Presentation on theme: "Counting the Worlds Population"— Presentation transcript:
1Counting the Worlds Population Population GeographyCounting the Worlds Population
2A Lesson In Exponential Growth! Bacteria BottlesA Lesson In Exponential Growth!This puzzle illustrates the concept of exponential growth using bacteria. Bacteria multiply by division. One bacterium becomes two. Then two divide into four; the four divide into eight, and so on. For a certain strain of bacteria, the time for this division process is one minute. If you put one bacterium in a bottle at 11:00 p.m., by midnight the entire bottle will be full.John Madden /10
3Bacteria Bottles1) When will the bottle be half-full? How do you know?2) Suppose you could be a bacterium in this bottle. At what time would you first realize that you were running out of space? Why?John Madden /10
4Bacteria BottlesSuppose that at 11:58 some bacteria realize that they are running out of space in the bottle. So they launch a search for new bottles. They look far and wide (working at the speed of light). Finally, offshore in the Arctic Ocean, they find three new bottles! Great sighs of relief come from all the bacteria. This is three times the number of bottles they’ve ever known. Surely, they think, their space problems are over. 3) Is that so? Explain why the bacteria are still in trouble. Since their space resources have quadrupled, how long can their growth continue? (Remember it takes an hour to fill up the first bottle)John Madden /10
5Bacteria Bottles Ready For The Answers??? 1) The bottle will be half-full at 11:59 p.m. because the doubling time is one minute and the bottle will be full at midnight.2) At 11:55 p.m., when the bottle was only 3% full and 97% empty, would it be easy to perceive that there was a space problem?John Madden /10
6Bacteria Bottles3) With space resources quadrupled, the bacteria have two more doubling times, or two minutes before they will run out of space.11:58 p.m. : Bottle 1 is one-quarter full.11:59 p.m. : Bottle 1 is half-full.12:00 a.m. : Bottle 1 is full.12:01 a.m. : Bottles 1 and 2 are full.12:02 a.m. : Bottles 1, 2, 3, and 4 are fullJohn Madden /10
7Bacteria BottlesSo, what does this suggest about Human Population Growth??John Madden /10
10Bacteria BottlesHuman Population Growth!YearJohn Madden /10
11Why study population?Over the last 12,000 years of history, population is increasing faster than ever before!In the last 2000 years, the Earth’s population has increased 10 timesIn the last 50 years, Earth’s population has doubledWill this population growth increase to a level that will cause a global crises?
13Population Basics Demography: the study of human populations Currently 7 billion people on the EarthThis study is very important because the number of people in a country can influence the infrastructure and support systems of a countryPopulation EquationScale of inquiry: size of a geographic investigation (world, regional or local) important to understandOn global scale, demographers focus on where earth’s populations are increasing fastest and where they are expanding more slowly-least stable areas experiencing the fast growth
14Population FactsAbout 81% of earth’s population lives in poorer, less developed countriesThe only two countries to have more than 1 billion people are India and China1 in 3 of earth’s people live in China or IndiaNearly 3 of every 5 people live in Asia and EuropeLargest population concentration is East Asia-nearly 25% of earth’s total population: most people subsistent farmersThird largest population cluster is Europe: most people are urban dwellers
16Population Distribution Defined: pattern of people across the earth’s surface-where they liveOver history, people have been unevenly distributed-Why?Few people live in desert/tundraAbout 75% of global population lives on 5% of worlds surfaceArea people can live is called the ecumene50% of earth’s people live in cities
18World Areas of Population Density East Asia: China, South and North Korea and Japan1.5 billion people with 1.3 billion in ChinaSouth Asia: India, Pakistan and BangladeshWithin 50 years, India will pass China as most populace country on planetSoutheast Asia: Vietnam, Indonesia and ThailandWestern and Central Europe: mostly urbanNortheastern United States and Canada: includes megalopolis from Boston to Washington D.C.
