The Human Population and Urbanization Chapter 6 Section 6-1 HOW MANY PEOPLE CAN THE EARTH SUPPORT? Human population growth continues but it is unevenly distributed • For most of history, the human population grew slowly, but has been growing exponentially for the past 200 years. Reasons for this increase in growth rate include: – Humans have expanded into almost all of the planet’s climate zones and habitats. – The emergence of early and modern agriculture allowed us to grow more food for each unit of land area farmed. – Death rates dropped sharply because of improved sanitation and health care. Human population growth continues but it is unevenly distributed • The rate of population growth has slowed, but the world’s population is still growing at a rate that added about 83 million people during 2011. • Geographically, growth is unevenly distributed. – About 1% of the 83 million new arrivals on the planet in 2011 were added to the world’s more-developed countries – The other 99% were added to the world’s middle- and low-income, less-developed countries. At least 95% of the 2.6 billion people likely to be added to the world’s population between 2011 and 2050 will end up in the least-developed countries. Annual growth of world population, 1950-2011 2.5 Average annual global growth rate (percent) 2.0 1.5 1.0 0.5 0.0 1950 1970 1990 2010 2030 2050 Year Fig. 6-2, p. 97 Human population growth continues but it is unevenly distributed • Cultural carrying capacity is the maximum number of people who could live in reasonable freedom and comfort indefinitely, without decreasing the ability of the earth to sustain future generations. Section 6-2 WHAT FACTORS INFLUENCE THE SIZE OF THE HUMAN POPULATION? The human population can grow, decline, or remain fairly stable • Birth rate, or crude birth rate, is the number of live births per 1,000 people in a population in a given year. • Death rate, or crude death rate, is the number of deaths per 1,000 people in a population in a given year. • Population change of an area = (births + immigration) - (deaths + emigration) Women are having fewer babies but not few enough to stabilize the world’s population • The total fertility rate (TFR) is the average number of children born to women in a population during their reproductive years. • Between 1955 and 2011, the average global lifetime number of births of live babies per woman dropped from 5 to 2.5. • A TFR of 2.1 will eventually halt the world’s population growth. Total fertility rates for the US between 1917-2011 4.0 Births per woman 3.5 3.0 2.5 2.1 2.0 1.5 Baby boom Replacement 1.0 (1946–64) level 0.5 0 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Fig. 6-3, p. 98 Some major changes took place in the US between 1900-2000 Life expectancy 47 years 77 years Married women working outside the 8% 81% home High school 15% graduates 83% Homes with flush 10% toilets 98% Homes with 2% electricity 99% People living in 10% suburbs 52% 1900 Hourly manufacturing $3 2000 job wage $15 Homicides per 1.2 100,000 people 5.8 Fig. 6-4, p. 99 Several factors affect birth rates and fertility rates • A particular country’s average birth rate and TFR can be affected by: – The importance of children as a part of the labor force. – The cost of raising and educating children. – The availability of, or lack of, private and public pension systems. – Urbanization. Several factors affect birth rates and fertility rates – The educational and employment opportunities available for women. – The average age at marriage. – The availability of legal abortions. – The availability of reliable birth control methods. – Religious beliefs, traditions, and cultural norms. Several factors affect death rates • People started living longer and fewer infants died because of increased food supplies and distribution, better nutrition, medical advances, improved sanitation, life expectancy, married women working, and safer water supplies. • Two useful indicators of the overall health of people in a country or region are life expectancy and infant mortality rate – The average global life expectancy increased from 48 years in 1955 to 69 years in 2011. Between 1900 and 2011, the average global life expectancy in the United States increased from 47 years to 78 years. Child laborers in India Several factors affect death rates – Infant mortality is a measure of a society’s quality of life because it reflects the general level of nutrition and health care. A high infant mortality rate can results from insufficient food (undernutrition), poor nutrition (malnutrition), and a high incidence of infectious disease, which is exacerbated by under- or malnutrition. – While infant mortality rates in more-developed and less-developed countries have declined dramatically since 1965, more than 4 million infants die during their first year of life. Several factors affect death rates – The U.S. ranks 54th in the world in infant mortality rates due to: • inadequate health care for poor women during pregnancy and for their babies after birth • drug addiction among pregnant women • a high teenage pregnancy rate Migration