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Study Guide for Environment: The Science Behind the Stories. These notes are for classroom use only.
.
Chapter 7 Notes
China's One-Child Policy
Between 1950 and 2000, China's population grew from 540 million to over 1 billion people.
The average Chinese woman gave birth to 5.8 children.
This rapid population growth, along with industrialization and
agricultural development, caused massive environmental damage.
\
The government decided to enact a population control policy of one child per family, accomplished through such
measures as delayed marriage, contraceptives, and abortion.
Social incentives (e.g., better schools, housing, and medical care) and disincentives (e.g., social scorn, employment
discrimination, and fines) were also enacted.
Although successful in bringing down population growth, China's policy
has produced criticism, along with the practice of killing some female infants and an unbalanced sex ratio.
Human Population Growth: Baby Six Billion and Beyond In 1999, the six-billionth human being was born on
Earth.
The human population is growing nearly as fast as ever
We add 79 million people per year to Earth's human population.
We added 1 billion (from 5 billion to 6 billion) in only 12 years, whereas it took until 1800 to reach the first billion.
For most of the 20th century, human population growth has occurred at a greater than exponential rate, so that the
percentage increase actually rose each year to peak at 2.1 %.
At a growth rate of 2.1 %, the population doubles every 33 years (70/2.1), so that China's population, if no controls had
been instituted, would now be over 2 billion people.
Is population growth really a "problem"?
Population growth is mostly caused by decreasing death rates that result from better sanitation, health care, and food
production.
Some economists and others believe population growth is a good thing as long as resources can be found to replace
depleted ones.
Environmentalists believe that not all resources, such as biodiversity and land, can be replaced once depleted.
Population becomes a problem when it stresses the environment, resources, or social systems so that the present quality of
life declines. Many governments want population growth because they think it
increases a nation's economic, political, and military strength, so they pro- vide incentives for couples to have more
children.
Population is one of several major factors that affect the environment
The IPAT model shows how the human impact (I) on the environment results from population (P), affluence (A), and
technology (T).
The sensitivity (S) of the environment to human pressures influences the IPAT model (I = P X A X T X $).
When any of. the three factors increases, it magnifies the environmental impact.
Affluence is defined as per-capita resource consumption that goes along with increased wealth.
Technology is used to exploit resources, such as fossil fuels, fisheries, and forests.
Factors such as education and laws also affect how population, affluence, and technology impact the environment.
Despite increased affluence and population, the human population has
not crashed because humans have developed technology (T) to decrease the strain on resources and feed more humans.
With a high P, if A increases, the environmental destruction can be massive; China's large population is driving rapid
development so that important agricultural areas are eroding, aquifers are being depleted, and rivers are drying up.
The principles of population ecology apply to humans
Humans are subject to the same principles of population ecology as
are other organisms and have a carrying capacity set by environmental limitations.
However, through technology, humans have pushed back natural limits and raised the carrying capacity.
Although the human population continues to grow, according to population ecology it cannot continue to grow forever.
Demography is the science of human population
Demography applies the principles of population ecology to the study of the change in human populations.
Demographers study population size, density, distribution, age structure, and sex ratio, and rates of births, deaths, and
migration.
Demographers use information to predict population dynamics and human impacts on the environment.
Population size: Countries around the world vary in their numbers of in- habitants, from China's 1 billion to countries
with only thousands.
Population density and distribution: Humans are distributed in a clumped
fashion around the world, with the highest densities in temperate and
tropical environments, and the lowest densities in extreme climate biomes. Because humans are unequally distributed,
certain areas of the environment (such as major rivers and cities) are more heavily impacted than others.
Sensitive environmental areas such as deserts and grasslands cannot sup- port many people (such areas have a large S
value in the IPAT model).
Age structure: Demographers use the age structure of a population to try to predict future population dynamics.
Reducing the number of children born results in fewer future adults that will have children.
With fewer children being born, there will be a reduced proportion of dependents, fewer young adults (which may mean
less crime), and the
elderly will remain productive members of society as they volunteer their services to children and grandchildren.
As populations in some countries age, social challenges will arise as the I elderly require more care and financial
assistance from fewer working-age citizens.
Sex ratio: Although most populations have an equal sex ratio, a population with more females will grow, because there
are more potential mothers that can have children.
A skewed sex ratio may lower population growth if there are not enough females to have offspring.
Population growth depends on rates of birth, death, immigration, and emigration
Birth rates, death rates, immigration, and emigration determine whether the human population grows, shrinks, or remains
the same.
The human population has grown because of decreased death rates.
Twenty-five million refugees each year flee countries because of poor environmental conditions, but they often cause
environmental problems in the receiving region, because they have no cultural or economic attachment to the land to
conserve it.
Some countries are experiencing decreased birth rates for several reasons.
A population's total fertility rate can shape population growth rate
The total fertility rate (TFR) is the average number of children born per female member of a population during her
lifetime.
The TFR can help demographers predict a population's potential for growth.
Replacement fertility is the TFR that keeps the population stable, and equals 2.1.
The TFR has declined because: (1) lower infant mortality rates cause couples to have fewer children, because more
survive; (2) urbanization means that children are no longer required to work on a farm and actually cost the parents more
economically; (3) with increased governmental social services, fewer children are required to support parents; and (4)
with more working women, less emphasis is placed on having children.
The natural rate of population change is change due only to births and deaths, not to migration.
Women's empowerment and family planning greatly affect population growth rates
, Drops
in TFR have been dramatic in countries where women have access
to contraceptives and education, including family-planning education.
