Part two review
Human Population Dynamics
(10-15%)
The Human Population
China
&
India
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More than 6.3 billion people currently
* U.S. 300 + Million
Last 25 yrs population grew by 2 billion
Projected that population will be 10 billion by 2050
Increase pop → increase need for resources
* Malthus
Reproductive strategies
Factors that influence fertility
– Children in labor force – if allowed = higher birth rate
– Urbanization – people in urban areas have fewer children
– $ Cost of raising children (less in developing countries
because they often work)
– Education/employment of women –
-empowering women
– Infant mortality
– Age at time of marriage – younger = more children
(b) crude birth rate= number birth per 1000 individuals
(d) crude death rate= number death per 1000 individuals
(r) growth rate = natural increase in population expressed as
percent per years (If this number is negative, the population is shrinking.)
Equation: rate = birth – death / years
1000
Population growth rates con’t
increase population
births

immigration 
decrease population

deaths
 emigration (exit)
r = (birth - death)+ (immigration-emigration)
Immigration = migration of individuals into a population from another area or
country
Emigration = migration of individuals from a population bound for another
country
r = (birth - death)+ (immigration-emigration)
Example: population of 10,000 has
100 births (10 per 1000)
50 deaths (5 per 1000)
10 immigration (1 per 1000)
100 emigration (10 per 1000)
You try.
B
D
I
E
r=( 10/1000) – (5/1000) + (1/1000) – (10/1000)
r=(0.01-0.005) + (0.001 – 0.01)
r = 0.005 – 0.009 = -0.004 or –0.4% per year
For example, at a 10% annual growth
rate, doubling time is 70 / 10 = 7 years.
Similarly, to get the annual growth rate,
divide 70 by the doubling time. For
example, 70 / 14 years doubling time = 5,
or a 5% annual growth rate.
Growth Rate
(% per Year)
Doubling Time
in Years
0.1
700
0.5
140
1
70
2
35
3
23
4
18
5
14
6
12
7
10
10
7
If the growth rate is 1% and the population size is
10,000, how many years will it take to get to a
population of 40,000?
Population doubling:
70/rate =70/1% =70 years to double
In 70 years the population will be 20,000
1 D.T.  20,000
2 D.T.  40,000
(70 years)(2) =140 years
In 140 years, the population will be 40,000 people.
SHOW YOUR WORK!!!!!!!!!
Preindustrial
Transitional
Industrial
Postindustrial
Bottom Line= as countries develop, first their death rate drops and then their birth rate drops
Reasons for the phases:
Phase II: 

medical care
nutrition (births still high)
 technology
Phase III: 
birth control

education (of women)