affects an area’s population size • Migration is the movement of people into (immigration) and out of (emigration) specific geographic areas. – Most people who migrate from one country to another are seeking jobs. – Religious persecution, ethnic conflicts, political oppression, wars, and certain types of environmental degradation are also factors. – Environmental refugees are people who migrate due to environmental degradation such as soil erosion and water and food shortages. One UN study estimated that a million people are added to this category every year. CASE STUDY: The United States: A Nation of Immigrants • Since 1820, the United States has admitted almost twice as many immigrants and refugees as all other countries combined. • Legal and illegal immigration account for about 36% of the country’s annual population growth. • Between 1820 and 1960, most legal immigrants to the United States came from Europe. Since 1960, most have come from Latin America and Asia. Hispanics are projected to make up 30% of the U.S. population by 2050. CASE STUDY: The United States: A Nation of Immigrants • There is controversy over reducing legal immigration to the U.S. – Proponents of reducing immigration say it would help stabilize population size and reduce the country’s enormous environmental impact. – Those against say it would diminish the role of the U.S. as a land of opportunity and take away from cultural diversity and innovation. Most immigrants and their descendants start new businesses and create jobs. Many immigrants take menial and low- paying jobs that most other Americans shun. CASE STUDY: The United States: A Nation of Immigrants • There were an estimated 11 million illegal immigrants in the United States in 2011. There is controversy over what to do about illegal immigration. – Some want to deport all illegal immigrants. – Others want to set up programs that allow illegal immigrants to remain in the country as long as they are working towards citizenship. Legal immigration to the US, 1820-2006 2,000 1,800 Number of legal immigrants (thousands) 1,600 1907 1,400 1914 New laws 1,200 restrict immigration 1,000 800 Great Depression 600 400 200 0 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 2010 Year Fig. 6-6, p. 101 Section 6-3 How does a population’s age structure affect its growth or decline? A population’s age structure helps us to make projections • Age structure is the numbers or percentages of males and females in young, middle, and older age groups in a given population. • Population age-structure diagrams are made by plotting the percentages or numbers of males and females in the total population in each of three age categories: – Prereproductive (0–14): normally too young to have children. – Reproductive (15–44): normally able to have children. – Postreproductive (45+): normally too old to have children. A population’s age structure helps us to make projections • Demographic momentum is rapid population growth in a country that has a large percentage of people younger than 15, and happens when a large number of girls enter their prime reproductive years. • 1.8 billion people will move into their reproductive years by 2025. • Most future human population growth will take place in less-developed countries due to their population age structure. • The global population of seniors (age 65 and older) is increasing due to declining birth rates and medical advances that have extended life spans. Generalized population age- structure diagrams Less-developed More-developed Countries Countries Male Female Male Female Male Female Male Female Expanding Rapidly Expanding Slowly Stable Declining Guatemala, Nigeria United States Japan, Italy Germany, Bulgaria Saudi Arabia Australia, China Greece Russia Prereproductive ages Reproductive ages Postreproductive ages 45–85+ 0–14 15–44 Fig. 6-7, p. 102 CASE STUDY: The American baby boom • Added 79 million people to the U.S. population 1946-1964. • The large numbers of baby boomers have strongly influenced the U.S. economy. First they created a youth market and are now creating the late middle age and senior markets. • As the baby boomers turn 65, the number of seniors will grow sharply through 2030. This process has been called the graying of America. • As the number of working adults declines in proportion to the number of seniors, so will the tax revenues necessary for supporting the growing senior population. The baby-boom generation in the US, 1955, 1985, and 2035 Populations made up mostly of older people can decline rapidly • Japan has the world’s highest % of elderly people and the world’s lowest % of young people. – Due to its discouragement of immigration, it may face a bleak economic future. • The average age of China’s population is increasing at one of the fastest rates ever recorded. This could lead to a declining work force, higher wages for workers, limited funds for supporting continued economic development, and fewer children and grandchildren to care for the growing number of elderly people. Populations can decline from a rising death rate: the AIDS tragedy • Between 1981 and 