission has slowed recently Decreased AIDS deaths are due to policy, collaboration, research, NGOs, and grassroots efforts

51 Sustainable development and population
Millennium Development Goals = UN’s declaration Specific targets can be met with concrete strategies Global partnerships with corporations, governments, etc. Population control is not a goal But to achieve the goals, population growth and resource consumption must be addressed

52 Millennium Development Goals

53 Conclusion The human population is larger than at any other time
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

54 QUESTION: Review What has accounted for most of the world’s population growth in recent years? a) Women are having more babies. b) Technology, medicine, and food have decreased death rates. c) Fewer women are using contraceptives. d) Nothing, the population has dropped in recent years. Answer: b

55 QUESTION: Review According to the I = P x A x T x S formula, what would happen to the impact if China’s 1 billion people had a lifestyle like Americans? a) Their population would automatically drop. b) Their population would automatically increase. c) Their affluence and technology would increase. d) Their impact on the environment would decrease. Answer: c

56 QUESTION: Review Where is the highest density of people found?
a) In the colder climates (e.g., Siberia) b) In temperate or tropical biomes c) In rural areas d) In drier areas Answer: b

57 QUESTION: Review An age structure diagram shaped like a pyramid, with a wide base shows an ________ population. a) Increasing b) Decreasing c) Stable d) Older Answer: a

58 QUESTION: Review Describe the relationship between population growth rates and population size. a) Falling growth rates automatically mean a smaller population. b) Falling growth rates automatically mean a larger population. c) Falling growth rates means we no longer have a population problem. d) Falling growth rates does not mean a smaller population, but that rates of increase are slowing. Answer: d

59 QUESTION: Weighing the Issues
Should the United States fund international family- planning efforts? a) Yes, absolutely b) Yes, but only in nations that follow U.S.-approved programs c) Only if it can influence the nations’ policies d) Never under any circumstances, it’s not our job Answer: any

60 QUESTION: Weighing the Issues
Would you rather live in a country with a larger population or smaller population? a) Small population, so there will be more resources for me b) Small population, so there will be more resources for others, including wildlife c) Large population, so I can find a date d) Large population, because people are our biggest resource Answer: any

61 QUESTION: Interpreting Graphs and Data
What happens during the “transitional” stage of the demographic transition? High birth and death rates rise - population increases High birth and death rates - population is stable High birth rates with low death rates - population increases Low birth and death rates cause - population decreases Answer: c

62 QUESTION: Interpreting Graphs and Data
According to this age pyramid, Madagascar’s future population will be: a) Balanced b) Larger c) Much larger Smaller Much smaller Answer: c

63 QUESTION: Interpreting Graphs and Data
According to these graphs, which countries had access to family planning? a) Iraq and Pakistan b) Malawi and Haiti c) Malawi and Kenya Kenya and Bangladesh Answer: c

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