APES Study Guide Unit 2B - Human population and Urbanization

Birth Rate (BR)

the number of live births per 1,000 people in a population per year

Death Rate (DR)

the number of deaths per 1,000 people in a population per year

Growth Rate (GR)

[(Births + Immigration) – (Deaths + Emigration)] /10

• All numbers per 1000 of population

• World Growth Rate = (16 – 8)/10 = 0.8%

Natural increase

the difference between the number of births and the number of deaths in a population over a specific period of time.

Mortality

the rate at which individuals in a population die over a specific period of time

Natality

The rate at which new individuals are added to a population through birth, hatching, or germination.

Immigration (Immigrate is usually used to mean "to come to a country to live there.")

the movement of individuals into a new population or habitat

• My family immigrated to America when I was 12.

Emigration (Emigrate is usually used to mean "to leave a country to live elsewhere.")

defined as the act of permanently leaving a country or region to settle elsewhere (focusing on the departure point or origin)

• My parents emigrated from Peru in the 1950's.
  
  

Population momentum effect

the tendency of a highly fertile population to continue growing for decades, even after fertility rates decline

Demographic transition model

explains how a country's birth rates and death rates change as it moves from a pre-industrial economy to an industrialized on

Prenatal

occurring, existing, or relating to the period before birth, specifically during pregnancy

Postnatal

occurring or existing after birth

Infant mortality rate (IMR)

# of babies out of 1000 born who die before their 1st birthday

Age structure diagram

One way to visually represent the number of individuals within specific age groups for a country, typically expressed separately for males and females

Total fertility rate (TFR)

avg. # of children a woman typically has during her reproductive years

Replacement level fertility

# of children a couple must bear to replace themselves

Heat Island Effect

Cities are warmer than the surrounding rural areas

Urban Sprawl

The movement of urbanized areas into rural areas

Zoning

A planning tool used to separate industry and business from residential neighborhoods.

Smart Growth

an urban planning and transportation theory that concentrates growth in the center of a city to avoid urban sprawl

Urban runoff

generated from rain and snowmelt that flows over land or impervious surfaces

Impervious surfaces (such as paved streets, parking lots, and building rooftops, and does not soak into the ground)

any hard, man-made structure or compacted ground that prevents or greatly reduces the flow of water into the soil

Infiltration

the process where water from precipitation or irrigation on the ground surface soaks into the soil

Porous

describes a material—such as soil or rock—that contains open spaces, voids, or pores capable of holding water, air, or other fluids

Rain Garden (such as your driveway, patio, or sidewalk)

a planted shallow depression that uses water-tolerant native plants and landscaping to soak up stormwater flowing from downspouts or hard (impervious) surfaces

Best Indicators for quality of life

Infant mortality(the number of babies that die before age 1 per 1,000 live births) and life expectancy(the average number of years a person is expected to live)

Characteristics of a less developed country

low industrialization, low per capita income, and rapid population growth

Characteristics of a developed country

high per capita income, slow or stable population growth, and heavy resource consumption

The reason for the rapid growth of the human population of the last century

a dramatic drop in death rates

Reasons for declining TFR over the last half century

socioeconomic modernization, delayed childbearing, and shifting societal priorities

Demographic factors often associated with high IMR

• Maternal Age: Risk peaks in teenage mothers (under 15) and older mothers (ages 45–49), driven by biological immaturity or age-related pregnancy complications.

• Race and Ethnicity: In the United States, IMR shows persistent racial disparities, with the highest rates historically found among Black (10.8 per 1,000 live births) and American Indian/Alaska Native infants (8.6 per 1,000 live births).

• Maternal Education and Income: Lower educational attainment and household poverty strongly correlate with higher IMR, though racial disparities persist even when controlling for income and education levels.

• Marital Status: Unmarried mothers experience higher rates of infant mortality, which often tracks with lower baseline access to financial and social support resources.

• Birth Spacing and Parity: Short preceding birth intervals (spacing pregnancies too closely) and high fertility rates are major predictors of infant vulnerability.

• Infant Biological Sex: Male infants generally exhibit slightly higher mortality rates (2.88 per 1,000) compared to female infants (2.50 per 1,000).

Demographic factors often associated with high total fertility rate (TFR)

disparities in maternal health, socioeconomic status, and systemic support

Reasons why TFR drops

• Empowerment of women: Increased access to education and career opportunities delays childbearing.

• Cost of child-rearing: Urbanization and economic development shift children from economic assets (labor) to economic liabilities.

• Access to healthcare: Widespread availability of family planning, contraceptives, and reproductive healthcare.

• Lower infant mortality: As more children survive into adulthood, parents choose to have fewer total births.