In countries such as China, Western Europe, the United States and Brazil, more than 70% of married women use
contraceptives.
In other countries (many in Africa), fewer than 10% of married women use contraceptives.
In societies where women have little power, many pregnancies are unintended.
The United States has refused to fund worldwide family-planning efforts; in fact, in 2001, President George W. Bush's
first act as president was to cancel family-planning funds.
Some nations have experienced a change called the demographic transition
As a result of better nutrition, sanitation, and health care, the life expectancy for humans has increased from 46 to 66
years.
The global crude death rate has also dropped from 20 deaths per 1,000 people to fewer than 10 deaths per 1.,000.
Life expectancy is the average number of years that individuals in a particular age group are likely to continue to live.
Increased life expectancy is due to fewer infant deaths, and occurs in urbanized, industrialized, wealthier nations.
The demographic transition is a theoretical model that explains why deaths and births are decreasing.
According to the demographic transition, industrialization causes birth and death rates to fall naturally because there is
less need for larger families.
The pre-industrial stage: This first stage, called the pre-industrial stage, is characterized by high birth and death rates.
Disease, little medical care, and scarce food drive up death rates, and birth rates are high because people have lots of
children so that at least some will survive
Populations do not grow, because the high death rates balance the high birth rates.
Industrialization
and falling death rates: This second stage, known as the transitional stage, has lower death rates because
of more food
and better medical care.
However, because birth rates are still high, the population grows rapidly.
The
industrial
the home,
and stage and falling birth rates: During the industrial stage, industrialization provides women with jobs outside
children become less valuable (in economic terms) because they are no
longer
needed
to help
children,
resulting
in families get food. When couples have access to contraceptives, they may choose to have fewer
falling birth rates.
The
post-industrial stage: In this fourth stage, both birth and death rates are low, resulting in a stable, even declining,
industrialized
population.
Is the demographic transition a universal process?
Although
the demographic
transition has occurred in Europe, Japan, and the United States, some social scientists doubt
that it applies
to
today's developing countries.
The demographic
transition may fail in countries whose culture places great value on children, or that don't have enough
natural
resources to
develop. ) For the entire world to enjoy the same quality of life as in the United
States, we would need the natural resources of three more planet Earths.
Populationare
policies
and family-planning
programs are working around the globe Funding and policies that encourage family
planning
effective
in
lowering
(1960s) topopulation growth rates, even in the least industrialized countries. Thailand's growth rate has been cut from 2.3%
0.8%
in 2002 by using an education-based approach to family planning and access to contraceptives.
Countries
strong programs of population reduction targets, incentives, education, contraception, and reproductive
health carewith
show
marked decreases in fertility.
The
of thedriving
rulingforce behind implementing family-planning policies usually is not public demand, but the political ideology
party.
Currently,
mainstream population policy has turned away from encouraging contraception and lowering population
and towardthe
better
education and health care and less disease and poverty.
Women still need more empowerment
Before the human population will stabilize, women need to be granted equal power with men in society.
We are far from reaching equality for women; 60% of those living in
poverty are women, and traditionally men still control women in deciding how many children to have.
Gender equality not only results in fewer, healthier children, but also in more efficient resource use such as of water and
fuel wood.
The United States lags behind many developed nations in the proportion of women in positions of power in government.
Poverty is strongly correlated with population growth
Poorer nations tend to have higher fertility and growth rates resulting
from higher birth and infant mortality rates and lower contraceptive use. Over 98% of the population growth will occur in
the poorest countries that are already least able to provide for their current populations.
Poverty also results in environmental degradation, from over-farming agricultural regions to hunting large mammals to
extinction.
The consumption that comes with affluence creates a large
environmental impact
Wealthy countries can have massive, negative environmental impacts because of their enormous levels of resource
consumption.
Individuals from affluent societies leave a larger "ecological footprint"
The A (affluent) portion of the I = PAT equation involves each individual's behavior and resource consumption.
The ecological footprint is the environmental impact of an individual or population, and represents the amount of land and
water needed to pro- vide the raw materials the person consumes and disposes of.
Some scientists feel that resource consumption poses a larger environmental problem than population, because there is no theoretical limit to what a person can consume.
The wealth gap and population growth contribute to violent conflict
The large gap between rich and poor societies causes social, as well as environmental, stresses.
The richest 20% of the world's people have 82 times the income of the poorest 20%, as well as use 86% of the world's
resources.
Because only 14% of the resources are available to 80% of the population, there is great potential for armed conflict.
HIV/AIDS is a major factor affecting populations in some parts of the world In countries with high incidences of HIV / AIDS,
mortality is increasing, not decreasing.
African nations are hardest hit: 20% of the population in southern African countries has HIV/AIDS.
The infant mortality rates in some African countries are elevated, and life expectancy is only 44 years, equivalent to the
life expectancy of the 1950s. By 2010, there will be 40 million orphans in Africa.
Severe demographic changes have social, political, and economic repercussions
In addition to the demographic effects of AIDS, the disease is having social, economic, and political consequences.
With younger, more productive people dying, countries are not moving toward modern technologies.
With fewer workers, income drops, food production declines, and medical expenses and debt increase.
Demographically fatigued governments must not only contend with problems like AIDS, but are also finding it hard to
educate and find jobs for their citizens.
Unless countries can find ways to solve their population problems, economic and social problems will get worse,
negatively affecting both humans and the nonhuman environment.