Transcript Chapter 13: Human Population

Chapter 13: Human Population
13.1 History of Human Population
13.2 Growth and Changing Needs
13.3 Challenges of Overpopulation
THOMAS MALTHUS
• 230 years ago (1798)
Thomas Malthus
published An Essay on
the Principle of
Population.
• Stated the human
population grows
geometrically
(2,4,8,16,32,64…)
while the resources to
support it grow
arithmetically
(1,2,3,4,5,6…).
Thomas Malthus
• Under these conditions
the population must
inevitably outgrow the
supply of food that is
available to fulfill its
needs.
• Predicted that
population growth
would destroy the land,
cause famine, disease
and war in England and
eventually all Europe.
Malthus’ Population Theory
• Malthus presented his
theory in response to the
“frontier ethic” that said we
controlled our environment
and owned everything in it.
• Improvements in agriculture
and the industrial revolution
prevented Malthus’ theory
from happening. But his
ideas are still applicable
today.
HUMAN POPULATION GROWTH
Since 1960, several factors have dramatically
reduced infant and child mortality throughout the
world:
•use of DDT to eliminate mosquito-borne malaria
• immunization against cholera, diphtheria, polio,
smallpox and other diseases
•discovery of antibiotics
Population Growth
• The "Green
Revolution”
increased food
output:
• development of
disease-resistant
rice, wheat and
corn
• use of fertilizers
and more effective
farming methods.
• These changes have
produced a
dramatic increase in
human population
growth rates.
Growth and Changing Needs
Growth rate =
birth rate - death rate
(per 1000 people)
Doubling time =
is the time it takes at the
present growth rate for
the population to double
Demography =
the science of changing
vital statistics in a human
population.
In the next 2.5 years, the equivalent of the current U.S.
population will be added to the planet.
In this decade one billion people (the population of China)
will be added.
U.S. National Academy of Sciences and British Royal Society
state that population is growing at a rate that will lead to
doubling by 2050.
http:/www.poodwaddle.com/worldclock.swf
POPULATION FACTS:
The Earth's population reached 6
billion in September of1999.
Human population was only 2 billion in
1930.
Every second, three people are added
to the world.
Every day a quarter of a million people
are added to the world.
 Every year, about 87 million people
are added to the world
CARRYING CAPACITY OF THE EARTH
The earth cannot continue to support a massive population
growth indefinitely.
Ecologists have often made use of the concept of carrying
capacity for all ecosystems
Measures the pressures that rapidly increasing populations put
on their environments.
Carrying capacity is simply the largest number of any given
species that a habitat can support indefinitely.
Global Carrying Capacity
Humans have:
• Changed/harmed 49-50% of the
Earth’s surface
• Increased CO2 levels by 30%
• Contaminated 50% of
accessible fresh water
• Replaced 20% of native plants
and animals on islands
• Caused the extinction of
hundreds of plant and animals
species
Human Effects on Earth
Humans cause habitat destruction and climate
change. In 20 minutes, we will destroy
1,200 acres of forest and emit 180,000 tons
of carbon dioxide into the atmosphere
worldwide. Less forest cover means fewer
acres of habitat for species and more
climate-changing carbon in the atmosphere.
As climate, landscapes, and oceans change,
species must move or adapt. Those that
can’t simply die out.
THE EFFECTS OF HUMAN ACTIVITIES
Fisheries: 20% increase in fish catch before the alarming decline in
Atlantic Cod and other major fisheries.
Nine of the seventeen major fishing areas of the world are in serious
decline, and all of them have either reached or exceeded their
limits.
Cropland. Between 1980 and 1990, cropland area worldwide
expanded by 2%.
It expanded quickly, given that the areas already taken are the ones
that are easiest to cultivate
Land is being rapidly lost to various kinds of development.
Rangeland and Pasture. Similar calculations show a decline of 22%
(and about 20% of this area is declining in productivity because of
overgrazing).
Forests. Due to a combination of deforestation and population
growth, forest area is decreasing by 30%.
UNCONTROLLED POPULATION GROWTH
Increase in population population leads to:
•increased habitat loss
•pollution problems (both local and global)
•high energy use
Most of the 3.6 billion people added to the world between
now and 2030 will be born in the developing nations, where
the overall growth rate is 2.1% per year.
The top 3 fastest growing continents are Africa, South
America and Asia:
•Kenya, fastest growing, doubling time of 20 years
•Latin America will double in 30 years
•Asia will double in size in 36 years
Many regions are already exceeding their carrying capacity;
(cannot produce enough food to support their populations).
Equatorial Africa is undergoing very rapid desertification and is
unable to support the population presently living there.
Sub-Saharan Africa has the highest birth rate, the highest rate
of population increase and the lowest use of contraceptives of
any major region in the world.
Average annual population increase in sub-Saharan Africa is 3
percent, ranging from 2.5 percent to 3.8 percent.
Food supply increases by only 1%.
12 countries of the region, women average more than seven
children per family.
Population of sub-Saharan Africa will double by 2016.
GROWTH RATE
Mexico City
doubled its population between 1960 and 1970
doubled population again between 1970 and 1980
Honduras, Kenya, Iran and Guatemala
double population size in less than 30 years
OTHER FACTORS THAT AFFECT POPULATION SIZE
LOCALIZED POPULATION
Emigration (leaving a geographic area)
Immigration (entering an new geographic area)
DEMOGRAPHY
Various factors affect the population and resource use
in any geographic area.
Breakdown includes GENDER: Male / Female
AGE: Under 15, 16-44, 45-60, Over 65
DEMOGRAPHIC TRANSITION IN SWEDEN
Before the transition, both birth and death rates are high, and the growth rate is zero or
close to it.
In the transitional phase, the birth rate remains
high while the death rate declines due to better
public health measures (e.g. immunization) and
expanded food methods. Population growth is a
result of the difference between death rate
and birth rate (ignoring immigration and
emigration for now), so the decreased death rate
leads to a high growth rate.
Birth rate declines due to better education,
better family planning, more career options
for women, and reduced infant mortality
which reduces the desire for large families.
The growth rate declines, eventually to zero.
Changing Needs
• The more people – the
greater their needs
• Changes in
technology, lifestyles,
standards of living can
affect the needs of a
population
• Industrial societies use
more energy than
underdeveloped
nations
• The least developed
nations are expected to
have the largest
population growth
Challenges of Overpopulation
Negative Effects:
• Less resources
(minerals, food, fuel)
• Less available land
• More disease
• More damage to the
environment
(magnifying pollution)
13.3 Challenges of Overpopulation
U.N. Conference on Population in Cairo in 1994
 179 nations endorsed a new "Programme of Action"
 World governments provide universal access to reproductive health
care by 2015 as a global human rights imperative.
 Focus on both population control and identifying the social problems
that contribute to population growth and poverty.
Q: Has the UN “Programme of Action” been successful?
Justify your answer with 5 scientific facts.
Governmental Controls on Population Growth
 China limits the number of children a couple can have to ONE CHILD
 Incentives to ONE CHILD couples include
better housing
preferential treatment in education
longer vacations
monetary grants
extra month’s pay
additional maternity leave
Q: What social and economic problems are caused by a ONE CHILD
policy? Would this policy work in the United States?
Justify your answer with facts.