2010, AIDS killed more than 29 million people, and it takes about 2 million more lives each year (22,000 in the United States). • AIDS kills many young adults and leaves many children orphaned, causing a change in the young- adult age structure of a country. This causes a sharp drop in average life expectancy, especially in several African countries where 15–26% of the adult population is infected with HIV. • AIDS can cause a pandemic loss of productive young adult workers and trained personnel. Rapid population decline can cause several problems Some Problems with Rapid Population Decline Can threaten economic growth Labor shortages Less government revenues with fewer workers Less entrepreneurship and new business formation Less likelihood for new technology development Increasing public deficits to fund higher pension and health-care costs Pensions may be cut and retirement age increased Fig. 6-9, p. 103 Two projected age structures for Botswana’s population in 2020 100+ 95–99 90–94 85–89 80–84 75–79 70–74 65–69 60–64 55–59 Males Females Age 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 120 100 80 60 40 20 0 20 40 60 80 100 120 Population (thousands) With AIDS Without AIDS Fig. 6-10, p. 104 Section 6-4 HOW CAN WE SLOW HUMAN POPULATION GROWTH? There are three effective ways to slow population growth • The three most effective ways to slow or stop population growth are: – Reduce poverty – Elevate the status of women – Encourage family planning and reproductive health care. The demographic transition Stage 1 Stage 2 Stage 3 Stage 4 Preindustrial Transitional Industrial Postindustrial Population Population grows rapidly because Population Population growth grows very birth rates are high and death growth levels off and then slowly rates drop because of improved slows as declines as birth rates because of food production and health both birth equal and then fall (number per 1,000 per year) a high birth and death below death rates Birth rate and death rate rate (to rates drop compensate because of 80 for high improved 70 infant Total population 60 mortality) food and a high Birth rate production, 50 death rate health, and 40 education 30 20 Death rate 10 0 Low Increasing Very high Decreasing Low Zero Negative Growth rate over time Fig. 6-11, p. 105 Promote economic development • As countries become industrialized and economically developed, their populations tend to grow more slowly. This demographic transition has four phases: – Preindustrial – Transitional – Industrial – Postindustrial Promote economic development • Less-developed countries may transition to slower growth if modern technology can raise per capita incomes by bringing economic development and family planning. • Rapid population growth, extreme poverty, and increasing environmental degradation in some low-income less-developed countries— especially in Africa—could leave these countries stuck in stage 2 of the demographic transition. Empowering women can slow population growth • Women tend to have fewer children if they are educated, have the ability to control their own fertility, hold a paying job outside the home, and live in societies that do not suppress their rights. • Women account for 66% of all hours worked but receive only 10% of the world’s income and own just 2% of the world’s land. • Women make up 70% of the world’s poor and 64% of its 800 million illiterate adults. • Poor women who cannot read often have an average of 5–7 children, compared to 2 or fewer children in societies where almost all women can read. Women of a village in Burkina Faso Promote family planning • Family planning provides educational and clinical services that help couples choose how many children to have and when to have them. • Successes of family planning: – Without family planning programs that began in the 1970s, the world’s population would be about 8.5 billion instead of the current 7 billion. – Family planning has reduced the number of abortions performed each year and decreased the numbers of mothers and fetuses dying during pregnancy. Promote family planning • Problems that have hindered success in some countries: – 42% of all pregnancies in less-developed countries are unplanned and 26% end with abortion. – An estimated 201 million couples in less- developed countries want to limit their number of children, but lack access to family planning services. CASE STUDY: Slowing Population Growth in India • For over 50 years, India has tried to control its population growth with only modest success. • Two factors help account for larger families in India. – Most poor couples believe they need several children to work and care for them in old age. – The strong cultural preference for male children means that some couples keep having children until they produce one or more boys. • The result: even though 9/10 Indian couples have access to at least one modern birth control method, only 48% actually use one. Four of every ten people in India struggle to live on the equivalent of less than $1.25 /day Section 6-5 WHAT ARE THE MAJOR URBAN RESOURCE AND ENVIRONMENTAL PROBLEMS? Scientists