13e ENVIRONMENTALSCIENCE CHAPTER 6:The Human Population and Urbanization
Global Population • http://www.youtube.com/watch?v=sc4HxPxNrZ0
Core Case Study: Are There Too Many of Us? (1) • 6.8 billion people • 83 million more each year • 2050: 9.5 billion people at current growth rates • Most growth in low-income and middle-income countries • Enough resources for growing population?
A important question • Can we provide an adequate standard of living for a projected 2.7 billion more people by 2050 without causing widespread environmental damage? • Overpopulation vs overconsumption
Core Case Study: Are There Too Many of Us? (2) • Negative viewpoint • 20% currently lack basic necessities • Declining conditions increase death rate • Increased resource use • Increased environmental degradation • Positive viewpoint • Technological solutions will increase carrying capacity • Growing population a valuable resource
Crowded street in China: largest population of all countries with 1.3 Billion people Together China and India are home to 1 of every 3 people on Earth Fig. 6-1, p. 94
6-1 How Many People Can the Earth Support? • Concept 6-1 We do not know how long we can continue increasing the earth’s carrying capacity for humans without seriously degrading the life-support system that keeps us and many other species alive.
Human Population Explosion • Exponential growth (J-curve) in past 200 years • Three major reasons • Ability to expand into diverse habitats • Emergence of agriculture • Sanitation systems and control of infectious diseases decreased death rates
How Long Can the Human Population Grow? • Rate slowing, but still exponential • Uneven global growth • No population can grow indefinitely • 2050: 9.5 billion people at current growth rates • Most growth in developing countries, least likely to cope
13 12 11 10 9 8 7 6 5 4 3 2 1 0 Exponential Growth: the J-shaped curve of past world population growth ? Industrial revolution Black Death—the Plague 2-5 million years 8000 6000 4000 2000 2000 2100 B.C. A.D. Hunting and gathering Agricultural revolution Industrial revolution Fig. 1-1, p. 1 Fig. 1-10, p. 16
UN world population projections 12 High 10.8 11 10 Medium 9.5 9 8 Population (billions) 7 Low 7.8 6 5 4 3 2 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 Year Fig. 6-2, p. 96
Natural Capital Degradation Altering Nature to Meet Our Needs Reduction of biodiversity Increasing use of the earth's net primary productivity Increasing genetic resistance of pest species and disease-causing bacteria Elimination of many natural predators Introduction of potentially harmful species into communities Using some renewable resources faster than they can be replenished Interfering with the earth's chemical cycling and energy flow processes Relying mostly on polluting and climate-changing fossil fuels Fig. 6-3, p. 97
6-2 What Factors Influence the Size of the Human Population? • Concept 6-2A Population size increases through births and immigrationand decreases through deaths and emigration. • Concept 6-2BThe average number of children born to women in a population (total fertility rate) is the key factor that determines the population size.
Population Change Population change = (births + immigration) - (deaths + emigration) Demographers look at birth rates and death rates • 2009: China, 1.3 billion people India, 1.1 billion people USA, 306 million people
Number of Children • Fertility rates affect population size and growth rate • Total fertility rate (TFR) • 1950-2009: Global TFR fell to: 1.6 from 2.5 in developed countries 2.8 from 6.5 in developing countries
Case Study: The U.S. Population Is Growing Rapidly • Quadrupled in 100 years, despite oscillations in TFR • Baby boom: High TFR • Current births outnumbering deaths and legal immigration • Growing faster than other developed countries • 2050 estimate: 439 million
TFR for US 4.0 3.5 3.0 2.5 2.1 Births per woman 2.0 1.5 Baby boom (1946–64) Replacement level 1.0 0.5 0 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Fig. 6-4, p. 98
Factors Affecting Birth Rates (1) • Importance of children as part of labor force • Cost of raising and educating children • Availability of retirement systems • Urbanization • Educational and employment opportunities for women
Factors Affecting Birth Rates (2) • Average marriage age • Availability of legal abortion and reliable birth control methods • Religious beliefs, traditions, cultural norms
Factors Affecting Death Rates • Population growth is also response to decline in crude death rate • Life expectancy and infant mortality rateimportant indicators of overall health • Average life expectancy increased • Infant mortality – barometer of a society’s quality of life
*6-3 How Does a Population’s Age Structure Affect Its Growth or Decline? • Concept 6-3The numbers of males and females in young, middle, and older age groups determine how fast populations grow or decline.
*Age Structure • Distribution of population • Prereproductive • Reproductive • Postreproductive • Country with many young people grows rapidly • Country with many older people will decline • Developing countries: >30% under 15 years old
Age Structure Predicts the Future • 36% of U.S. population baby boomers • Graying of America • Over time: increasing percentage of older baby boomers • Changes the economy
1955 1985 2015 2035 Tracking the baby-boom generation in the United States. US population by age and sex for years indicated. Stepped Art Fig. 6-8, p. 103
Declines Occur in Aging Populations • “Baby bust” or “birth dearth” – TFR below 1.5 children per couple • Labor shortages • Strain on governments for public services • Fewer taxpayers
*6-4 How Can We Slow Human Population Growth? • Concept 6-4 We can slow population growth by -reducing poverty -encouraging family planning -and elevating the status of women.
