Human Population and Sustainability

transcript

Unit 1 – Chapters 6, 1

Essential Questions

How has the population of humans changed over time?How are various countries trying to control their populations?What population issues are facing the United States specifically?What issues are facing the world with regard to rising world population?

Current World Population Growth

Approximately 7 billion people in the world310 Million AmericansEvery 5 days, the global human population increases by roughly 1 million people1.8 million babies are born800,000 people dieThis rate of growth is fairly recent

Population Growth Human population growth was slow until around 200 years agoThis J shape seen on the graph represents exponential growth10,000 years ago = 500 million people on the planetTook until 1927 to add first 2 billion people50 years (1974) for next 2 billion25 years (1999) for next 2 billion

Exponential Growth

Exponential growth expected to continue By 2050, the Earth may have 7.8 – 10.8 billion* human inhabitantsThe rate of population growth has slowed, but the world’s population is still growing exponentially at a rate of about 1.21 % a year (an average of 227,000 people per day)

*demographers make predictions which vary greatly

Population Growth Projections

Exponential Growth DistributionGrowth is distributed unevenly2010

1 % of growth occurred in (MDCs) more-developed countries (growth rate 0.17 %)99% of growth in (LDCs) less-developed countries (growth rate 1.4 %)

MDC vs. LDC Population growth

More Developed Countries

MDCUS, Canada, Japan, Australia, New Zealand, and most of EuropeHigh average income19 % of the worlds populationUse 88% of the worlds resourcesProduce 75 % of the worlds pollution and waste

Less Developed Countries

LDCAll other nations. Divided into two groups:

Moderately developed countries ( China, India, Brazil, Turkey, Thailand, and MexicoLeast developed countries (Congo, Haiti, Nigeria, and Nicaragua)

MDCs vs. LDCs

Thomas Malthus

English Clergyman, Professor, and EconomistIn 1798 observed two things

the human population was growing exponentiallythe food supply was growing linearly

Formed the following conclusionsThe human population would in time exceed the food supplyMass starvation would occur, causing human population to decrease to a sustainable levelThe cycle of population growth followed by mass die-offs would repeat endlessly

Exponential vs. Logistic GrowthExponential Growth

Occurs when a population has essentially unlimited resources to support its growth.J shaped curveEventually exponential growth is converted to logistic growth

Logistic Growth: Growth rate decreases as the population becomes larger and faces environmental resistanceS shaped curvePopulation stabilizes at or near the carrying capacity

Carrying Capacity

There are limits to population growth – the population cannot grow indefinitelyCarrying capacity: maximum population of a particular species that a given habitat can support over a given periodCultural carrying capacity: the maximum number of people who could live in reasonable freedom and comfort indefinitely without decreasing the ability of the earth to sustain future generationsAnimal populations vs. Human population

Fig. 5-14, p. 115

Fig. 5-15, p. 115

Events of the last 250 years

Fig. 6-4, p. 127

Population comparison 2010 and 2050

Major changes that contribute to increasing populations

1. Humans developed the ability to inhabit almost all areas of the earth

2. Development of agriculture (both early and modern practices) produced more food per area farmed

3. *Death rates dropped sharply due to increased sanitation (indoor plumbing, water purification) and health care (antibiotics, vaccines)* birth rates remained static

Factors driving human population growthChanges in population size

ImmigrationEmigrationCrude birth rateCrude death rate

FertilityTotal fertility vs. replacement level fertility

Life ExpectancyInfant mortalityChild mortality

Aging and disease

Population Dynamics Changes in Population Size

More births than deaths = growthMore deaths than births = declining populationEqual births and deaths = population stabilityImmigration (into)Emigration (out of)Crude birth rate

Number of live births per 1,000 people in a population in a given year

Crude death rateNumber of deaths per 1,000 people in a population in a given year

Calculating Population ChangeCalculate global population growth rate

Example 1: Worldwide, there were 20 births and 8 deaths per 1,000 people in 2009. Calculate the population growth rate (disregard immigration and emigration – why?)

CBR – CDR/10Answer in percent

Calculate growth rate of a nation or specific areaA metropolitan region has a starting population of 20,000. In the course of a year, there are 2,000 births, 500 deaths, 200 emigrants, and 100 immigrants.