see three important urban trends • An increasing percentage of the world’s people live in urban areas. • Urban areas grow in two ways—by natural increase due to births and by immigration, mostly from rural areas. • Three major trends in urban population dynamics have emerged: – The proportion of the global population living in urban areas increased from 2% in 1850 to 50% today, and is projected to be 70% by 2050. Scientists see three important urban trends – The numbers and sizes of urban areas are mushrooming. We now have cities with 10 million or more people (megacities or megalopolises) and will soon have hypercities with more than 20 million people. Megacities and hypercities are merging into megaregions that can stretch across entire countries. – Poverty is becoming increasingly urbanized, mostly in less-developed countries. An estimated 1 billion people in less-developed countries live in urban slums and shantytowns. Major urban areas throughout the world – city lights at night Delhi Hong Kong Beijing Shanghai Moscow 18.6 million 15.8 million 22 million 17 million 15 million Tokyo London Los Angeles 36 million 12.9 million 15.2 million New York 19.7 million Cairo Osaka 14.5 million 17.4 million Mexico City Karachi Seoul 20.5 million Lagos 12.2 million 20.6 million 13.4 million Manila Kolkata Rio de Janeiro 16.3 million (Calcutta) 12 million 15.1 million Bangkok São Paulo Mumbai 12 million 18.9 million (Bombay) Jakarta Dhaka Buenos Aires 19.2 million 18.9 million 13 million 13.1 million Fig. 6-14, p. 108 CASE STUDY: Urbanization in the United States • Between 1800-2011, the % of the U.S. population living in urban areas increased from 5% to 79%. This population shift has occurred in four phases. – People migrated from rural areas to large central cities. – Many people migrated from large central cities to smaller cities and suburbs. – Many people migrated from the North and East to the South and West. – Some people fled cities and moved to developed areas outside of suburbs. These exurbs are scattered over vast areas that lie beyond suburbs and have no socio- economic centers. CASE STUDY: Urbanization in the United States • There are upsides to urbanization. Conditions in U.S. cities have improved, with better working and housing conditions, improved air and water quality, and decreased death rates and sickness from infectious diseases due to better sanitation, clean public water supplies, and medical care. • Concentrating people in urban areas has helped protect the country’s biodiversity by reducing the destruction and degradation of wildlife habitat. • Many cities have aging infrastructures (streets, bridges, dams, power lines, schools, waste management, water supply pipes, and sewers) with limited funds for repair. Urban areas in the US with more than 1 million people Urban sprawl in and around Las Vegas, NV, 1973 and 2009 1973 2009 Urban sprawl gobbles up the countryside • Urban sprawl, or the growth of low-density development on the edges of cities and towns, is eliminating surrounding agricultural and wild lands. • Urban sprawl is the product of affordable land, automobiles, relatively cheap gasoline, and poor urban planning. Urban sprawl gobbles up the countryside • Urban sprawl has caused or contributed to a number of environmental problems. – People are forced to drive everywhere, resulting in more emission of greenhouse gases and air pollution. – Sprawl has decreased energy efficiency, increased traffic congestion, and destroyed prime cropland, forests, and wetlands. – Sprawl has led to the economic deaths of many central cities as people and businesses move out. Urban sprawl Urbanization has advantages • Cities are centers of industry, commerce, transportation, innovation, education, technological advances, and jobs. • Urban residents in many parts of the world tend to live longer than do rural residents, and have lower infant mortality and fertility rates. • Cities provide better access to medical care, family planning, education, and social services. • Recycling is more economically feasible. • Concentrating people in cities helps to preserve biodiversity. • Central cities can save energy if residents rely more on energy efficient mass transportation, walking, and bicycling. Urbanization has disadvantages • Most urban areas are unsustainable systems. – The typical city depends on large non-urban areas for huge inputs of matter and energy resources, while it generates large outputs of waste matter and heat. • Most cities lack vegetation. – Destroyed vegetation could have absorbed air pollutants, given off oxygen, provided shade, reduced soil erosion, provided wildlife habitats, and offered aesthetic pleasure. • Many cities have water problems. – Providing water to cities can deprive rural and wild areas of surface water and can deplete underground water supplies. Urbanization has disadvantages – Cities in arid areas that depend on water withdrawn from rivers and reservoirs behind dams will face increasing problems. – Cities can have flooding problems for several reasons: • Being built on floodplains or near low-lying