Chapter 8 Topics:  Human population growth  Viewpoints on growth  Impacts of growth  Demography  Demographic transition  Controlling growth – social and economic factors  The HIV/AIDS epidemic  Population and sustainable development

China’s one-child policy  In 1970, 790 million people faced starvation  Instituted a one-child policy  Growth rate plummeted  Policy is now less strict  Program had unintended consequences:  Killing of female infants  “Little Emperors”

7 billion and still growing  Annual population growth = 80 + million (1.2%)  Took 200,000 + years to reach 1 billion (1800)  Took130 years to reach 2 billion (1930)  Added the 7 th billion in 12 years (2011)  Continues to rise, particularly in developing nations

Growth rates vary geographically

Growth rates in perspective  At today’s 1.2% global growth rate, the population will double in 58 years (70/1.2 = 58) [rule of 70]  Technology, sanitation, medication, and increased food production led to population growth  Growth is sometimes seen as good as it provides support for the elderly and a larger labor pool  Growth has also been seen in apocalyptic terms, as the cause of wide-spread starvation and conflict (Malthus, 1798; Ehrlich, 1968)

Complex and nuanced  Some would argue that growth is not a problem  New technologies (the Industrial Revolution, the Green Revolution) have held off famine so far  New resources have replaced threatened or depleted ones  But there really are limits and consequences  Some resources are not replaceable or inter- changeable  Unchecked growth will affect the quality of life

Falling rates, growing population  Declining growth rates do not mean declining populations  Populations continue to grow, but at a slower rate

A fear of falling population  Policymakers have believed that population growth increases economic, political, and military strength  Today, high growth correlates with poverty, not wealth  Falling birth rates do lead to an aging population  Many elderly needing services  Fewer young workers to pay the taxes needed to fund them  If immigration is used to maintain a country’s population, a loss of cultural identity may occur  Some nations with low birth rates now offer incentives for more children

Population growth concept map

The IPATS model  The IPATS 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

Demography  Demography: using population ecology to study the change in human populations  All population principles apply to humans  Environmental factors limit population growth  Humans raise the environment’s carrying capacity through technology  The Agricultural Revolution – 10,000 yrs ago  The Industrial Revolution – 200 yrs ago  How many humans can the world sustain?  1–33 billion: prosperity to abject poverty  Population growth can’t continue forever

Population size and density  The UN predicts 9 billion by 2050  Increased density increases impacts to the environment  Highest density: tropical, subtropical, temperate biomes  Lowest density: away from water

Population distribution  Humans are unevenly distributed around the globe  Unpopulated areas tend to be environmentally sensitive (e.g., deserts, arid grasslands)

Age structure  Wide base (many young):  High reproduction  Rapid population grow  Even age distribution:  Remains stable  Births = deaths

Aging populations  In 1970, the median age in China was 20  By 2050, it will be 45  By 2050, over 300 million will be over 65  Fewer people working to support social programs  The elderly can remain productive

Sex ratios  Human sex ratios at birth slightly favor males  For every 100 females born, 106 males are born  The impacts of China’s one-child policy:  120 boys were reported for 100 girls  Cultural gender preference resulted in increased termination of females  The undesirable social consequences?  Many single Chinese men  Teenage girls preyed upon by human traffickers

Rates of population change  Overall population change (+, −, 0) depends on rates of birth, death, and migration  Natural rate of population change = due to birth and death rates alone  Immigration and emigration have significant effects on human populations  War, civil strife, and environmental degradation cause 25 million people to migrate annually  Causes environmental problems because there are no incentives to conserve resources

Fertility rates  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)  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  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  Increases with reduced rates of infant mortality  Urbanization, industrialization, and personal wealth reduce infant mortality rates

A possible explanation  Demographic transition = a model of economic and cultural change and population growth  A stable pre-industrial state of high birth rates and high death rates changes to a stable post-industrial state of low birth rates and low death rates  The temporal lag between the initial decline in death rates and a subsequent decline in birth rates causes a period of rapid population growth

The Demographic Transition Model

Is it real?  The Demographic Transition has occurred in Europe, the U.S., Canada, Japan, and many other nations over the past 200–300 years  But it may or may not apply to the remaining developing nations  The transition could fail in cultures that:  Place greater value on childbirth  Grant women fewer economical and social freedoms

Controlling birth rates  The greatest single factor slowing population growth  Birth control = controlling the number of children born (reducing the frequency of pregnancy)  Family planning = affects the number and spacing of children  Clinics offer advice, information, and contraceptives  Hindered by religious and cultural influences  Rates range from 10% (Africa) to 90% (China)

Empowering women  Educating women reduces fertility rates, delays childbirth, and gives them a voice in reproductive decisions  Women with little power have unintended pregnancies  Two-thirds of the world’s illiterate are women  Access to family planning is important

Gender equity  We are a long way from gender equality  Over 60% of the world’s poor are women  Violence against women remains shockingly common  Many men resist women’s decision making  The gap is obvious at high levels of government  The U.S. lags behind the world in proportion of women representatives in government

Family planning works  Funding and policies that encourage family planning lower population growth rates  Thailand’s educational-based approach reduced its growth rate from 2.3% to 0.6%

Poverty and population  A positive feedback cycle – 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 and the environment  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)

Wealth and the environment  Population problems are not restricted to poor countries  Affluent societies have enormous resource consumption and waste production  Use resources from other areas, as well as their own  Ecological footprints are huge  The richest 20% use 86% of the world’s resources  One American has as much environmental impact as 4.5 Chinese or 10 Indians or 19 Afghans

HIV/AIDS in Africa  AIDS epidemic having greatest impact on global population since the Black Death (1300s)  Of 33 million infected, two-thirds live in sub- Saharan Africa  Low rates of contraceptive use spread the disease

Demographic fatigue  AIDS and other population issues undermine the economic, social, and political functioning of poor nations  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  Addressing population issues is necessary for achieving sustainable development goals

Take-aways  The human population is larger than at any other time  Growth rates decreasing but populations 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