*Stages of Demographic Transition • Preindustrial • Transitional – demographic trap • Industrial • Postindustrial • Some analysts believe that most of the world’s developing countries will make a demographic transition over the next few decades, mostly because modern technology can raise per capita incomes by bringing economic development and family planning to such countries. Other analysts fear rapid pop growth, extreme poverty, and increasing environmental degradation in some low-income countries could leave them stuck in stage 2.
Stage 1 Preindustrial Stage 2 Transitional Stage 3 Industrial Stage 4 Postindustrial Population grows very slowly because of a high birth rate (to compensate for high infant mortality) and a high death rate Population grows rapidly because birth rates are high and death rates drop because of improved food production and health Population growth slows as both birth and death rates drop because of improved food production, health, and education Population growth levels off and then declines as birth rates equal and then fall below death rates 80 70 60 50 40 30 20 10 0 Total population Birth rate and death rate (number per 1,000 per year) Birth rate Death rate Low Increasing Very high Decreasing Low Zero Negative Growth rate over time Stepped Art Fig. 6-10, p. 105
Think about it • Stage 1: birth rate, death rate, population • Stage 2: birth rate, death rate, population • Stage 3: birth rate, death rate, population • Stage 4: birth rate, death rate, population
Family Planning (1) • Birth spacing, birth control, health care • Increased availability of contraception • 55% drop in TFR of developing countries • Developing countries • Almost half pregnancies unplanned • Often lack access to family planning
Family Planning (2) • Invest in family planning • Reduce poverty • Elevate the social and economic status of women
Empowering Women Can Slow Population Growth (1) • Women tend to have fewer children if they: • are educated • control their own fertility • have a paying job outside the home • do not have their rights suppressed
*Empowering Women Can Slow Population Growth (2) • Women do almost all domestic housework and childcare • Women do 60-80% of agriculture, wood gathering, water hauling • Globally, women do 2/3 of all work for 10% of income
Empowering Women Can Slow Population Growth (3) • Illiterate woman 64% of world’s population, 70% of the poor • When daughters considered less valuable, not sent to school • Poor conditions for women leads to environmental degradation
Case Study: Slowing Population Growth in China (1) • One-child families • Halved birth rate and drastically reduce TFR • Improved quality of life • Strict family planning • Sons still preferred – gender imbalance
Case Study: Slowing Population Growth in China (2) • Population rapidly aging • Rapidly growing economy • Larger middle class increases resource consumption and waste • Sustainable economic plan needed to avoid environmental degradation
Case Study: Slowing Population Growth in India • Tried to slow population growth for five decades • Most populous country in 2015 • Problems increase with growing population • Poverty • Malnutrition • Environmental degradation • Growing middle class – resource consumption
Assignment • Read Handout: “What do you think? Cultural Choices and the Rate of Population Growth” that discusses the approach to population control taken by two Indian states, Kerala and Andra Pradesh • Answer the question Which method of population control (that used by Kerala or Andra Pradesh) offers better insights and models for other countries? What are the benefits and limitations of each approach? • What do you think of the approach taken in Thailand? Why might this approach not work everywhere?
6-5 What Are the Major Urban Resource Environmental Problems? • Concept 6-5Most cities are unsustainable because of high levels of resource use, waste, pollution, and poverty.
Urban Living • Half the world lives in urban areas • 79% of Americans live in cities • 50% of world population lives in cities • Urban areas continue to grow • Natural increase • Immigration
Major Trends in Urban Growth • Proportion of urban global population growing • Number and sizes of urban areas mushrooming • Rapid increase in urban populations in developing countries • Urban growth slower in developed nations • Poverty increasing
Shows populations of 18 megacities (each with 10 million or more people) in 2009 and their projected populations in 2015. All but 3 are located in developing countries. Karachi 10.4 million 16.2 million Dhaka 13.2 million 22.8 million Beijing 10.8 million 11.7 million Tokyo 26.5 million 27.2 million New York 16.8 million 17.9 million Cairo 10.5 million 11.5 million Los Angeles 13.3 million 19.0 million Mumbai (Bombay) 16.5 million 22.6 million Osaka 11.0 million 11.0 million Calcutta 13.3 million 16.7 million Mexico City 18.3 million 20.4 million Sao Paulo 18.3 million 21.2 million Manila 10.1 million 11.5 million Lagos 12.2 million 24.4 million Jakarta 11.4 million 17.3 million Delhi 13.0 million 20.9 million Shanghai 12.8 million 13.6 million Key Buenos Aires 12.1 million 13.2 million 2004 (estimated) 2015 (projected) Fig. 6-11, p. 108
Case Study: Urbanization in the United States (1) • 1800–2009: urban population increased from 5% to 79% • Migration patterns • Rural areas to large cities • Large cities to suburbs and smaller cities • Cities and suburbs to rural areas • North and East to South and West
Almost 8 of every 10 Americans live in urban areas. Areas with names in white Are fastest growing metropolitan areas. 48% of all Americans live in cities of 1 million or more Fig. 6-12, p. 109
Urban Sprawl is a product of • Prosperity • Ample and affordable land • Automobiles • Cheap gasoline • Poor urban planning • Urban sprawl=growth of low density development on the edges of cities and towns
Urban Sprawl Problems • Increased automobile use • Decreased energy efficiency • Destruction of cropland, forests, wetlands • Economic deaths of some cities