Transcript Changes in Population Size

P 185
Chapter 7
The Human Population
China’s Population
• Human population size, affluence, and resource
consumption all have interrelated impacts on the
environment.
China:
• 20% of world population (1.3 billion).
• Rapid economic development.
• Already largest producer of CO , SO .
• Soon to be world’s largest economy.
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US is current largest economy (318.9 million
people (2014) )
Population control
• Since 1970’s -2015 China had a 1 child policy.
• Financial rewards for sticking to one, sanctions
for 3 or more (10% salary reduction).
• Numerous tools to meet standards: Sterilization,
abortion, designation of certain pregnancies as
illegal (female infanticide and under reporting).
• Decades of highest birth rate now at 1.6 births per
woman.
• Base so large it will take years to level off and
decline.
China’s population
grows cars too!
• 1985-2002 China population grows 30%
• Vehicles grew by 500%
• Today 25 million private cars on road
(from 3 million).
• Second largest consumer of petroleum.
• 2006- 16 of 20 most polluted cities were
in China. Now …
Scientists Disagree on Earth’s
Carrying Capacity
Every 5 days the
global population
increase by 1
million.
Changed about
400 years ago
when agriculture,
sanitation,
vaccines, etc.
began/improved.
Current human
population 7.4
billion.
Figure
7.1
Scientists Disagree on Earth’s Carrying
Capacity
•The following graphs show
theoretical models of food
supply and population size.
•One of the first notions that
human population could
exceed Earth’s Carrying
Capacity (proposed by
Thomas Malthus)
•Actual because of intellect
Feeding Nine Billion Video 1: Introducing Solutions
to the Global Food Crisis
by Dr. Evan Fraser
https://www.youtube.com/watch?v=raSHAqV8K9c
MANY FACTORS DRIVE GROWTH
Factors that Drive Human Population
Growth
•
Demography- the study of human
populations and population trends.
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Changes in Population Size
Fertility
Life Expectancy
Age Structure
Migration
Changes in Population Size
• Immigration- the movement of people into a
country
• Emigration- the movement of people out of a
country.
• Net migration rate- the difference between
immigration and emigration in a give year per
1,000 people in the country.
Changes in Population Size
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Crude birth rate (CBR)= the number of births per 1,000 individuals per year.
Crude death rate (CDR)= the number of deaths per 1,000 individuals per
year.
•
Global population growth rate =
(CBR- CDR)
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•
10
National population growth rate =
(CBR+ immigration) - (CDR + emigration)
10
Doubling time (in years)70_____
growth rate
Fertility
• Total fertility rate- an estimate of the average
number of children that each woman in a
population will bear.
• Replacement level fertility- the total fertility
rate required to offset the average number of
deaths in a population and for the current
population size to remain stable.
By 2050: 8.1-9.6 Billion
Expected to stabilize at 6.8-10.5
billion by 2100.
TFR
• Total Fertility Rate: An estimate of the
average number of children that each
woman in a population will bear in her
childbearing years.
• Replacement Level Fertility: The TFR
required to offset the average number of
deaths in a population so that the
current population size stays stable.
Fertility
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Developed countries- countries with relatively
high levels of industrialization and income.
Developing countries- countries with relatively
low levels of industrialization and income of less
that $3 per person per day.
Life Expectancy
•
Life expectancy- the average number of years that
an infant born in a particular year in a particular
country can be expected to live, given the current
average life span and death rate of that country.
Life Expectancy
•
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Infant mortality rate- the number of deaths of
children under 1 year of age per 1,000 live births.
Child mortality rate- the number of deaths of
children under age 5 per 1,000 live births.
In 2009 the global infant
mortality rate was 46. US
infant mortality rate was
6.6.
Availability of prenatal
care!
Even when things
look good…
• Even when the overall numbers seem to
indicate a high level of health care throughout
the country, the reality may be strikingly
different for portions of the population.
• Environmental Justice (more in chapter 20).
• Related to socioeconomic status and varying
access to adequate nutrition and health care.
•
Age Structure
Age structure diagrams (population pyramids)visual representations of age structure within a
country for males and females.
DEMOGRAPHIC TRANSITION
The Demographic Transition
•
The theory of the demographic transition is the theory
that as a country moves from a subsistence economy to
industrialization and increased affluence, it undergoes a
predictable shift in population growth.
Demographic Transition is not
a complete picture though, it is
a prediction: Nicaragua
displays the birth and death
rates of phase 4 even though
its industrialization is that of
phase 1 (developing).
The Stages of the Demographic Transition
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Phase 1: Slow population growth because there are high
birth rates and high death rates which offset each other.
Phase 2: Rapid population growth because birth rates
remain high but death rates decline due to better sanitation,
clean drinking water, increased access to food and goods,
and access to health care.
Phase 3: Stable population growth as the economy and
educational system improves and people have fewer
children.
Phase 4: Declining population growth because the relatively
high level of affluence and economic develop encourage
women to delay having children.
Family Planning
•
Family planning- the regulation of the number or
spacing of offspring through the use of birth
control.
As the education of women
increase and women earn
more money of their own,
fertility goes down.
The 12 Most Populous Countries in the
World
9 of the 12 most
populous countries
are developing.
Of Earth’s 6.8
Billion people, 5.6
billion live in
developing
countries. 1.3
billion live in
developed nations:
this 20% of the
population uses
over 50% of the
resources. (2-10
times the
environmental
impact.
The relationship between economic development
and population growth rate for developing
nations.
Population growth in
developed nations has
mostly ceased, while
population growth in
developing nations is
slowing, but expected to
continue beyond 2050.
Ecological Footprints
•
Affluence - having a lot of wealth such as
money, goods, or property.
Average footprint
for the 50 poorest
countries is 1ha
(2.5 acres).
U.S. = 9ha (22
acres)
China’s rapid
development is
likely to cause
their Footprint to
exceed US in 10
years.
The IPAT Equation
• To estimate the impact of human lifestyles on
Earth we can use the IPAT equation:
• Impact= Population X Affluence X Technology
I=PAT (advanced)
• Impact= Population X Affluence X Technology
Stewardship
• Some of the most affluent countries have
access to some of the best technologies that
allow them to buy products that have less of an
environmental impact. Technology can either
degrade the environment or create solutions to
minimize our impact.
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The Impact of Affluence
Gross domestic product (GDP)- the value of all
products and services produced in a year in that
country.
GDP is made up of consumer spending,
investments, government spending, and exports
minus imports.
A countries GDP often correlates with its
pollution levels.
•
As it increases further, it may reach a point
where they are able to purchase equipment to
burn fossil fuels more efficiently and cleanly.
It’s pretty amazing how ridiculously large the US economy is, and the map below helps put America’s
GDP of nearly $18 trillion in 2014 into perspective by comparing the GDP of US states to other
country’s entire national GDP.
https://www.aei.org/publication/putting-the-ridiculously-large-18-trillion-us-economy-into-perspective-by-comparing-state-gdps-to-entire-countries/
NOVA - WORLD IN
BALANCE - THE
PEOPLE PARADOX
- Discovery History
Life (documentary)
https://www.youtube.com/watch?v=gubSO
_U8MW0