Transcript
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 Central Case Study: China’s One-Child Policy In 1970, China’s 790 million people were exhausting their resources and faced starvation if growth continued The government instituted a one-child policy The growth rate plummeted The policy is now less strict The successful program has had unintended consequences Killing of female infants and an imbalance in male to female ratios Increasing number of elderly and fewer young people in the workforce Our World at Seven Billion Populations continue to rise in most countries, particularly in poverty-stricken developing nations Growth in poorer nations leads to stresses on society, the environment, and people’s well-being China’s stringent policies have greatly slowed growth there, but other countries may wish to slow their growth without the measures used by China India’s growth continues and if not changed will surpass China’s population 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 Our population grows by over 70 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 Growth rates vary from country to country Some countries are over 3%, while other country’s populations are shrinking The current world growth rate is 1.2% At this rate, the human population of the planet would double in 58.3 years Is population growth a problem? Better technology, sanitation, medication, and increased food supply have increased growth Death rates drop, but not birth rates Infant mortality rate = the death rate in children; has dropped dramatically Population growth was seen as good Support for elderly, a larger labor pool Thomas Malthus’s An Essay on the Principles of Population (1798) Humans will outstrip food supplies War, disease, starvation reduce populations Is population growth a problem? Neo-Malthusians: population growth will increase faster than food production; cause famine and conflict Paul Ehrlich’s Population Bomb (1968) predicted that civilization would end by the end of the 20th century Intensified food production fed more people Cornucopians argue that we will continue to find new resources and technology to support people Environmental scientists argue that there are finite resources Land is limited, extinct species are gone forever Quality of life will suffer with unchecked growth Less space, food, wealth per person Some national governments now 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 66% of European governments think their birth rate is too low 49% of non-European nations feel their birth rates are too high Population is one of several factors that affect 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, but also pollution controls and renewable energy Sensitivity (S) = how sensitive an area is to human pressure (e.g., arid land vs. rainforest) Further model refinements include the effects of education, laws, and ethics on the formula Population is one of several factors that affect the environment 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 Modeling Population Growth— Human Population Growth and Regulation 2 Right-click/Select Play Modeling Population Growth— Human Population Growth and Regulation 1 Right-click/Select Play 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 There is a carrying capacity for all species, including humans Humans raise the environment’s carrying capacity through technology How many humans can the world sustain? 1 billion to 33 billion: prosperity to abject poverty Population growth can’t continue forever Demography is the study of human population Demographers study: Population size Density and distribution Age structure Sex ratio Birth, death, immigration, and emigration rates Population size Current world population is just over 7 billion Estimated to grow to over 9 billion by 2015 Population density and distribution Population size alone does not tell whole story People are not distributed equally over the planet (clumped distribution) Highest density: temperate, subtropical, tropical biomes and close to water Cities are local high-density areas Lowest density: away from water, extreme environments Increased density impacts the environment Age structure Age structure describes the relative numbers in each age class within a population Age structure diagrams (population pyramids) show age structure Wide base denotes many young High reproduction, rapid population growth Even age distribution: remains stable as births keep pace with deaths Narrow base denotes fewer young than old Population will likely decline over time Age structure Many populations are getting older Median global age today is 28, but it will be 38 by 2050 The elderly will need care and financial assistance Taxes will increase for Social Security and Medicare But fewer dependent children may mean lower crime rates, and the elderly can remain productive Age structure 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 to assist the elderly Sex ratios Unequal sex ratios can impact population growth Human sex ratios at birth slightly favor males For every 100 females born, 106 males are born In China, 120 boys were reported for 100 girls Culture values males over females The government’s one-child policy Females have been selectively aborted The undesirable social consequences? Many single Chinese men Increased risk of HIV Teenage girls are kidnapped and sold as brides Population change results from birth, death, immigration, and emigration 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 Population change results from birth, death, immigration, and emigration Immigration/emigration have become more important 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 Overall global growth rate has declined in recent years But world population continues to grow Total fertility rate influences population growth 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) TFR has been decreasing in many nations due to: Industrialization Improved women’s rights Quality health care In Europe as a whole, TFR is now 1.6 Natural rate of population change = change due to birth and death rates alone (no migration) Many nations are experiencing the demographic transition 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 Has increased with reduced rates of infant mortality Demographic transition = a model of economic and cultural change Explains the declining death and birth rates in industrializing nations Populations undergo four stages Many nations are experiencing the demographic transition Pre-industrial stage = in pre-industrial societies, both birth and death rates are high High birth rate to compensate for high infant mortality Population growth is slow Transitional stage = declining death rates due to increased food production and medical care Birth rates remain high since people are not used to the low infant mortality rates Population grows quickly Modeling Population Growth— Human Population Growth and Regulation 4 Right-click/Select Play Many nations are experiencing the demographic transition Industrial stage = birth rates fall as jobs provide opportunities for women outside the home and children are not needed in the workforce Difference between birth and death rates shrinks Population growth slows Post-industrial stage = birth and death rates are low and stable Population stabilizes or even shrinks Is the demographic transition a universal process? 