(Births + immigration) – (deaths + emigration)/ total pop x 100

Doubling Time/Rule of 70The time it takes (usually in years) for the quantity of something growing exponentially to double. Works best when the population is growing at a constant rate.Doubling time = 70/annual growth rateAnnual growth rate = 70/doubling time

Example 1: Calculate the time it will take for a population growing at an annual rate of 2%Example 2: Calculate the annual growth rate if it takes 17.5 years for a population to double.

World Growth Rates

Fertility Total fertility rate (TFR)

An estimate of the average number of children born to women in a population during their reproductive years1955: 2.8 in MDC; 6.2 in LDC2010: 1.7 in MDC; 2.7 in LDC

Replacement-level fertility rateThe average number of children that couples in a population must bear to replace themselves In theory it should equal 2(replace parents)Depends on prereproductive mortality2.1 in MDCs; 2.5 + in LDCs Does not stop population growth immediately

Total Fertility Rates

Factors affecting birth/fertility ratesImportance of children as part of the labor forceCost of raising and educating childrenAvailability of, or lack of, pension systemsUrbanizationEducational and employment opportunities for womenAverage age at marriageAvailability of legal abortionsAvailability of reliable birth control methodsReligious beliefs, tradition, and cultural norms

Life ExpectancyAverage number of years a newborn infant can be expected to liveAssociated with levels of resource consumption and environmental impactsReported 3 ways: overall population, male, & female

Global life expectancy in 1955 was 48; in 2010 it was 69; 67 for men & 70 for women2010: MDCs = 77, LDCs = 67

Japan has the longest life expectancy of 83US life expectancy

In 2010 was 78; 75 for men & 81 for women Expected to reach 83 by 2050

Factors Affecting Life ExpectancyAccess to food supplies Quality of available nutritionAccess to medical advances: vaccines & antibioticsAccess to improved sanitation & safer water Exposure of pollutants/environmental hazardsExposure to HIV/development of AIDSLife expectancy gap:

Males: dangerous jobs, wars, greater biological riskDivision of labor b/w men and women becoming more evenly divided in MDCs may decrease the life expectancy gap

Infant MortalityInfant mortality rate (IMR)

The number of babies out of every 1,000 born who die before their first birthdayOne of the best measures of a society’s quality of life because it reflects the general level of nutrition and health careGlobally, IMR are decreasing. In 2009 was 46 Greatest decrease in MDCs then gradient to LDCHigh infant mortality indicates undernutrition, malnutrition, and high incidence of infectious disease (contaminated drinking water)Infant mortality rates affect TFR

Infant Mortality Rates (IMR)4 million children die before their 1st birthdayUnited States

Spends the most $ on health care, yet ranks 54th in IMRIMR dropped from 165 in 1900 to 6.4 in 2010Compare to : Sweden = 2.5; France 3.6Level of infant mortality may be related to SES

African American =13.6Native American = 8.1Caucasian = 5.8

3 factors contribute to high IMR in the USInadequate health care for poor women during pregnancyDrug addiction among pregnant womenHigh birth rate for teenage women (dropped until 2005, now increasing again)

Infant Mortality Rates

United States Population Growth

In 1900 population was 76 million, 2010 population is 310 millionBaby boom (1946 to 1964) 76 million people were added to US populationAt the peak of the baby boom the TFR was 3.7 children per womanSince 1972, TFR remains close to 2.1Population is still increasing b/c birth rates are greater than death rates and immigration is greater than emigration

TFR in the US b/w 1917 and 2010

Population Age StructureAge Structure diagrams or pyramids:

the numbers or percentages of males and females in young, middle, & older age groups in that populationFuture population growth can be predictedEach country has a unique shape, although they can be classified into general broad categories

Individuals are divided into three groupsPrereproductive (ages 0-14; bottom of diagram)Reproductive (ages 15 – 44; middle of diagram)Postreproductive (ages 45 and older; top of diagram)

The bars of the diagram represent 5 yr incrementsDemonstrate demograpic momentum

Age Structure Diagrams

Effect of AIDS on population structure

27 million deaths b/w 1981 and 20092 million deaths per yearLeading cause of death globally for ages 15 - 49Kills mostly young adults – which leads to many orphaned children (some of which are infected w/ HIV) and an odd shaped age structure diagram.Social structure and economy are affectedDecreased life expectancy

