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Part two review. Human Population Dynamics (10-15%)

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Presentation on theme: "Part two review. Human Population Dynamics (10-15%)"— Presentation transcript:

1 Part two review

2 Human Population Dynamics (10-15%)

3 The Human Population

4 More than 6.3 billion people currently * U.S 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

5 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

6 (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

7 Population growth rates cont increase populationdecrease population births deaths immigration 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

8 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=( ) + (0.001 – 0.01) r = – = or –0.4% per year

9 Growth Rate (% per Year) Doubling Time in Years 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.

10 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

11 PreindustrialTransitionalIndustrialPostindustrial

12 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


14 Developed Countries Canada, U.S., Australia, Western Europe (Denmark) Developing Countries Latin America, China, Africa (Kenya) 1/5 of the worlds pop. Lives in absolute poverty, illiterate, lack clean H 2 O and dont have enough food 80% of worlds pop. Lives in developing co. and growing.

15 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

16 Survivorship – many women in developing countries have a large number of children because many of the children dont survive childhood due to high infant mortality rate – **which is the single most important measure of a societys 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.

17 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 worlds infant mortality rate has dropped sharply.

18 **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 societys 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.

19 Age-structure diagram

20 Population size Strategies for sustainability Family planning = birth spacing, birth control, Health care for pregnant women and infants; Empowering women = education, Womens rights; offer incentives/penalties to slow population growth Thailand – cut population growth rate in half in 15 years of family planning. US – baby-boomers, , 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 – worlds first national family planning program in 1952 – disappointing b/c poor planning, low status of women,

21 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 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 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 Sustainability


23 Layers of the Atmosphere Most GassesWeather Decreasing ATM pressure

24 Composition of the troposphere 78% N 2 20% O 2 Less than 2% H 2 O vapor (.01%-4%) Argon gas (1%) CO 2 (0.04%) Trace gases

25 Stratospheric Ozone Formation of stratospheric Ozone – molecular oxygen (O 2 ) reacts with UV-radiation in stratosphere, and breaks up into O-atoms…those then react w/O 2 in the atmosphere to form O 3 (ozone)

26 Ozone (O 3 ) 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 O 3 is like sunscreen for the earth. Tropospheric ozone is BAD If we breath it, it causes lung damage It is also a greenhouse gas

27 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);

28 Causes of ozone depletion – Chlorine from CFCs (mainly refrigerators/air conditioner coolants) *some also from Halons (fire extinguishers), methyl bromide (fumigant), CCl 4 (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-Os combine to form stable O 2 – Cl then goes on the destroy another ozone molecule (can last in stratosphere destroying ozone)

29 Ozone thinning in Antarctica, during the winter *REMEMBER their winter is OUR summer (June-August); ice crystals collect ClOs, but O doesnt break free (b/c dark, no UV radiation to split it apart) so become more stable Cl 2 O 2 …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 Cl 2 O 2 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

30 Effects of ozone depletion – Worse sunburn, more eye cataracts, more skin cancer » Sun cancer from UV-A and UV-B radiation that reaches earths 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 CO 2 by phytoplankton can increase global warming.

31 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

32 Global Warming Greenhouse gases CO 2 (*mainly from fossil fuel burning and coal power plants, deforestation decrease the amount absorbed by trees) – stays in troposphere for y Methane – CH 4 (from rice paddies, guts of cattle, landfills, gas leaks) – stays in troposphere for 12-18y Nitrous oxide N 2 O (from fossil fuel burning, fertilizers, lifestock waste) – stays in troposphere y CFCs, HCFCs, HFCs (from airconditioners, refrigerators, plastic foams) - stays in troposphere 15+ years Halons (from fire extinguishers) – stays in troposphere 65 years

33 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.


35 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 CO 2 from smokestacks/vehicle emission (filter), store CO 2 by planting trees, sequester CO 2 underground or in the deep ocean…

36 Methane for Sale

37 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.

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