This lecture will help you understand: Case study: China s one-child policy. Our world at seven billion. Rates of growth vary from region to region

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1 This lecture will help you understand: Lecture Outlines Chapter 8 Environment: The Science behind the Stories 4th Edition Withgott/Brennan 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 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 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! The human population is growing rapidly Rates of growth vary from region to region 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 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

2 Is population growth a problem? Industrial revolution: 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 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 Some governments fear falling populations Will population growth affect our quality of life? 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 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 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 2

3 Human population growth and regulation What is the Earth s carrying capacity? 1 billion? 6 billion? 33 billion? Demography Demographers study: 1. Population size 2. Density and distribution 3. Age structure 4. Sex ratio 5. Birth, death, immigration, and emigration rates Population size, density, and distribution 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 Humans are unevenly distributed around the globe Population density and distribution 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 3

4 Age structures: Canada vs. Madagascar 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 Canada s age structure is balanced Madagascar s age structure is heavily weighted toward the young 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 Sex ratios Human sex ratios at birth slightly favor males - For every 100 females born, 106 males are born Chinese females are selectively aborted 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 What factors affect human population growth? Whether a population grows, shrinks, or remains stable depends on: - BIDE factors (birth, immigration, death, emigration) - Growth rate = (births + immigration) - (deaths + emigration) In human societies, technological advances lead to declines in human death rates. If birth rates remain constant and death rates drop? the population growth rate increases Total Fertility Rate Total fertility rate (TFR) is perhaps the most important parameter governing population growth TFR is defined as the average number of children born per female during her lifetime Since TFR is such an important part of population growth, understanding factors that influence TFR can shed light on ways in which we can regulate population growth. Replacement fertility is defined as that TFR that keeps the size of a population stable (AKA: ZPG or Zero Population Growth) - For humans, replacement fertility = When TFR is <2.1 population size, in the absence of immigration, and assuming a stable age distribution, will decrease 4

5 Factors Decreasing Total Fertility Rate Improved Medical Care: - Historically, people tended to conceive many children to ensure that at least some would survive - As medical care improved, and infant mortality rates dropped, TFR dropped as well Urbanization: - Rural families need children to contribute to farm labor - In urban areas children are usually excluded from the labor pool Factors Decreasing Total Fertility Rate Social Security: - In countries where the government provides some form of social security, parents need fewer children to support them in their old age Educating Women: - Perhaps the single most important factor that acts to reduce TFR is an educated female population - Access to educational opportunities, contraception, and family planning programs allows women to exert control of their reproductive destiny and choose both the spacing and number of children they bear - Women with little power have unintended pregnancies: two-thirds of the world s illiterate are women A woman's educational level is the best predictor of how many children she will have Worldwide, total fertility varies widely The previously listed factors have come together in Europe where TFR has dropped from 2.6 to 1.5 since 1960 Every European nation now has a TFR < replacement level In 2007, 71 countries (encompassing 45% of world population) had fallen below replacement level TFR The demographic transition The demographic transition s four stages Most of the nations with a TFR less than replacement level have undergone a common set of changes Good sanitation, effective health care, reliable food supplies, an accessible education system, and decreased infant mortality all generally coincide with increasing urbanization and industrialization This common set of changes as a nation urbanizes and industrialized, and the coincident reduction in TFR is part of the Demographic Transition Population growth is seen as a temporary phenomenon 5

6 Is the demographic transition universal? It has occurred in Europe, the U.S., Canada, Japan, and other nations over the past 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 Birth control: key to controlling growth The greatest single factor slowing population growth Family planning = affects the number and spacing of children - Clinics offer advice, information, and contraceptives - Hindered by religious and cultural influences - Participation rates range from 10% (Africa) to 90% (China) 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 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 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 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 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 6

7 The Earth can t support our consuming lifestyle 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 It is estimated that humanity s global ecological footprint surpassed Earth s capacity to support us in 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 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 Sustainable development and population Millennium Development Goals Millennium Development Goals = UN s 2000 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 7

8 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 8