The Causes and Risks of
Population Growth
Crispin Pierce, Ph.D.
(crispo@u.washington.edu)
“Unlike plagues of the dark ages or
contemporary diseases we do not
understand, the modern plague of
overpopulation is soluble by means we have
discovered and with resources we possess.
What is lacking is not sufficient knowledge
of the solution but universal consciousness
of the gravity of the problem and education
of the billions who are its victim.”
Martin Luther King, Jr., 1929-1968
“The list of environmental problems aggravated by growing
populations includes deforestation and desertification, loss of
topsoil, poisoning of drinking water and pollution of oceans,
shrinking wetlands, shortage of fuels such as firewood,
exhaustion of oil reserves and of various mineral resources,
siltation in rivers and estuaries, dropping water tables, erosion
of the ozone layer, loss of species and wilderness areas, global
warming, rising sea levels, nuclear waste, air pollution, and
acid rain.”
Rebecca Clay, Environmental Health Perspectives, vol. 103
(1995).
“Currently the U.S. has no policy on population — even though
both the Rockefeller Commission in 1972 and the President’s
Commission on Sustainable Development in 1995 recommended
that the U.S. adopt policies to stabilize the U.S.’s population.”
COPHP Student, 2003
Overpopulation exists if the
activities of the current population
are depleting the capacity of the
environment to provide for future
populations.
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How fast is population size increasing?
What are the causes of increase?
What are the effects of increase?
Population increase myths.
Which tools are effective at slowing
population increase?
• What can I do?
How fast is population size
increasing?
• Currently at 274 million, the U.S.
population is growing by about 2.5 million
people each year, making the United States
one of the world's fastest-growing
industrialized nation. The U.S. fertility is
currently at 2.0, up from 1.8 in 1988.
• Immigration adds at least another 800,000
people annually to our nation's population.
What are the causes
of increase?
• Improved medicine, sanitation, and nutrition
have produced a major decline in death rates,
particularly in the last century. For example, life
expectancy in Egypt increased by twenty years
between 1940 and 1960.
• Birth rates have declined much more slowly.
• Households in rural areas of developing
countries often have little or no
assurance that they will receive an
income when old: there is no social
security system, no employer
subsidized funds, no medical insurance
or life insurance. Children may be
viewed as an asset which will generate
income when the parents are old.
• In many countries, the degraded status of
women is another contributing factor to
high birthrates. Women are often denied
opportunities for education, employment,
land ownership, and governmental service.
As a result, they have few alternatives to
their childbearing roles.
• Developing areas such as Africa, Latin
America and parts of Asia are still primarily
agrarian; therefore, incentives for having
larger families still exist.
• Following adoption of basic technology
that improved living conditions, death rates
plunged dramatically. As a result, these
populations are growing rapidly.
Why do households have
more children than may be
best for society?
• People may not recognize the implications
of falling death rates for their fertility
decisions.
• Family size choices may have
consequences for other families that are not
considered. For example, publicly funded
education, child care, tax deductions, and
child welfare programs. Similarly,
congestion costs of overpopulation and
• For large extended families that are
typical in rural areas, there are often
perceived decreased costs associated
with having children. For example, the
private costs of a child to one mother
may be lower if she expects her sister to
help in child rearing.
• Societies and religions have developed
social norms to encourage child rearing
(e.g. celebration of childbirth), and to
discourage birth control.
What are the
effects of
increase?
• As human population increases, the
diversity and number of plants and
animals decreases. We lose one or
more entire species of animal or plant
life every 20 minutes – 27,000 species a
year. This is a rate and scale of
extinction greater than any in the last 65
million years.
• “Six million acres of prime farmland – an
area the size of Vermont – were lost in
the United States alone between 1982
and 1992. Four of those six million
acres were lost to urban and suburban
expansion. The other 2 million acres
were lost through erosion caused by
deforestation, unsustainable farming
practices, and animal over-grazing.”
• Global carbon dioxide emissions have
quadrupled since 1950, largely from
deforestation and the burning of fossil fuels.
This “greenhouse gas” addition causes
global warming and disruption in weather
patterns.
– Five storms over the span of five years have
cost the insurance industry in the United States
$25.7 billion.
– Increased spread of malaria, cholera, typhoid
fever, and dengue fever worldwide are
expected.
Population increase myths.