21Population Density Defined: number of people in a particular land area Arithmetic densityTotal number of people divided by total land areaExample: Egypt has arithmetic density of 177 people per square mile but only 98% of population lives on 3% of landPhysiological densityNumber of people per unit of arable landHelps in analyzing amount of farmland available to populationU.S. physiological density is 340 people per square mile; Japan is 7,000 people per square mile; Egypt's is 3,000 people per square mileAgricultural densityNumber of farmers per unit of arable landHigh density meant many farmers are on each piece of farmland; low density suggests the presence of larger farms
26Adding up population numbers Equations exist to allow demographers to determine actual populationsDemographic accounting equationsGlobal population accounting equationP1=P0+B-DP1 is size of population at end of interval of measurementP0 is size of population at start of interval of measurementB is number of births during interval of measurementD is number of deaths during interval of measurementSubglobal population accounting equationP1=P0+B-D+I-EP1, P0, B and D same as aboveI is number of immigrants moving into region during interval of measurementE is number of emigrants moving out of region during interval of measurementImmigration: people moving into a region/countryEmigration: people leaving a region/country
27Math ExampleCountry A has 1 million people in Over the next 10 years 75,000 babies are born; 50,000 people die; 10,000 people move into the country; and 5,000 people exit. What would the population be in 2000?P1=1,000,000+75,000-50,000+10,000-5,000= 1,030,000 people
28Population PyramidsAlso known as age-sex structures used to evaluate the distribution of ages and genders in a given populationShows sex ratio (number of males compared to females in a population) at ANY GIVEN TIME!Cohorts (people of the same age) are split between men and women on the pyramidUsed to analyze population and/or predict future populationCannot determine country size from pyramids but can determine placement in DTM
29Population PyramidAlgeria’s pyramid has a wide base and a flattened top. What does that mean?Italy’s pyramid is wider in the middle than at the base. What does that mean?What expectations do you have for a population pyramid from 2025?
31Expanding Populations ContractingPopulationStable Population
322025 Predictions Did Algeria’s growth rate decrease? How can you tell? What happened to Italy’s population?Graying population: when a population has more middle-aged and older people than young people. Why is this a problem?
35Fertility and Mortality Fertility: reproductive behavior of a populationImpacted byFecundity of populationDiet and nutritional intakeEconomic and industrialization levelsSociocultural factors like age of marriageMortality: death related behavior of a population
36Population Key TermsCrude Birth Rate (CBR): number of live births per 1,000 people in a yearCrude Death Rate (CDR): number of deaths per 1,000 people in a yearLDC’s average CDR of 20 while MDC’s average CDR of 10Infant mortality rate (IMR): number of infant (children who die before their first birthday) deaths per 1,000 live birthsLife expectancy: average number of years to be lived by a personFecundity: ability of a woman to conceive (usually 15 to 45)General fertility rate (GFR): number of births per 1,000 women in the fecund yearsTotal fertility rate (TFR): predicted number of births a woman will have as she passes through fecund yearsTFR has declined on every continent but Africa over the last 50 yearsExample : in 1975 Mexico’s TFR was 7 but in 2009 had dropped to 2.37 – in China in 1970 TFR was 6 but 1.6 in 20092006 TFR rate was greater than 3.0 across the globe2006 TFR rate in U.S., Europe and China was 2.1 or less
37Fertility Rates Country Growth Rate % Per Year Birth Rate per 1,000 Death Rate per 1,000United States0.88314.68.25Japan0.1397.879.26China0.62913.717.03Russia-0.47411.0316.06Australia0.80111.907.62Mexico1.14220.044.78South Africa-0.50117.7122.70India1.57822.226.40United Kingdom0.27610.6510.05
38Replacement-Level Fertility A TFR of 2.1 is considered replacement-level fertility meaning parents will produce the number of children needed to replace themselvesTFR of 2.1 causes zero population growth (ZPG)Rate of Natural Increase (RNI) is growth rate of a population using the formulaCBR-CDR/10Does NOT include immigration and emigrationRNI that equals zero means population won’t grow or declineGlobal RNI in 2006 was 1.2%More developed countries had an RNI of 0.1%Less developed countries had an RNI of 1.5%Africa’s RNI in 2006 was 2.3%RNI does NOT include migration
40Rule of 70 Defined: time that it takes for a population to double Equation: Divide 70 by current growth rate of population70/ current growth rate = doubling timeExamples70/5% = 14 years70/2% = 35 years
42A Graying PopulationWhat would be the positives and negatives of a graying population?Dependency ratio: show relationship between dependents and nondependent'sDependents: people who depend on workers for survivalNondependent's: people who can support themselves through workHigh ratio means more people are dependent than workingFewer people to pay taxesSocial security dependency2000 was first time in history that people under 14 years of age were outnumbered by people over 60
44Carrying Capacity and Overpopulation Carrying capacity: number of people an area can sustain or supportJapan: imports foodSaudi Arabia: desalinizes water to increase carrying capacityOverpopulation: when a region’s population outgrows its carrying capacityResource availability very important but resources can be indigenous or importedSome areas have resources to produce more than they harvest-lack of infrastructure, political/economic stability, etc.