Demographic MomentumThe rate of future growth is determined by the # of females in their prereproductive years.Fast growing populations will have a wide base of prereproductive females.Slowly growing countries will have only a slightly larger base of prereproductive females and stable countries show equal levels of females in all three division (a slight in the oldest age groups)Countries with negative growth will have larger numbers or percentages of women in the postreproductive years

MigrationCountries may experience population growth stability, or decline regardless of birth and death rated due to migrationImmigration vs. emigration2009: 190 million people migrated from one country to another (60 million from LDCs to MDCs)Many MDCs continue to experience population growth due to immigration rather than TFR.Reasons for migrating:

Jobs, economic improvement, religious persecution, ethnic conflicts, political oppression, war, disease, natural disasters, environmental degradation (soil erosion, food and water shortages)

Current Status of the Worlds Population2010: 27% of world’s population was under age 15 (prereproductive)1.8 billion (1 in 4) individuals are about to enter their prime reproductive years 30% of these are located in LDCs and 16% in MDCs

MDC vs. LDC

Population Graying

Fastest growing age group are seniors (65 and older)Seniors are expected to triple by 2050 (1 of 6)This is called graying of the populationChina:

16 seniors/100 workers (2010)30 seniors/100 workers (2025)61 seniors/100 workers (2050)

What type of country will be most affected by graying populations?

American Baby Boom

Added 79 million people to the population between and 1964Make up about 36% of adult population in the US (makes them powerful in terms of economic and political power)As the boomers turn 65 the # of Americans over 65 will increase to 1 in 5

Graying of populations

Population DeclineGraying populations will contribute to more countries experiencing population declinesProblems associated with population decline

Economic growthLabor shortagesLess government revenues with fewer workersLess small/new business formationDecreased technological developmentIncreased public deficits to fund pension and heath care for the elderlyPension cutting and increased retirement ageJapan, Russia, Greece, Germany, Bulgaria, Hungary, Ukraine, Serbia, Portugal, and Italy

Population Issues

United StatesChinaIndiaIndonesiaSomoliaItalyChadJapanAustraliaSweden

Demographic Transition

A hypothesis of population changeAs countries become industrialized and economically developed, first their death rates decline and then their birth rates decline.The hypothesis contains four distinct stages (current demographers are arguing over 4 or 5 stages)Early and late stage 4 in our book, other resources refer to stage 5

Demographic Transition: Stage 1Stage 1: slow to no population growth (Pre-Industrial)Today, even the poorest LDCs have moved out of stage 1High birth rate

Cultural or religious beliefs encouraging large familiesLack of contraception Parents have lots of children to compensate for high Infant mortality Children work on the landChildren take care of parents in their old age

High death ratesdisease, famine, poor diet and hygiene, poor medical careIn rare cases (Lesotho: CBR = 25 and CDR = 23) a country will move backwards from Stage 2 towards Stage 1 due to war, famine, and AIDS

Demographic Transition: Stage 2Stage 2: rapid population growth - early modernizationA state of imbalance – more births than deathsBirth rates

Do not decrease significantlyIt takes multiple generations for the decline in infant mortality to affect the number of children families have (population momentum)

Death ratesDecrease significantly due to better sanitation, access to clean drinking water, access to health care & vaccinations,

Demographic Transition: Stage 3Stage 3: Stable Population growth– IndustrialBirth rates decline:

Increased access to contraception Infant mortality falls - less need to have a large family Industrialization and mechanization means less workers are required. Wealth increases and people are more materialistic, so want less children.Cultural, societal, and religious norms may dictate the # of childrenMore time spent on education leads to fewer children

Death ratesContinue to decrease

Demographic Transition: Stage 4Late Stage 4: Population declines and graysHigh levels of affluence & economic developmentCBR well below CDRBirth rates: very low

Family planningGood healthLater marriagesImproved status of women

Death rates: lowIncreased technological/medical advances that extend our lifespan

Demographic Transition

Fig. 6-18, p. 140

Bangladesh vs. US

Failing States

Status of Women Globally

Women handle the majority of domestic and child care work.Women handle the majority of work associated with growing food, gathering wood, hauling waterWork approximately 2/3rds of all hours; receive 10% of the world’s income and own less than 2% of propertyMake up 70% of world’s poor and 64% of illiterate adults.