• “Per capita food production is
increasing, so the Earth must be able
to sustain population growth.”
• Per capita meat production has
increased:
• Per capita production of grains has
decreased since 1984:
• It takes 23 times more water, and ten times
more energy to produce one ton of beef
than it does to produce one ton of grain.
• Current unsustainable agricultural practices
have led to widespread cropland losses and
extensive water pollution from pesticides
and fertilizers (e.g., the Mississipi River and
the death zone in the Gulf of Mexico).
• “Technology and market forces will provide
solutions to problems associated with
population increase.”
– “As populations grow, especially in rural
areas, increased scarcity of land (and other
resources) may drive people to innovate
and adopt new methods and technologies
that use them more efficiently. It is often
argued, for example, that the agricultural
revolution in the UK and other European
countries after 1650 was driven by
population growth.”
• Market systems subsidize industries such as
logging, mining and grazing without considering
environmental costs. Degradation of commonly
held resources such as groundwater levels or
atmospheric and ocean quality is not included.
Nor do markets consider Earth's "services," such
as regulation of climate, detoxification of
pollutants or provision of pollinators, much less
questions of human equity and social justice.
• “The entire population of the world could fit
into an area the size of Texas.”
• Dividing the world's 6 billion humans into
Texas's 261,914 square miles, each person
would have 0.028 acres of land. However
this land in Texas, (or even all the land in
North America for that matter), would not
be able to sustain these people. A minimum
of 0.17 acres of arable land is needed to
sustain a person on a largely vegetarian diet
without the intense use of fertilizers and
pest controls.
• The tiny amount of land per person in the Texas
scenario could not accommodate the intense
demands we place on our lands (particularly in
developed countries): roads, businesses, grazing
lands, lawns, airports, etc.
Group Projects
• Exponential Growth Questions
• Questions of Freedom
• The Economic Costs of Population Growth
Exponential Growth Questions
• Would you rather receive
$10,000, or the amount after
thirty days, where you receive
one cent on day one, two cents
on day two, four cents on day
three, etc.?
• If the current rate of world population
increase is 1.31%, how many additional
people will inhabit the planet in one year?
• Which costs would you include in the price
of gasoline to adequately reflect the natural
resource costs of petroleum exploration,
development, and use?
Questions of Freedom
• Which freedoms in American society
decrease with increased numbers of people?
• Are there freedoms that are increased with
increased population density?
• Who should decide on losses of freedom vs.
population stabilization?
The Economic Costs of
Population Growth
• There are three major areas of U.S. taxation:
property taxes, income taxes, and sales
taxes. Which of these taxes is
disproportionally spent (but not collected)
on families with large numbers of children?
Which of these taxes is disproportionally
lower for families with large numbers of
children?
• Should municipal entities, such as schools,
city boundaries, and water and sewage
systems be designed and built for a target
population size? Should additional residents
(born children and/or migrants) have to live
elsewhere once a city has reached its
maximum size?
Which tools are effective at
slowing population
increase?
• Improve the health of women and children.
– Improved family planning supports women in
choosing to delay motherhood, prevent
unwanted pregnancies, and avoid STDs
(including AIDS) and dangerous abortions.
Improved family planning could reduce child
and infant mortality by 25%, preventing three
million deaths per year.
• Guarantee access to family planning
resources.
• Eradicate violence against women.
– Abused women are afraid to use family
planning services for fear of reprisal from their
husbands.
• Educate and involve men in family planning
and child care.
• Create gender equity.
– Insist on women’s rights to own property, to get
an education, to earn income, and to participate
in government.
• Actively conserve cropland, freshwater,
energy, and other environmental resources.
What can I do?
• Plan the size of my family. Consider having
two or fewer children, and/or adoption.
• Support domestic and international family
planning programs.
• Become involved in programs supporting
equal rights, and educational and job
opportunities for women worldwide.
• Conserve energy and natural resources (one U.S.
citizen consumes about 30 times as much as a
citizen of India).
• Encourage reduction of western patterns of
consumption.
– The richest fifth of the world consumes 86% of all
goods and services and produces 53% of all carbon
dioxide emissions, while the poorest fifth consumes
1.3% of goods and services and accounts for just 3%
of C02 output.
References
Zero Population Growth
The Union of Concerned Scientists
Cornell University
PregnantPause