coastlines. • Covering land with buildings, asphalt, and concrete causes precipitation to run off quickly and overload storm drains. Urbanization has disadvantages – Destroying or degraded large areas of wetlands that have served as natural sponges to help absorb excess storm water. – Flooding as sea levels rise because of projected climate. • Cities in arid areas that depend on water bodies fed by mountaintop glaciers will face water shortages if global warming melts the glaciers. Urban areas are rarely sustainable systems Inputs Outputs Energy Solid wastes Food Waste heat Air pollutants Water Water pollutants Raw materials Greenhouse gases Manufactured Manufactured goods goods Noise Money Wealth Information Ideas Fig. 6-18, p. 110 Cities tend to concentrate pollution and health problems • Cities produce most of the world’s air pollution, water pollution, and solid and hazardous wastes. • High population densities can increase the spread of infectious diseases, especially if adequate drinking water and sewage systems are not available. Cities affect local climates • Cities tend to be warmer, rainier, foggier, and cloudier. • Heat generated by cars, factories, furnaces, lights, air conditioners, and heat- absorbing dark roofs and streets creates an urban heat island surrounded by cooler suburban and rural areas. • The artificial light created by cities affects some plant and animal species. Life is a desperate struggle for the urban poor in less-developed countries • At least 1 billion people live under crowded and unsanitary conditions in cities in less-developed countries. • Slums are areas dominated by tenements and rooming houses where several people might live in a single room. • Squatter settlements and shantytowns are on the outskirts of cities, and usually lack clean water supplies, sewers, electricity, and roads, and are subject to severe air and water pollution and hazardous wastes from nearby factories. CASE STUDY: Mexico City • The world’s second most populous city suffers from severe air pollution, high unemployment, noise, overcrowding, traffic congestion, inadequate public transportation, and a soaring crime rate. More than one-third of its residents live in slums or squatter settlements that lack running water, electricity and sewage facilities. • Air and water pollution cause an estimated 100,000 premature deaths per year. CASE STUDY: Mexico City • The severity of air pollution has been reduced by banning cars in its central zone, requiring air pollution controls on newer cars, phasing out leaded gasoline, and encouraging purchase of buses, taxis, and delivery truck that produce fewer emissions. The city also bought land for use as green space and planted more than 25 million trees to help absorb pollutants. Section 6-6 HOW DOES TRANSPORTATION AFFECT URBAN ENVIRONMENTAL IMPACTS? Cities can grow outward or upward • Most people living in compact cities such as Hong Kong, China, and Tokyo, Japan, get around by walking, biking, or using mass transit such as rail or buses. • In countries such as the United States, Canada and Australia, plentiful land and networks of highways have produced dispersed cities whose residents depend on motor vehicles for most travel. Cities can grow outward or upward • Largely because of urban sprawl, all Americans combined drive about the same distance each year as the total distance driven by all other drivers in the world, and in the process use about 43% of the world’s gasoline. Motor vehicles have advantages and disadvantages • They provide mobility and offer convenient and comfortable transportation. • They can be symbols of power, sex appeal, social status, and success. • Much of the world’s economy is built on producing motor vehicles and supplying fuel, roads, services, and repairs for them. • Globally, automobile accidents kill approximately 1.2 million people a year and injure another 15 million people. Motor vehicles have advantages and disadvantages • They kill about 50 million wild animals and family pets every year. • Motor vehicles are the world’s largest source of outdoor air pollution. • They are the fastest-growing source of climate- changing CO2 emissions. • At least a third of the world’s urban land and half of that in the United States is devoted to roads, parking lots, gasoline stations, and other automobile-related uses. • People waste time sitting in traffic congestion. Reducing automobile use is not easy, but it can be done • A user-pays approach makes drivers pay directly for most of the environmental and health costs caused by their automobile use. – An example of full-cost pricing is a tax on gasoline that covers the estimated harmful costs of driving. – Gasoline revenues could be used to help finance alternatives to cars. – Taxing gasoline heavily would be difficult in the U.S. for several reasons. • Strong opposition from the public, and from transportation- related industries. • The dispersed nature of most U.S. urban areas. • Lack of fast, efficient, reliable, affordable mass transit options. Reducing automobile use is not easy, but it can be done • Raise parking fees