lower mortality rate of infants

less child labor
Developed Countries
 Canada, U.S., Australia, Western Europe (Denmark)
Developing Countries
 Latin America, China, Africa (Kenya)
 1/5 of the world’s pop. Lives in absolute poverty, illiterate, lack clean
H2O and don’t have enough food
 80% of world’s pop. Lives in developing co. and growing.
• Special agency of the United Nations
• Receives $$ from developed co. and loans $$ to developing
co.
– Sometimes this backfires by increasing debt
• Oversees all types of issues, not just environmental issues
– Ex. electricity, roads, new modern technology
Survivorship – many women in developing countries have a
large number of children because many of the children
don’t survive childhood due to high infant mortality rate –
**which is the single most important measure of a society’s
quality of life.
– Currently replacement-level fertility (RLF) in DEVELOPED
countries is 2.1 children per couple, in DEVELOPING
countries, it is as high as 2.5 children per couple .
Total fertility rate (TFR) = estimate of avg. # of children a
woman will have during childbearing years if she bears
children at the same rate women did this year.
Now (1.6 in developed countries – down from 2.5 in 1950,
3.1 in developing – down from 6.1 in 1950)
Between 1965 – 2002, the world’s infant
mortality rate has dropped sharply.
**Major reason for fast growth of world
population is decline in death rates.
Most useful indicators of health of a country
= life expectancy and infant mortality rate.
» Infant mortality is single most important measure of a
society’s quality of life.
» US mortality rate is higher than 37 countries b/c of:
inadequate health care for poor women during
pregnancy/their babies, drug addiction among pregnant
women, high birth rate of teenagers.
Age-structure diagram
Population size
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Strategies for sustainability
Family planning = birth spacing, birth control,
Health care for pregnant women and infants;
Empowering women = education,
Women’s rights; offer incentives/penalties to
slow population growth
Thailand – cut population growth rate in half in 15 years of family planning.
US – baby-boomers, 1946-1964, now make up nearly half of adults, will create a
problem for Social security in the future
China – successful, sharp drops in fertility using VERY restrictive governmental
population control: couples strongly urged to have no more than one child,
postpone age of marriage; married couples have free access to sterilization,
contraception, abortion; married couples who pledge to have no more than one
child get incentives (extra food, money, etc.)
India – world’s first national family planning program in 1952 – disappointing b/c poor planning,
low status of women,
Cairo, Egypt, September 1994
The International Conference on Population and Development (ICPD) was held
in Cairo, Egypt, from 5 to 13 September 1994.
Delegations from 179 countries took part in negotiations to finalize a Program
of Action on population and development for the next
20 years.
Our Mission is to:
Improve the quality of life of individuals by campaigning for sexual and
reproductive health and rights through advocacy and services, especially for
poor and vulnerable people
Defend the right of all young people to enjoy their sexual lives free from illhealth, unwanted pregnancy, violence and discrimination.
Layers of the Atmosphere
Weather
Most Gasses
Composition of the troposphere
• 78% N2
• 20% O2
• Less than 2%
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H2O vapor (.01%-4%)
Argon gas (1%)
CO2 (0.04%)
Trace gases
spheric Ozone
Formation of stratospheric Ozone – molecular oxygen (O2)
reacts with UV-radiation in stratosphere, and breaks up into
O-atoms…those then react w/O2 in the atmosphere to form
O3 (ozone)
Ozone (O3)
Tropospheric ozone is BAD
•If we breath it, it causes lung damage
•It is also a greenhouse gas
Stratospheric ozone is GOOD
– It shields us from the harmful UVB rays of the sun.
– Ozone depletion is the thinning of the stratospheric
ozone shield (mostly over the South Pole, Australia
story)
– Analogy – Stratospheric O3 is like sunscreen for the earth.
UV radiation – high energy form of ionizing radiation, very
harmful to life make sure you know the difference b/t Ionizing
radiation (BAD): UV, x-rays, gamma-rays; if UV (ionizing
radiation) reaches earth surface can hurt living cells, cause
sickness and cancer)
NON-Ionizing radiation: IR, microwaves, TV/radiowaves);
• Causes of ozone depletion
– Chlorine from CFCs (mainly refrigerators/air conditioner coolants) *some also
from Halons (fire extinguishers), methyl bromide (fumigant), CCl4(carbon
tetrachloride-a common solvent) are unreactive in troposphere, rise into
stratosphere in 11-20y (by convection)
– In stratosphere, CFCs break down b/c of UV radiation, this releases Chlorine
atoms, which react with Ozone, pulls off an O to form ClO, O then pulls free
from the Cl, then two free-O’s combine to form stable O2
– Cl then goes on the destroy another ozone molecule (can last in stratosphere
destroying ozone)
Ozone thinning in Antarctica, during the winter *REMEMBER their
winter is OUR summer (June-August); ice crystals collect ClOs, but O doesn’t
break free (b/c dark, no UV radiation to split it apart) so become more stable
Cl2O2…this means that during June-Agust, ozone amount is fairly high b/c Cl
is not breaking it up…
When sunlight returns (October), sunlight (UV radiation) breaks up Cl2O2 molecules,
causing a LOT of ozone destruction at once (b/c so many free Cl atoms to react) – same
can happen in the arctic but thinning happens in the spring since it is in N.Hemisphere
• Effects of ozone depletion
– Worse sunburn, more eye cataracts, more skin cancer
» Sun cancer from UV-A and UV-B radiation that reaches earth’s
surface – worst is melanoma
• Squamous cell skin cancer and basal cell skin cancer make up
95% of all skin cancers – caused by UV-B ionizing radiation
exposure
• Malignant melanoma – occurs in pigmented areas on the body
(like moles) – 90% come from UV-A exposure Connections)
– Reduced crop yields, decreased forest productivity (for UVsensitive species)
– Reduced phytoplankton (disrupts food webs)
– Increased acid deposition/photochemical smog
– Decreased ocean uptake of CO2 by phytoplankton can
increase global warming.
Global warming
The greenhouse effect is natural and important to deep the
earth warm enough for life to exist
• Global warming occurs when humans contribute too much of
these greenhouse gases leading to a small (1-3 degree C) but
significant rise in the global average temperature.
• Analogy – Car on a sunny day
Global Warming
Greenhouse gases
CO2 (*mainly from fossil fuel burning and coal power plants, deforestation
decrease the amount absorbed by trees) – stays in troposphere for 50-120y
Methane – CH4 (from rice paddies, guts of cattle, landfills, gas leaks) – stays in
troposphere for 12-18y
Nitrous oxide N2O (from fossil fuel burning, fertilizers, lifestock waste) – stays in
troposphere 114-120y
CFCs, HCFCs, HFCs (from airconditioners, refrigerators, plastic foams) - stays in
troposphere 15+ years
Halons (from fire extinguishers) – stays in troposphere 65 years
Impacts/consequences of global warming –
Loss of species/biodiversity, loss of habitats, increased pests.
Shifts in food-growing areas, changes in crop-yields, disruption of food supplies
prolonged heat waves/droughts, increased flooding in some areas increased
human deaths (heat/disease), displacement from homes.
Rising sea levels, flooding of cities, coastal wetlands
Disappearance of forests, increased fires, changes of forest
locations/composition.
Decreased water supply/quality, increased drought/flooding
Can eventually stall the ocean heat conveyor belt which could result is
catastrophic weather changes within a few decades.
Reducing Climate change– remember prevention is always best…
Prevention: cut fossil fuel use (especially coal), shift more to natural gas,
develop renewable technologies, improve energy efficiency, reduce
deforestation, slow population growth, limit urban sprawl…
Encourage countries to cap greenhouse emission – allow
selling/trading of permits in the marketplace (similar to what we
have now w/sulfur), tax incentives/rebates/penalties
Cleanup:remove CO2 from smokestacks/vehicle emission (filter), store
CO2 by planting trees, sequester CO2 underground or in the deep
ocean…
Methane
for Sale
Relevant laws :
Kyoto Protocol (1997) – agreement among 150 nations to
reduce greenhouse gases (US does not participate!)
Montreal Protocol (1987) – 100+ countries came
together to set a time-table for phasing out CFCs.