Key Idea: Topic 13.3 is about the stresses a growing city puts on its environment and its people. It pulls together two strands: 13.3.1 — environmental stresses: crowding people, traffic and concrete into a small space creates the urban heat island, air pollution and loss of green space — human activity reshaping the city's microclimate. 13.3.2 — social stresses & deprivation: concentrated lack of work, income, housing, health, education and safety — measured with deprivation indicators, explained by the cycle of deprivation, and clustered on the least desirable land. Urban environments is an Option (G), examined on Paper 1: a short data-response / structured question off a figure, then a [10] extended-answer (Examine / Evaluate / Discuss) marked on markbands. SL answers two options, HL three — same questions at both levels.
🏙️ 13.3.1 — Environmental stresses & the microclimate
Fast urban growth packs traffic, industry and hard surfaces into a small area, stressing the local environment. The classic stimulus is a temperature transect running from the rural edge, across the dense centre, and out to the rural edge again — the warm dome over the centre is the urban heat island. The skill examiners test is reading a value off the figure (State / Estimate), then explaining how human activity warms and dirties the city, before weighing strategies that try to cut the stress.
Read the y-axis first: where is the line highest (warmest), and how big is the centre-to-edge gap (~8 °C)?
🔒 Interactive diagram
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Environmental stresses — cause and effect
| Stress | What causes it | What it does to the city |
|---|---|---|
| Urban heat island | Low-albedo concrete + tarmac, waste heat, fewer plants, tall buildings | City runs several °C warmer than the countryside, worst at night |
| Air pollution | Vehicle and factory emissions, coal heating | A pollution dome of harmful particles/gases harms health and traps heat |
| Microclimate change | Hard surfaces, street canyons, waste heat | Hotter, gustier, dirtier local climate than the surrounding land |
| Loss of green space | High land values → parks built over for profit; weak planning | Removes natural cooling, water storage and clean air |
Key terms — environmental stress
- Urban heat island (UHI) — a city being warmer than the rural land around it, especially at night.
- Urban microclimate — the city's own local climate (temperature, wind, rainfall), changed by buildings and activity.
- Albedo — how much sunlight a surface reflects; dark concrete/tarmac have low albedo, so they absorb and store heat.
- Air pollution — harmful gases and particles (traffic, industry) building up in a pollution dome over the city.
- Green space — parks, gardens, trees and verges that cool the city, clean the air and store water.
Tip: For a transect/graph question, read the figure first — a centre value, a rural value, the gap between them (e.g. ~26 °C vs ~18 °C = an ~8 °C heat island). Then explain with a cause → effect chain: more concrete and traffic → warmer, dirtier air → harm to people and nature. Name the link, don't just name the problem.
🧱 13.3.2 — Social stresses & deprivation
Cities also face social stresses. Urban social deprivation is concentrated lack of work, income, housing, health, education and safety. It is multiple (the problems overlap) and clustered (it concentrates in particular neighbourhoods), so cities show sharp rich/poor contrasts. It is measured with deprivation indicators, its persistence explained by the cycle of deprivation, and its location set by physical, economic and political factors that push the poor onto the least desirable land.
How deprivation works — measure, persistence, location
| Idea | What it means | Why it matters in the exam |
|---|---|---|
| Deprivation indicators | Unemployment, low income, poor health, overcrowding, low qualifications, high crime | Read worst/best area off a bar chart or table; quote the figure |
| Multiple deprivation | Several problems occurring together in the same place | Indicators move together — worst in inner old-industrial / social-housing areas |
| Cycle of deprivation | Few jobs → low income → poor housing/health → few qualifications → low skills → still no jobs | A self-reinforcing loop that traps an area for generations |
| Location factors | Physical (steep, marshy, polluted land), economic (cheap rents), political (zoning) | The poor get the least desirable, cheapest land; CBD distance is economic |
Key terms — social stress & deprivation
- Social deprivation — lacking the resources and opportunities most people have (work, income, health, education).
- Multiple deprivation — several of these problems occurring together, reinforcing one another.
- Cycle of deprivation — a self-reinforcing loop where poverty causes poor outcomes that cause more poverty.
- Deprivation indicators — measures used to map it (unemployment, overcrowding, low qualifications, crime).
- Stakeholders — the groups with an interest in the area: residents, government, police, businesses, community groups.
If an Outline asks for a physical factor locating low-income housing, give a physical site feature — steep slope, marshy/flood-prone or contaminated land (e.g. hillside favelas in Rio, lagoon-edge settlement in Lagos). Distance from the CBD is an economic factor and scores nothing here. Name the feature, then develop why it pushes the poor there (cheap, hazardous, undesirable land).
✍️ IB-style questions
Explain one environmental benefit and one separate social benefit of reducing traffic in a city.
🔒 Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Examine how successfully strategies have reduced environmental or social stresses in one or more named urban areas.
🔒 Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
✅ Quick self-check
Tap each card to reveal the answer.
Why is a city warmer than the countryside around it? The urban heat island: low-albedo concrete/tarmac absorb heat by day and release it at night, tall buildings trap it, there is less cooling vegetation, and traffic and industry add waste heat.
Name two ways human activity changes the urban microclimate. Hard surfaces (concrete/tarmac lower albedo, raising temperatures) and emissions (vehicle/factory fumes thicken the pollution dome and trap heat). Tall buildings and waste heat also count.
What is the cycle of deprivation? A self-reinforcing loop: few jobs → low income → poor housing/health → few qualifications → low skills + no investment → still no jobs. Each stage feeds the next, trapping the area.
Why does deprivation locate where it does? The poor get the least desirable land (steep, marshy, polluted) and the cheapest housing, reinforced by planning and political decisions. Distance from the CBD is an economic factor, not physical.
What does a top [10] Examine answer need? Two or more strategies/factors developed with a named city and data, a weighing of how successful each is (limits, stakeholders, places), and a clear, justified judgement.
🎯 Highest-yield exam reminders
Exam Tips
- Data-response: read the figure FIRST and quote it (a temperature, a percentage, a grid square) — vague description without numbers loses the data mark.
- Urban heat island = city warmer than rural; always give the CAUSE (low albedo, waste heat) AND develop it to a warmer city.
- Explain = effect + development; keep environmental and social benefits separate (3 + 3) — the same point can't score twice.
- Deprivation is MULTIPLE (jobs, income, housing, health, schools, crime overlap) and CLUSTERED; the cycle traps the area.
- Outline a PHYSICAL site factor (steep/marshy/polluted) — distance from the CBD is economic and scores nothing.
- On the [10] Examine/Evaluate: 2+ strategies/factors + a NAMED city + how successful (and for whom) + a justified judgement.