and charge tolls on roads, tunnels, and bridges leading into cities, especially during peak traffic times. • Some cities promote car-sharing networks, which bill members monthly for the time they use a car and the distance they travel, and can decrease car ownership. Some cities promote alternatives to cars • The following are alternatives to cars, each with its own advantages and disadvantages: – Bicycles – Mass-transit rail systems in urban areas – Bus systems in urban areas – High-speed rail systems between urban areas (bullet trains) Alternatives to cars Section 6-7 HOW CAN CITIES BECOME MORE SUSTAINABLE AND LIVABLE? We can make urban areas more environmentally sustainable and enjoyable places to live • Smart growth encourages environmentally sustainable development requiring less dependence on cars, controls and directs sprawl, and reduces wasteful resource use, by using zoning laws and other tools to channel growth into areas where it can cause less harm. • New urbanism involves less-developed villages within cities, so that people can live within walking distance of where the work, shop, and go for entertainment Smart growth tools CASE STUDY: The new urban village of Vauban • Vauban is a suburb outside the city of Freiberg, Germany that is virtually free of cars. • Street parking, driveways, and garages are generally forbidden in the village. A parking space in a city garage costs $40,000. • Homes are within easy walking distance of trains, stores, banks, restaurants, and schools. There are numerous bike paths and a car-sharing club. Mass transit allows residents to work or shop in the city of Freiburg. • There are no single-family homes, only energy- efficient row houses that use passive solar energy. CASE STUDY: The new urban village of Vauban • An ecocity emphasizes the following goals: – Use solar and other locally available, renewable energy resources and design buildings to be heated and cooled as much as possible by nature. – Build and redesign cities for people, not cars. – Reduce the waste of matter and energy. – Prevent pollution. – Reuse, recycle, and compost 60–85% of all municipal solid waste. – Protect and encourage biodiversity by preserving undeveloped land and protecting and restoring natural systems and wetlands in and around cities. – Promote urban gardens and farmers markets. – Use zoning and other tools to keep urban sprawl at environmentally sustainable levels. CASE STUDY: The new urban village of Vauban • Current examples of ecocities include Curitiba, Brazil; Bogotá, Colombia; Waitakere City, New Zealand; Stockholm, Sweden; Helsinki, Finland; Leicester, England; Neerlands, the Netherlands; and in the United States, Portland, Oregon; Davis, California; Olympia, Washington; and Chattanooga, Tennessee CASE STUDY: The ecocity concept in Curitiba, Brazil • A city of 3.2 million people known as the “ecological capital” of Brazil. • Planners in this city in 1969 focused on an inexpensive and efficient mass transit system rather than on the car. • Only high-rise apartment buildings are allowed near major bus routes, and each building must devote its bottom two floors to stores, reducing the need for residents to travel. • Cars are banned from the downtown area, which has a network of pedestrian walkways connected to bus stations, parks, and bicycle paths running throughout most of the city. CASE STUDY: The ecocity concept in Curitiba, Brazil • The city transformed flood-prone areas along its six rivers into a series of interconnected parks. • Curitiba recycles roughly 70% of its paper and 60% of its metal, glass, and plastic. Recovered materials are sold mostly to the city’s more than 500 major industries, which must meet strict pollution standards. • The poor receive free medical and dental care, child care, and job training, and 40 feeding centers are available for street children. • About 95% of Curitiba’s citizens can read and write and 83% of its adults have at least a high school education. All school children study ecology. CASE STUDY: The ecocity concept in Curitiba, Brazil • The city transformed flood-prone areas along its six rivers into a series of interconnected parks. • Curitiba recycles roughly 70% of its paper and 60% of its metal, glass, and plastic. Recovered materials are sold mostly to the city’s more than 500 major industries, which must meet strict pollution standards. • The poor receive free medical and dental care, child care, and job training, and 40 feeding centers are available for street children. • About 95% of Curitiba’s citizens can read and write and 83% of its adults have at least a high school education. All school children study ecology. Bus rapid-transit (BRT) system in Curitiba, Brazil Three big ideas • The human population is increasing rapidly and may soon bump up against environmental limits. • We can slow human population growth by reducing poverty, encouraging family planning, and elevating the status of women. • Most urban areas are unsustainable, but they can be made more sustainable and livable within your lifetime.
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