Chapter 6: Human Population Central Case Study: China’s ... · PDF file06.10.2012 · © 2012 Pearson Education, Inc. Chapter 6: Human Population •Human population...

© 2012 Pearson Education, Inc.

Chapter 6: Human Population

• Human population growth• Population, affluence, and technology’s effects• Demography• Demographic

transition• Factors affecting

population growth


Central Case Study: China’s One-ChildPolicy

• In 1970, China’s 790 millionpeople faced starvation

• The government instituted aone-child policy– The growth rate plummeted

• The policy is now less strictbut has unwanted consequences:– Killing of female infants– Black-market trade in teenaged

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 stillincreasing in numbers

Counting to 1 billion(1/second) would take 31years—it would take 221years to count to 7 billion!


The human population is growing rapidly

• Our population grows by over 80 million each year• It took until 1800 to reach 1 billion• We added 6 more billion in 130 years• We added the most

recent billion in 12 years

Because of exponentialgrowth (increase by a fixed%), even if the growth rateremains steady, populationwill continue to grow


Growth rates vary from region to region

• At today’s 1.2% global growth rate, the population willdouble in 58 years (70/1.2 = 58)

• If China’s rate had continued at 2.8%, it would havehad 2 billion people within 25 years


Is there a limit to population growth?

• Technology, sanitation, medication, and food increasepopulation– Death rates drop, but not birth rates

• Earth’s carrying capacity for people?– 2 billion prosperous people

– 33 billion very poor people

• Thomas Malthus’ An Essay on the Principles ofPopulation (1798)– War, disease, starvation will reduce populations


Different views on population growth

• Paul Ehrlich’s The Population Bomb (1968) predictedthat population growth would lead to famine and conflict– But intensified food production fed more people

• Many economists think depleted resources will bereplaced or new resources created– But many resources (e.g., species) cannot be replaced

• Quality of life will suffer with unchecked growth– Less space, food, wealth per person

• Population growth is a problem if it depletes resources,stresses social systems, and degrades the environment


Population growth: causes andconsequences


Several factors affect the environment

• The IPAT model: I = P × A × T• Our total impact (I) on the environment results from:

– Population (P): individuals need space and resources– Affluence (A): per capita resource use– Technology (T): increases use of, or protects, resources

• Sensitivity (S): a fourth factor showing how sensitive anarea is to human pressure

• Further model refinements include the effects ofeducation, laws, and ethics on the formula


China is an example of the IPAT formula

• Elements of the IPAT equation can combine– Causing tremendous impact in a very short time

• Modern China’s rapid development is causingunprecedented environmental challenges– Intensive agriculture is eroding farmland

– Overuse has dried up the mighty Yellow River

– Increasing vehicles are causing urban pollution andmassive traffic jams


Demography

• Demographers study:– Population size– Density and

distribution– Age structure– Sex ratio– Birth, death,

immigration, andemigration rates

• Demography: applying the principles of populationecology to the study of change in human populations


Population size and density

• The UN predicts 9 billion humans by 2050• Highest density: temperate, subtropical, tropical biomes

– Coasts, rivers, cities• Lowest density: extreme climates (desert, rainforest,

tundra)– Also, areas away from water

If women have just 0.5child fewer than themedium scenario, there willbe 8, not 9.15, billion by2050


Population distribution

• Humans are unevenly distributed around the globe• Many unpopulated areas (e.g., deserts, arid grasslands) are

environmentally sensitive– High S value in the modified IPAT equation– Vulnerable to humans (agriculture, ranching, etc.)


Age structure affects population size

• Age structure: describes relative numbers of individuals ineach age class– Shown by age structure diagrams (population pyramids)

• Wide base: has many young that haven’t reproduced yet– Population will soon grow rapidly

• Even age distribution:– Remains stable– Births = deaths


Canada’s age structure isbalanced (growth rate =0.4%)

Madagascar’s age structureis heavily weighted towardthe young (growth rate =2.9%)

Age structures: Canada vs. Madagascar


Many populations are aging• The global mean age is now 28—in 2050, it will be 38• China’s age structure is changing

– In 1970, the medianage was 20

– By 2050, itwill be 45

Although fewerpeople will beworking to supportsocial programs,the elderly canremain productive


Factors in population change

• Rates of birth, death, and migration determine whethera population grows, shrinks, or remains stable– Birth and immigration add individuals– Death and emigration remove individuals