Factors on Fertility

FactorsLevel of education (sons are educated, daughters often stay home to work)Ability to read (illiterate = 5-7 children)Access to birth control/family planningAbility to earn an incomeSocieties that respect the rights of women

Family PlanningProvides educational and clinical services that help people choose how many children and the spacing of those children Been a major factor in stabilizing populationsDecreases abortions, death rates of mothers, and miscarriages during pregnancyUN states 55% drop in fertility in LDCs is a result of family planningFor each dollar spent on family planning, countries may save b/w $10 - $16 in health, education, and social services by preventing unwanted births.

More Family Planning Needed42% of pregnancies in LDCs are unplanned and 26% end in abortion.In United States almost ½ of annual pregnancies are unintended and result in 1.4 million unplanned births and 1.3 million abortionsLDCs: many lack access to family planning servicesFamily Planning Services should be expanded to sexually active unmarried women and teenagersPrograms to educate men about the importance of having fewer children and taking more responsibility for raising them.

Family Planning as Population ControlFamily Planning could prevent

52 million unwanted pregnancies22 million induced abortions1.4 million infant deaths142,000 pregnancy related deaths

Could reduce the global population size projected for 2050 by more than 1 billion peopleAverage cost: $20.00 per family per year

Slowing Human Population Growth

Decrease poverty through economic developmentElevate status of womenEncourage family planning and reproductive health

Overpopulation vs. OverconsumptionOverpopulation: the sheer number of people on the planet is outstripping the Earth’s ability to support usOverconsumption: in affluent MDCs the high rate of use of materials is a growing problem

Economic terms

Economic growth - ↑ in nation’s output of good and servicesGross domestic product (GDP) – annual market value of all good and services produced within a countryPer capita GDP – the GDP divided by the total population at mid-yearEconomic development – the effort to use economic growth to improve living standards

LDCs vs. MDCs

LDC81% of the world’s populationLow income per personLow GDP and per capita GDPIncludes moderately developed countries (China, India, Brazil, Turkey, Mexico) as well as least developed countries (Haiti, Congo, Nicaragua)

MDCHigh income per personHigh GDP and per capita GDPUse 88% of resources, produce 75% of waste and pollution

DefinitionsEnvironment – everything around us including both living and non-living factors with which we interact in a complex web of relationships that connect us to one another and to the world in which we live.Ecology – the study of how living things interact with one another and their environmentEcosystem – the set of organisms within a defined area that interact with one another and their environment of non-living matter and energy.Biotic – living components of an ecosystemAbiotic – non-living components of an ecosystem

SustainabilityLiving on Earth in a way that allows us to use its resources without depriving future generations of those resources3 Keys to sustainability

Using the energy from the sun to power our needsProtecting the Earth’s biodiversity that provides ecosystem services including water and air purification and pest controlProtecting the cycling of chemicals to keep our environment in balance, upsetting the chemical cycling balance may produce long-term negative effects

Aldo Leopold and Garrett HardinLeopold

Wrote A Sand County Almanac in 1949Promoted a “land ethic” in which humans are ethically responsible for serving as the protectors of nature

HardinWrote an essay “The Tragedy of the Commons” in 1968He argued that rational people will exploit shared resources or commons

Components of Sustainability

Natural Capital – the natural resources and services that keep us and other organisms alive and support our human economies. Natural Resources – materials and energy in

nature that are essential or useful to all humans

Natural Services – processes in nature which support life and human economies (water and air purification, renewal of topsoil etc)

Human impact on Natural ResourcesDecreased biodiversityIncreased use of net primary productivityIncreased genetic resistance in pest species and disease causing bacteriaElimination of natural predatorsIntroduction of non-native/invasive speciesUse of renewable resources that outpaces replacement timesDisruption of natural chemical cycling and energy flowUse of fossil fuels as our primary source of ESolutions: Scientific/Political/Individuals

Renewable vs. Non-Renewable ResourcesResource – anything that we can obtain from the environment to meet our needs and wantsPerpetual – solar energyRenewable –can be replenished through natural processes (timber, fish populations)Nonrenewable – exist in a fixed quantity in the earth’s crust (coal, oil, Cu, Al)Reuse vs. Recycle

Throw away , Recycle , Reuse Which is the best option and why?