45Other population growth consequences In China, boys now outnumber girls 119 for every 100 girls born – natural average 105 to 100
46Population growth theories Thomas MalthusWrote An Essay on the Principle of Population, 1798Argued that global population was growing exponentially while food supplies were growing arithmeticallyAdvocated birth control and celibacy (positive checks) and warned of war, starvation and disease (negative checks)Said population growth caused poverty, crime and miseryKarl MarxSaid population wasn’t problem-the problem was unequal distribution of resources and wagesSaid population growth was caused by poverty and unequal distribution so if things were distributed evenly, population wouldn’t growEster BoserupBelieved overpopulation problem could be solved by increasing number of subsistence farmers because when humans are faced with starvation, they WILL develop new technologyNeo-MalthusiansArgue that sustainable development hinges on Malthusian idea that human population must reach a “sustainable” level within carrying capacity
49Is population growth a problem Is population growth a problem? Two very different, but supportable ideasYesMost of our increased food availability is tied to non-sustainable resources like oilHumans bring about environmental destructionI=PATEnvironmental Impacts= Population size times affluence times technologyMost humans live a lifestyle that is not sustainableNoFood supplies have increased - in 1970 average caloric intake was 2,435 but in 2000 average was 2,087Countries like China have industrialized quickly BECAUSE of increased population that create workers and a marketHumans are the ultimate resource and will continue to advance to support ourselves
51Population ExplosionOver last three centuries, earth has experienced a population explosionCurrently population is growing at exponential rateExponential growth: the more people that are added, the faster the population is growingLinear (a.k.a. arithmetic) growth: constant fixed rate of growthIn 1750 world population was 700 millionIn 200 years (1950) population grew to 6 billion
52Historical population growth 10,000-12,000: first agricultural revolutionHumans domesticated cropsLed to development of cities and stationary settlementsCity development leads to population growth1700’s Industrial Revolution and second agricultural revolutionIndustrial revolution was new technologies and industries-started in EnglandMove people into citiesSecond industrial revolution improved fertilization and food storage increasing food supplyAllowed more people in cities because extra food is grown can be sold in cities
54What causes population growth? Medical AdvancesInoculations, better health care, new medicationsQuantity and quality of foodAgricultural technology has increased availability and health benefit of foodEthnic and religious issuesMany cultures forbid birth control or abortionSome cultures have beliefs that spread diseaseEconomic issuesAgricultural base economy=higher birth rateIndustrial or service base=low or no population growth
55Population Projections for the Future Different growth scenarios existMedium growth (most accepted)2050=9 billion; 2100=9.5 billionLow-growthPopulation will begin declining: 2050=7.5 billion; 2100=5.1 billionHigh-growth scenario2050=11 billion; 2100=16 billion
57Demographic Transition Model Defined: DTM predicts changes in birth, death and natural increase rates in countries as they transition or matureBased on assumption that economics drive demographic change and that all countries will pass through five stages of demographic transition or changeThe three measurements in the model are CBR, CDR and RNI
58Stage 1: Low Growth (high stationary stage) Hunter and Gatherer SocietiesHigh CBR and CDR leading to low RNIFluctuation in CBR and CDR because of disease, famine and warUsually characterizes a subsistence farming country without industrialized economy
59Stage 2: High Growth (Expanding Stage) Agricultural SocietiesHigh CBR: children are still needed on the farms to helpDeclining CDR: CDR starts to drop as new health care systems arrive-industrialization has begun but CBR has not fallen because children still seen as economic necessityRNI increases because same high number of births is occurring with fewer deaths to match the high birth numbersPopulation expansion is high
60Stage 3: Moderate Growth (expanding stage) Industrial SocietiesDeclining CBRCBR drops because families’ decisions to lower number of children they are havingRNI is decreasing but still greater than zero so population is still expanding
61Stage 4: Low Growth (low stationary stage) Tertiary SocietiesCBR and CDR meet at equal levels (equilibrium) but this time they are at low levelsRNI is lowSeen as modern society stage with zero population growth
62Criticisms of DTMBased on England's transition from subsistent economy to industrialized societyAll countries may not pass through this systemSome African countries received medicines and food from more developed countriesEngland took 100 years to go from stage 2 to 3 and countries today are being pushed at a much faster rateWe don’t know exactly where the 5th stage is headed. It includes a decline in the CBR as seen in modern countries like France and Germany-something that shows the graying population but what else will happen?