Demographic statistics associated with high quality of life

• High life expectancy: Reflects robust healthcare, nutrition, and safety.

• Low infant mortality rate: Indicates strong prenatal and pediatric care systems.

• High literacy and education rates: Demonstrates widespread socioeconomic access.

• Low Total Fertility Rate: Often correlates with higher gender equality and economic development.

Reasons why replacement-level fertility doesn't equal 2

• Replacement level is roughly 2.1 rather than a perfect 2.0 due to several factors:

• Infant and childhood mortality: Not every child born survives to reach their own reproductive years.

• Sex ratio at birth: Naturally, slightly more boys are born than girls (about 105 boys to 100 girls), meaning women need to average slightly more than 2 children to replace themselves.

The effect of urbanization on birth rate

• Urbanization sharply decreases birth rates.

• Cities offer limited living space, higher costs of living, and less reliance on agricultural labor, removing the economic incentive for large families while expanding women's access to education and careers.

Reasons why the U.S. population is still increasing even with a low birth rate

• Net positive migration: Immigrants moving to the United States outpace emigration.

• Population momentum: The large generation of aging Millennials is still currently in or exiting their childbearing years, resulting in more total births than deaths despite a low fertility rate.

How urban density can affect carbon emissions

• Per capita emissions decrease: Dense cities pack residents closer together, resulting in lower per-person energy consumption compared to suburbs.

• Concentrated total emissions: While efficient on a per-person basis, the massive concentration of people and industry creates highly concentrated localized pollution hotspots.

Ways that cities can reduce their carbon footprints

• Expanding mass transit: Investing in trains, subways, and electric bus fleets.

• Enacting green building codes: Mandating energy-efficient insulation, solar readiness, and LED lighting.

• Zoning for mixed-use development: Placing residential, commercial, and retail zones together to eliminate the need for car trips.

• Transitioning to renewable grids: Powering municipal infrastructure with wind, solar, or nuclear energy.

How cities can harm human health

• Respiratory illnesses: Concentrated smog, particulate matter (\(PM_{2.5}\)), and industrial emissions trigger asthma and chronic lung conditions.

• Infectious disease spread: High population density facilitates the rapid transmission of viruses and bacteria.

• Mental health stressors: Noise pollution, overcrowding, and a lack of access to natural green spaces increase cortisol and anxiety.

Positive environmental effects of cities

• Land preservation: Concentrating millions of people into a small geographic footprint spares forests, wetlands, and agricultural land from development.

• Resource efficiency: Shared walls in apartment buildings reduce heating needs, and centralized utilities require less infrastructure per capita.

How urban sprawl can harm human health

• Physical inactivity: Automobile-dependent layouts eliminate walking, leading to higher rates of obesity, diabetes, and cardiovascular disease.

• Traffic accidents: Long commutes on high-speed arterial roads increase the frequency and severity of car crashes.

• Mental fatigue: Long daily commutes reduce sleep quality, increase stress, and cut into personal or family time.

Causes of urban sprawl

• Car-centric infrastructure: Decades of government investment in highways and roads rather than public transit.

• Cheap suburban land: Lower land costs outside the city center make large single-family homes affordable.

• Euclidean zoning regulations: Strict local laws that legally separate residential areas from commercial and retail areas.

The principles of smart growth

• Mix land uses: Place homes, offices, and shops in the same neighborhoods.

• Take advantage of compact design: Build upward rather than outward.

• Create walkable neighborhoods: Ensure pedestrian infrastructure is safe, continuous, and attractive.

• Foster distinctive, attractive communities: Preserve local culture, historic buildings, and natural beauty.

• Provide a variety of transportation choices: Integrate walking, biking, transit, and driving.

How smart growth can benefit the environment

• Reduces habitat fragmentation: Restricts expansion outward, saving native ecosystems.

• Lowers greenhouse gases: Minimizes vehicle miles traveled (VMT) by making walking and transit viable.

• Decreases runoff: Maximizes preserved natural ground to absorb rainwater.

Environmental benefits of mass transit

• Lower fuel consumption: Trains and buses move vastly more people per unit of fuel than single-occupancy vehicles.

• Reduced air pollution: Cuts down on localized smog, nitrogen oxides (\(NO_{x}\)), and particulate matter.

• Decreased land paving: Reduces the need for sprawling, impermeable multi-lane highways and parking lots.

Reasons for the urban heat island effect

• Albedo reduction: Dark surfaces like asphalt and roofs absorb solar radiation instead of reflecting it.

• Lack of evapotranspiration: Replacing trees and soil with concrete eliminates the natural cooling effect provided by plants releasing water vapor.

