Key Idea: Topic 2.2 is about the consequences of global climate change — what a warming planet actually does to the environment, to people's health, and to different groups unequally. It pulls together three ideas: 2.2.1 — physical & environmental impacts: sea-level rise, melting ice and falling albedo, shifting biomes and more extreme weather reshape natural systems. 2.2.2 — impacts on people & health: heat stress, spreading disease, dirtier water and food, worse air and forced migration harm human wellbeing. 2.2.3 — vulnerability & uneven impacts: the harm is unequal — vulnerability = exposure + low adaptive capacity, driven by human factors (wealth, location, governance, gender), so the poorest suffer most. This is core content, examined on Paper 2 — a data-response read off a climate map, graph or infographic, a short structured Explain/Suggest, and a [10] 'to what extent' extended-response essay.
🌍 2.2.1 — Physical & environmental impacts
Warming reshapes environmental systems, not just people. For each impact, name it, then give the mechanism — the chain of cause and effect. The data skill examiners test is reading a temperature-anomaly map, a biome-shift map, or a line graph of flood events, then describing the trend with quoted figures.
Physical impacts and their mechanisms
| Impact | Mechanism (why it happens) |
|---|---|
| Sea-level rise | Warm ocean water expands (thermal expansion) + melting land ice adds water |
| Falling albedo | Bright ice melts and exposes dark ocean/land that absorbs more heat — a positive feedback |
| Shifting biomes | Temperature belts move polewards/uphill, so the climate a biome or species needs moves too |
| More extreme weather | A warmer atmosphere holds more energy and moisture, fuelling stronger heatwaves, droughts and storms |
Tip: For a map/graph question, describe the pattern first — name the highest and lowest values, quote a figure with units, and note any clustering. Then explain it with a mechanism (e.g. warm water expands → sea rises).
🤒 2.2.2 — Impacts on people & health
Warming threatens human health and wellbeing directly and indirectly. Explain needs a chain, not a label: hotter air → mosquitoes survive higher up → malaria spreads to new people.
Health hazards from a warming climate
| Health hazard | How warming causes it |
|---|---|
| Heat stress | Hotter days and heatwaves cause heatstroke, dehydration and heart strain — often fatal for the elderly |
| Spreading disease | Warmth lets mosquitoes survive in once-cool areas, carrying malaria and dengue to new populations |
| Water & food insecurity | Heat speeds bacterial growth (dirtier water); droughts cut harvests, raising malnutrition |
| Displacement & mental health | Floods and droughts force families to move, bringing stress and lost livelihoods |
Climate change forces some people to move, but it is usually one push factor among many — jobs, wages, war and family often matter more, and many move only short distances within their own country.
⚖️ 2.2.3 — Vulnerability & uneven impacts
The same hazard harms some people far more than others. Vulnerability = exposure + low adaptive capacity, and it is set mostly by human factors, not the physical event.
Why the impacts are uneven
| Human factor | Raises vulnerability | Lowers vulnerability (wealth) |
|---|---|---|
| Income & savings | No insurance or money to rebuild — a shock becomes a crisis | Can pay to defend, insure, relocate and recover |
| Where people live | The poor are pushed onto flood plains, slopes and dry margins | Wealth buys safer land away from the hazard |
| Governance | Little money for defences, warnings or emergency services | Strong sea walls, drainage and early-warning systems |
| Gender / age / health | Women, children, the elderly and sick have fewer resources, less mobility | Better access to help, healthcare and information |
Key terms to use precisely
- Sea-level rise — the rise in average ocean height from thermal expansion + melting land ice.
- Albedo — how much sunlight a surface reflects; bright ice = high, dark ocean/land = low.
- Biome — a large natural region defined by its climate, plants and animals.
- Heat stress — the body overheating, causing heatstroke, dehydration and heart strain.
- Vector-borne disease — illness spread by an animal carrier, e.g. malaria via mosquitoes.
- Climate migrant — a person forced to move because climate change makes home unlivable.
- Vulnerability — how likely a group is to be harmed by a hazard, and how badly.
- Exposure — whether people are physically in the path of the hazard.
- Adaptive capacity — the ability to prepare for, cope with and recover from impacts.
A group is most vulnerable when it is highly exposed to a hazard and has low adaptive capacity to cope. Wealth usually raises capacity — so poorer people are often more vulnerable even to the same hazard. Contrast a poor place (Bangladesh, the Sahel) with a protected one (the Netherlands) to prove it.
✍️ IB-style questions
Explain two ways in which higher temperatures could increase health hazards for people.
🔒 Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Examine the view that the impacts of global climate change are spread unevenly across the world.
🔒 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 do sea levels rise as the planet warms? Two mechanisms: thermal expansion (warm water expands) and melting land ice (glaciers and ice sheets add water).
What is albedo, and why does melting ice matter? Albedo is how much sunlight a surface reflects. Melting bright ice exposes dark ocean/land that absorbs more heat — a positive feedback that speeds warming.
Name two distinct health hazards from climate change. For example heat stress (heatstroke, dehydration) and spreading disease (mosquitoes carry malaria to new areas) — also water/food insecurity and displacement.
What is vulnerability, and what sets it? How likely a group is to be harmed by a hazard — set by exposure (in the hazard's path) plus adaptive capacity (ability to cope).
Why are poorer groups usually more vulnerable? They have less wealth, weaker defences and riskier locations, so the same flood or drought causes deeper, lasting harm and they recover slowly.
🎯 Highest-yield exam reminders
Exam tips
- Keep the three strands separate: physical/environmental (2.2.1), human health (2.2.2), uneven/vulnerability (2.2.3) — examiners penalise mixing them.
- Explain = give the MECHANISM (warm water expands → sea rises; hotter air → mosquitoes survive → malaria spreads), never just name it.
- Albedo: bright ice = high albedo; melting it exposes dark surface = a positive feedback loop.
- Data: Identify = read it off; Describe/Outline = state the trend AND quote figures with units (+38%, 6.5% of GDP).
- Vulnerability = exposure + low adaptive capacity — quote both; Suggest HUMAN factors (poverty, location, governance, gender), not physical ones.
- On the [10] 'to what extent' / Examine, weigh both sides with NAMED places (Bangladesh, Netherlands, small island states) and finish with a clear, justified judgement.