63Demographic Momentum Also known as hidden momentum Occurs in many developed countries when population continues to grow even after replacement-fertility is reachedHappens when people live longer-even though TFR is 2.1 to 2.5 population is still growing because people are dying at slower ratesMakes zero population growth difficult to attain
64Global DTM All countries on globe are out of stage 1 Most Latin American and Asian countries are in stage 3Most African countries remain at high growth in stage 2Many Europeans at end of stage 4Japan, Germany and France are facing a fifth stage or the graying population problem
66Negative Checks on Population Three basic categories: natural disasters, war or political turmoil and economic issuesBlack Plague: killed 40% of European population and 13 million Chinese in 1300sIrish potato famine: killed almost 50 percent and caused massive emigrationHIV/AIDS: since 1980s has risen to pandemic (disease affecting very large amounts of people in large area) levelsIn 2005, 39 million people living with HIV, nearly 3 million died from AIDSIn Sub-Saharan Africa, 19% of all adults are infectedChina expected to see nearly 11 million infections by 2010More than ½ of 5 million new cases every year are people ages 15-24In 2010 were 25 million AIDS orphans
68Population PoliciesPro-natalist policies promote reproduction and bigger families-sometimes called expansive policiesExamples include tax breaks for children or antiabortion lawsFound in Europe, 1950s China and modern United StatesAlso found historically and in susbistent type economiesAnti-natalist policies discourage high fertility rates-sometimes calls restrictive policiesExamples include easily accessible abortions and contraceptives, or government policies limiting childrenExamples include India and China
70Global population control 1984 UN population conference held in Mexico influenced by new technologies to increase global food production and China’s recent enactment of one-child policy1994 conference in Egypt proposed the Cairo Strategy-Teaching contraceptive uses in schools in poorer countriesCairo Strategy has been very controversial with certain conservative groups2004 conference declared the key to limiting population growth is to empower women through education and economic parity (equality)
72Population MovementIn the modern world, friction of distance (difficulty of distance) has been reducedProcess of coming together even though distances are not decreasing is called space-time compressionSpatial interaction is the interconnectedness of two placesMigration: permanently moving from home region and crossing an administrative boundary
74Why do people migrate?Migration stream is pathway from a place of origin to a destinationMany develop because of information exchange between peopleUsually found with migration counter streamPush factors: reasons people leave a placeExamples: high taxes, high crime rates and abusive governmentsPull factors: reasons people go to a new placePlace desirability: possession of positive features making people want to move thereExamples: affordable real estate, being near family member, good schools
75Voluntary vs. Forced Migration Voluntary MigrationOccurs when migrants have an option of whether or not to moveUsually not associated with violence or abusive governmentsExample: a new job, moving to be near familyForced MigrationEmigrants pushed from landRefugees: migrants fleeing some form of persecution or abuseInternational refugees: fell country to move to another countryIntranational refugees: abandon homes but remain in their country to escape persecutionSometimes called internally displaced peoples
76Brief history of migration About 3% of worlds people have migrated from their countries of originNorth America, Oceania and Europe have net immigrationAsia, Africa and Latin America have net emigration50% of Southwest Asia’s population are immigrantsU.S. had three major waves of immigrationColonial era ( ) primarily from Europe and Africa and was both voluntary and involuntary19th century primarily from EuropeBefore 1840 England, ’s German and Irish20th century1907 northern and western Europe and Russia; ’s Asia leading source of immigrants, 1980’s Latin America primary sourceImmigration altered by Quota Act of 1921 which allowed highest number of immigrants from European countries and discriminated against Asians and other regions
78Internal Migration Defined: movement within a country Interregional migrationMoving from region in the country to another regionIntraregional migrationMoving within a region, such as from a city to a suburbUrban migrationMigration from farms to cities
79Migration Selectivity Often, migration fits into a pattern based on age, income and other socioeconomic factorsDefined: evaluation of how likely someone is to migrate based on personal, social and economic factorsMost influential factor is ageMost people move 12 times in their lifetimes, ½ before age 25Brain Drain: net out-migration from one place of most educated workers who leave for more attractive placesGuest Workers: people let into a country to work jobs native people don’t necessarily want to do like heavy, dangerous or disagreeable work
80Ravenstein’s Migration “Laws” Late 1800s, British geographer Ernst Ravenstien identified 11 generalizations about migration-some still apply todayThe majority of migrants travel short distancesStep migration: person has a long distance goal in mind and achieves it in a series of small stepsIntervening opportunity: when an opportunity is found along destination that journey is stoppedIntervening obstacles: barriers in migration journey like financial problems, roadblocks, immigration requirements and wars
81Ravenstein’s “Laws”, cont. Migrants who are traveling a long way tend to move to larger cities than smaller citiesLarge city has more opportunities creating an almost magnetic pullKeep in mind, Ravenstein was writing during height of industrial revolutionRural residents are more likely to migrate than are urban residentsTrue in Ravenstein’s time because of industrial revolutionSeen in many developing countries like China and Brazil
82Last two “Laws”Families are less likely to migrate across national borders than are young adultsIt is easier for single people to migrate than whole familiesSinge people less encumbered with responsibilitiesEvery migration stream creates a counter streamNet migration is the number of people in the original flow minus the number of people in opposite flow (counter stream)Caused by many factorsExample: Jews leaving Germany before WWII who were captured at borders and forced to return or young boy from rural setting who moves to city and then returns to rural area after trying city life
83Chain MigrationOccurs when people migrate to be with other people who migrated before them and with whom they feel some tieTie can be religious, familial, cultural, ethnic or any type of connectionMost common type of migration to the U.S.