• Technological advances cause decreased deaths– The increased gap between birth and death rates resulted

in population expansion• Natural rate of population change: change due to

birth and death rates alone, excluding migration


Falling growth rates do not mean fewerpeople

Despite falling growthrates, the populationcontinues growing by

adding 80 millionpeople each year


Factors affecting total fertility rate

• Total fertility rate (TFR): the average number ofchildren born to each female during her lifetime

• Replacement fertility: the TFR that keeps the size ofa 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


Life expectancy is increasing

• People live longer in countries with good sanitation,health care, and food

• Urbanization, industrialization, and personal wealthreduces rates of infant mortality– Which increases life expectancy (the time a person can

expect to live)

• Demographic transition: a model of economic andcultural change– Explains the declining death and birth rates in

industrializing nations


The demographic transition

• As they industrialize, nations move from a stable pre-industrial state of high birth and death rates– To a stable post-industrial state of low birth and death

rates

• Industrialization decreases mortality rates– So there is less need for large families

– Parents invest in quality of life, not quantity of kids

• Death rates fall before birth rates– Resulting in temporary population growth


The 4 stages of the demographic transition

• Pre-industrial stage: low population growth– High death (disease, starvation, few medicines) and birth

(compensation for mortality) rates

• Transitional stage: industrialization, increased food andmedical care reduce mortality rates– High birth rates cause population to surge

• Industrial stage: women get jobs and use birth control– Kids do not need to help get food

• Post-industrial stage: low birth and death rates stabilizepopulations


The demographic transition’s four stages

Population growth is seen as a temporary phenomenon© 2012 Pearson Education, Inc.

Is the demographic transition universal?

• It has occurred in Europe, the U.S., Canada, Japan, andother nations over the past 200–300 years– But it may or may not apply to developing nations

• The transition could fail:– If the population is too large to allow the transition– In cultures that place greater value on childbirth or grant

women fewer freedoms

For people to attain the material standard of living ofNorth Americans, we would need the natural resources of

4.5 more Earths


Family planning: key to controlling growth

• Family planning: efforts to plan the number and spacingof children– The greatest single factor slowing population growth

– Clinics offer advice, information, and contraceptives

• Birth control: controlling the number of children born byreducing the frequency of pregnancy

• Contraception: deliberate prevention of pregnancythrough a variety of methods– Hindered by religious and cultural influences

– Rates range from 10% (Africa) to 86% (China)© 2012 Pearson Education, Inc.

Empowering women reduces fertility rates

• A nation’s fertility rates drop when women gain access– To contraceptives, family planning programs, and

educational opportunities• Women need control over

their reproductive window:– The time in their lives

when they can becomepregnant

Educating women reducesfertility rates, delayschildbirth, and gives them avoice in reproductive decisions


Policies and family planning work

• Funding and policies that encourage family planninglower population growth rates in all nations

• Thailand’s education-based approach to family planningreduced 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– Offer education, health care, and address social needs– Global funding has fallen 33%, slowing progress


Family planning reduces fertility rates

Blue: withfamily planning

Red: withoutfamily planning


Poverty and population growth are correlated

• Poor societies havehigher populationgrowth rates

• Poverty andpopulation growthmake each otherworse

99% of the next billion people added will be born inpoor, less developed regions that are least able to

support them© 2012 Pearson Education, Inc.

Poverty causes environmental degradation

• Population growth in poor nations increasesenvironmental degradation– Farming degrades soil in arid areas (Africa, China)– Poor people cut forests,

deplete biodiversity,and hunt endangeredspecies

Poor people hunt “bushmeat”—driving evengreat apes to extinction


Wealth also impacts the environment

• Affluent societies haveenormous resourceconsumption– With severe, far-

reaching environmentalimpacts

– Ecological footprintsare huge

One American has asmuch environmental

impact as 3.5 Chinese or9 Indians or 13 Afghans


We must reduce population growth andconsumption

Our globalecological footprintis 50% more than theEarth can support

• For a high standard of living and quality of life for all,developing nations must slow their population growth– Their consumption

is also increasing• Developed nations

must slow theirconsumption


Conclusion

• The human population is larger than it has ever been• 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 avoiddestroying natural systems

Chapter 6: Human Population Central Case Study: China’s ... · PDF file06.10.2012 · © 2012 Pearson Education, Inc. Chapter 6: Human Population •Human population...

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