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 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 Population and Society Many factors affect fertility in a given society: Access to family planning Rates of infant mortality Levels of women’s rights Level of affluence Importance of child labor Government support for retirees Family planning is a key approach for controlling growth Family planning = efforts to control the number and spacing of children; the greatest single factor slowing population growth Clinics offer advice, information, and contraceptives Birth control = effort to control the number of children born by reducing the frequency of pregnancy Contraception = deliberate prevention of pregnancy through a variety of methods Rates range from less than 10% (14 countries in Africa) to 84% (China) Family planning is a key approach for controlling growth Low use of family planning may have different causes Rural areas may have limited availability Religious doctrines or cultural influences may reject family planning Family planning gives women control over their reproductive window = time frame where a woman can become pregnant Potential to produce 25 children during the window Family planning may delay first reproduction, space births, or “close” the window when desired family size is achieved Family-planning programs are working around the world Funding and policies that encourage family planning lower population growth rates in all nations, regardless of level of industrialization Thailand’s educational-based approach to family planning reduced its growth rate from 2.3% to 0.5% Brazil, Mexico, Iran, Cuba, and other developing countries have active programs These entail setting targets and providing incentives, education, contraception, and reproductive health care Empowering women reduces fertility rates Where women are freer to decide whether and when to have children, fertility rates fall, and children are better cared for, healthier, and better educated. Fertility rates drop most noticeably when women gain access to contraceptives and family-planning programs As women receive educational opportunities, fertility rates decline Two-thirds of the world’s illiterate are women Education leads to delayed childbirth as women pursue careers Modeling Population Growth— Human Population Growth and Regulation 3 Right-click/Select Play Modeling Population Growth— Human Population Growth and Regulation 5 Right-click/Select Play Increasing affluence lowers fertility Poorer societies have higher population growth rates Consistent with the demographic transition theory High fertility to ensure some children would survive and be able to contribute to farm labor More affluent societies can provide: Better medical care, reducing infant mortality Education for children (removing them from the workforce and making them an economic liability) Social security for the elderly Educational opportunities for women Increasing affluence lowers fertility 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 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) Expanding wealth can increase the environmental impact per person 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 People in affluent societies have larger ecological footprints One American has as much environmental impact as 3.8 Chinese or 8 Indians or 14 Afghans Not only is the world population increasing, but the consumption per person is also rising Expanding wealth can increase the environmental impact per person 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 exceeds biocapacity by 50% The richest 20% of the world’s population uses 86% of the world’s resources HIV/AIDS is exerting major impacts on African populations The AIDS epidemic is having the greatest impact since the Black Death in the 14th century Of 34 million infected, two-thirds live in sub-Saharan Africa; 3800 die/day Low rates of contraceptive use spread the disease Infant mortality is 14 times that of the developed world Life expectancy has dropped from 60 years in the 1990s to 40–50 years today HIV is also well established in the Caribbean and in Southeast Asia, and it is spreading in eastern Europe and central Asia Demographic change has social and economic repercussions AIDS undermines the ability of poor nations to develop Removes productive members of society Cost of medical treatment is a huge burden Millions of orphans require government services Demographic change has social and economic repercussions Demographic fatigue = occurs when governments face overwhelming challenges related to population growth With the added stress of HIV/AIDS, governments are stretched beyond their capabilities Problems grow worse and citizens lose faith Good news: HIV transmission has slowed recently Population goals support sustainable development 1994 UN conference on population and development Rejected top-down, command-and-control approaches that pushed contraceptives and preset targets Urged education and health care Urged addressing social needs (like poverty, sexism) from the bottom up To generate a high quality of life for all people, developing nations must slow population growth Developed nations must reduce resource consumption 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 and leave a quality world QUESTION: Review What has accounted for most of the world’s population growth in recent years? Women are having more babies. Technology, medicine, and food have decreased death rates. Fewer women are using contraceptives. Nothing; the population has dropped in recent years. QUESTION: Review According to the I = P ? A ? T ? S formula, what would happen if China’s 1 billion people had a lifestyle like that of 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. QUESTION: Review Where is the highest density of people found? In the colder climates (e.g., Siberia) In temperate or tropical biomes In rural areas In drier areas QUESTION: Review An age structure diagram shaped like a pyramid with a wide base shows a/an ________ population. increasing decreasing stable older QUESTION: Review Describe the relationship between population growth rates and population size. Falling growth rates automatically mean a smaller population. Falling growth rates automatically mean a larger population. Falling growth rates mean we no longer have a population problem. Falling growth rates do not mean a smaller population, but that rates of increase are slowing. QUESTION: Review Pre-industrial societies tend to have higher growth rates because good medical care prevents infant mortality. there is little opportunity for women to get an education or employment. governments provide social support networks for the elderly. children are required to attend school. QUESTION: Weighing the Issues Should the United States fund international family- planning efforts? Yes, absolutely. Yes, but only in nations that follow U.S.-approved programs. Only if it can influence the nations’ policies. Never under any circumstances; it’s not our job. QUESTION: Weighing the Issues Would you rather live in a country with a larger population or smaller population? Small population, so there will be more resources for me Small population, so there will be more resources for others, including wildlife Large population, so I can find a date Large population, because people are our biggest resource 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 QUESTION: Interpreting Graphs and Data According to this age pyramid, Nigeria’s future population will be balanced. larger. much larger. smaller. much smaller. QUESTION: Interpreting Graphs and Data According to these graphs, which countries had access to family planning? Iraq and Pakistan c) Malawi and Kenya Malawi and Haiti d) Kenya and Bangladesh