• Anthropogenic heat: Waste heat generated by cars, air conditioning units, and industrial facilities.

Ways to counteract the heat island effect

• Cool pavements: Using lighter-colored, reflective coatings on roads and parking lots.

• Urban forestry: Planting extensive street-tree canopies to shade sidewalks and buildings.

• Green roofs: Covering building tops with living vegetation to absorb heat and provide insulation.

Benefits of urban vegetation

Shades buildings, lowers local temperatures, filters air pollutants, and provides wildlife habitats.

Benefits of green roofs

Insulates buildings to cut energy costs, protects roofs from UV damage, and intercepts rainfall.

Benefits of rain gardens

Collects and absorbs neighborhood stormwater runoff, naturally filtering pollutants before they hit aquifers.

Methods to reduce urban runoff and flooding

• Permeable pavements: Installing porous concrete or interlocking pavers that allow rainwater to sink directly into the ground.

• Retention and detention ponds: Engineering dedicated basins to capture excess stormwater and release it slowly.

• Bioswales: Creating landscaped, vegetated ditches alongside roads to slow down and filter rushing rainwater.

Impact of urbanization on water supply

• Aquifer depletion: Impermeable concrete blocks rain from sinking into the ground, preventing groundwater reserves from recharging.

• Water quality degradation: Runoff sweeps motor oil, heavy metals, trash, and fertilizers directly into local streams and reservoirs.

• Altered stream hydrology: Heavy rain hits concrete and rushes into local waterways instantly, causing severe bank erosion and flash flooding rather than a slow, natural release.

Stages of the Demographic Transition Model (DTM):

Stage 1: High Stationary

• Birth Rate (BR) & Death Rate (DR): Both are very high and fluctuate due to disease and famine.

• Total Fertility Rate (TFR): High (lack of family planning, high infant mortality).

• Growth Rate (GR): Near zero or very low.

• Causes: Poor sanitation, lack of modern medicine, and reliance on subsistence agriculture (where children are needed for labor).

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Stages of the Demographic Transition Model (DTM)

Stage 2: Early Expanding

• Birth Rate (BR): Remains high.

• Death Rate (DR): Plummets rapidly.

• Total Fertility Rate (TFR): Remains high.

• Growth Rate (GR): Skyrockets (population explosion).

• Causes: Improvements in food supply, clean water, sanitation, and basic healthcare.

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Stages of the Demographic Transition Model (DTM)

Stage 3: Late Expanding

• Birth Rate (BR): Drops rapidly.

• Death Rate (DR): Continues to fall slowly.

• Total Fertility Rate (TFR): Decreases toward the replacement level (2.1).

• Growth Rate (GR): Slows down but remains positive.

• Causes: Urbanization, increasing female literacy/employment, and access to contraception.

Stages of the Demographic Transition Model (DTM)

Stage 4: Low Stationary

• Birth Rate (BR) & Death Rate (DR): Both are low and stabilize, pulling close together.

• Total Fertility Rate (TFR): Hovering at or just below replacement level.

• Growth Rate (GR): Near zero or stable.

• Causes: Highly developed economies, strong healthcare, and shifting cultural preferences toward smaller families.

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Stages of the Demographic Transition Model (DTM)

Stage 5: Declining (Theoretical/Emerging)

• Birth Rate (BR): Drops below the death rate.

• Death Rate (DR): Low but may rise slightly due to an aging population.

• Total Fertility Rate (TFR): Well below replacement level.

• Growth Rate (GR): Negative (population shrinks).

• Causes: Extreme costs of raising children, career prioritization, and an aging demographic (e.g., Japan, Germany).

Calculating doubling time (years)

70/ Growth Rate (%)/Rate of Natural Increase

How to calculate growth rate (%)

(Births +Immigration) - (Deaths+ Emigration)/Total x 100

How to calculate rate of natural increase (%)

Birth Rate-Death Rate/10

How to calculate population density

Total Population/ Land Area (in sq. miles or sq. km)

Analyzing Age Structure Diagrams (Population Pyramids)

Shape	Growth Type	DTM Stage	Characteristics
Wide Base / Triangle	Rapidly Growing	Stage 2	High birth rates, high youth dependency ratio, short life expectancy (e.g., Kenya).
Narrowing Base / Beehive	Slowly Growing	Stage 3 / 4	Birth rates are slowing down; population is stabilizing (e.g., USA).
Straight Sides / Column	Zero Growth	Stage 4	Births and deaths are balanced; even distribution across age groups (e.g., Sweden).
Inverted / Top-Heavy	Negative Growth	Stage 5	More old people than young people; shrinking workforce (e.g., Japan).