Part two review

Human Population Dynamics (10-15%)

The Human Population

• 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

China &

India

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 decrease population births deathsimmigration 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

Growth Rate(% per Year)

Doubling Timein Years

0.1 700

0.5 140

1 70

2 35

3 23

4 18

5 14

6 12

7 10

10 7

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.

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:

In 140 years, the population will be 40,000 people.SHOW YOUR WORK!!!!!!!!!

(70 years)(2) =140 years 

2 D.T. 40,000

1 D.T. 20,000

In 70 years the population will be 20,000

70/rate =70/1% =70 years to double

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• 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 futureChina – 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,

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 peopleDefend the right of all young people to enjoy their sexual lives free from ill-

health, unwanted pregnancy, violence and discrimination.

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.

Cairo, Egypt, September 1994 Sustainabilit

y

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Layers of the Atmosphere

Most GassesWeather

Decreasin

g ATM pressure

Composition of the troposphere• 78% N2

• 20% O2

• Less than 2%• H2O vapor (.01%-4%)• Argon gas (1%)• CO2 (0.04%)• Trace gases

Stratospheric 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)

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.

Tropospheric ozone is BAD• If we breath it, it causes lung damage• It is also a greenhouse gas

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 UV-sensitive species)

– Reduced phytoplankton (disrupts food webs)– Increased acid deposition/photochemical smog– Decreased ocean uptake of CO2 by phytoplankton can

increase global warming.

Global warming

• 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

The greenhouse effect is natural and important to deep the earth warm enough for life to exist

Global WarmingGreenhouse gases

CO2 (*mainly from fossil fuel burning and coal power plants, deforestation decrease the amount absorbed by trees) – stays in troposphere for 50-120yMethane – CH4 (from rice paddies, guts of cattle, landfills, gas leaks) – stays in troposphere for 12-18yNitrous oxide N2O (from fossil fuel burning, fertilizers, lifestock waste) – stays in troposphere 114-120yCFCs, HCFCs, HFCs (from airconditioners, refrigerators, plastic foams) - stays in troposphere 15+ yearsHalons (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 wetlandsDisappearance of forests, increased fires, changes of forest locations/composition.

Decreased water supply/quality, increased drought/floodingCan 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.