PollutionChemicals or other agents (noise, heat) present at a level that is harmful to health, survival, or activities of humans or other organismsCan be naturally occurring (volcanic eruptions, forest fires) or through human activities (burning of fossil fuels, pesticides, fertilizer runoff)Point sources – have single identifiable sources (smokestack from a power plant)Non-point sources – are difficult to identify due to the large number of sources that can contribute (pesticide overspray, fertilizer runoff, trash in waterways)

Point Source Pollution

Non-Source Point Pollution

Effects of pollutionDegradation of life-support systems (water, air, soil)Damage to wildlife (habitat/extinction)Damage to human health (cancer/asthma)Damage to property (acid rain erodes gravestones, invasive species)Nuisance pollution (smell, noise etc)

Pollution Cleanup and PreventionCleanup = cleaning up or diluting pollutant

Temporary fix and population levels may outpace cleanup effortsRemoves pollution from one environment, but is disposal can cause pollution in another environmentPollutants become dispersed throughout the environment and are then too difficult to clean up

Prevention = reduces or eliminates the production and release of pollutants

Works betterProvides long term solutionMore economical in the long run than cleanup

Types of Resources

Private property – individuals or companies own the rights to land/mineralsCommon property – owned by a large group of individuals (NPS – 1/3 of land in US is common property)Open-access renewable resources – owned by none and available to all. Examples: air/atmosphere, ground water, open ocean and marine life

Tragedy of the Commons

Many common property and open-access resources have been degraded

Large numbers of people accessing or using these resources degrade resources to the point of no return

SolutionsLimit use of resources to levels well below the sustainable yield (requires regulation)Convert open access renewable resources to private ownership (is this practical?)

Ecological Footprint

The amount of biologically productive land and water needed to provide the people in a particular country or area with an indefinite supply of renewable resources and to absorb and recycle the wastes and pollution produced by such resource use

i.e. use of resources and the resulting environmental impact Individual – measures your personal impactPer capita – the average ecological footprint for an individual in a given area or country

Ecological Footprints Worldwide

Ecological Footprint by Country

Ecological Footprint cont.

The World’s ecological footprint is currently 1.3 Earths Expected to need 2 Earths by 2035US can only support 186 Million people at our current level of consumption – what is our current population?Only factors in use of renewable resources

Ecological Footprint by Country

IPATIPAT is a model that shows how population size,

affluence (consumption of resources), and technology (both harmful and beneficial for the environment) impact the environment

Impact (I) = Population (P) x Affluence (A) x Technology (T)

Includes both renewable and nonrenewable resourcesTechnology

Coal fired power plantsPollution control and prevention (scrubbers)

Impacts of IPAT

Depletion of topsoil through increased agricultural productionDrilling more and deeper wellsIncreased energy use to transport fossil fuels, water, minerals and foodPopulation growth and increased consumption as more countries become more affluent (China and India) will exacerbate the problem

Affluence

Drawbacks to increased affluenceHigh levels of consumptionHigh levels of pollutionUnnecessary waste of resources

Benefits of increased affluence Increased educationCleaner water and airAbundant food supplyIncreased life spansProtection of some endangered species

Tipping Point

Ecological tipping point – an irreversible shift in the behavior of a natural systemEnvironmental degradation has time delays between our actions now and the deleterious effects later

Long-term climate changeOver-fishingSpecies extinction

Cultural Changes

12,000 years ago: hunters and gatherersThree major cultural events

Agricultural revolutionIndustrial-medical revolutionInformation-globalization revolution

All three have enabled people to meet our increased wants and needsCurrent need for a sustainability revolution

Four Basic Causes of Environmental Problems

1. Population growth2. Wasteful and unsustainable resource use

Average American consumes 30X as much as the average Indian and 100X the average person in the world’s poorest countries

3. PovertyIncreased environmental degradation due to large populations that use resources unsustainablyMalnutrition Premature deathLimited access to adequate sanitation facilities and clean water

Four Basic Causes of Environmental Problems

4. Failure to include the harmful environmental costs of goods and services in market prices

Companies do not pay the environmental cost of resource useGoods and services do not include the harmful environmental costsCompanies receive tax breaks and subsidiesEconomy may be stimulated but there may be a degradation of natural capital

Environmental Worldviews and Ethics Environmental worldviews are the set of assumptions and values that reflect how you think the world works and what you think your role in the would should beEthics – beliefs about what is right and wrong with regard to how we treat the environmentEnvironmental equity – the fair distribution of the Earth’s resourcesEnvironmental Justice – a social movement and field of study that works toward equal enforcement of environmental laws and elimination of disparities in how pollutants and other environmental harms are distributed among the various ethnic and SES groups

Human Population and Sustainability

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