Impacts on human systems at HL: Climate-change impacts on human systems are taught identically for SL and HL. This is a natural fit for the HL economics focus — the costs fall unevenly, and someone has to pay.
No HL-only material to add — just learn how climate change affects human systems.
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Food and water security
Big idea: Climate change threatens food security and water security through changing rainfall, temperatures, and extreme events.
Impacts on agriculture
- Changed growing conditions: Some crops may fail; growing zones shift poleward
- Water stress: Drought reduces yields; changed monsoon patterns affect irrigation
- Extreme weather damage: Floods, storms, heatwaves destroy crops
- New pests and diseases: Warmer temperatures allow expansion to new areas
- Soil degradation: Increased erosion from intense rainfall; desertification
Impacts are uneven — some regions may benefit (longer growing seasons), but most will face challenges. LEDCs are often most vulnerable.
Water resources
- Glacier melt: Initially more water, then less as glaciers disappear
- Changed precipitation: Some regions drier, others wetter; more flooding
- Groundwater depletion: Increased demand during droughts
- Saltwater intrusion: Sea level rise contaminates coastal aquifers
- Water quality: Higher temperatures increase algal blooms
Exam tip: Essay questions often ask about impacts on societies. Structure your answer by sector: food, water, health, infrastructure, economy.
Know your predicted grade
Take timed mock exams and get detailed feedback on every answer. See exactly where you're losing marks.
Health, infrastructure and displacement
Big idea: Climate change affects human health directly (heat, disasters) and indirectly (disease, nutrition). It also threatens infrastructure and may force millions to relocate.
Health impacts
- Heat-related illness: Heatstroke, dehydration, cardiovascular stress
- Vector-borne diseases: Malaria, dengue expanding to new areas
- Waterborne diseases: Flooding spreads cholera, typhoid
- Air quality: Higher temperatures increase ground-level ozone; wildfire smoke
- Malnutrition: Reduced crop yields affect food availability
- Mental health: Climate anxiety, trauma from disasters, displacement stress
Infrastructure and displacement
- Coastal flooding: Threatens ports, cities, roads in low-lying areas
- Permafrost thaw: Damages buildings, roads, pipelines in Arctic regions
- Storm damage: More intense hurricanes/cyclones destroy infrastructure
- Climate refugees: People forced to move due to sea level rise, drought, or disasters
- Economic costs: Damage repair, lost productivity, insurance costs
Climate justice issue: Those who contributed least to climate change (LEDCs, small island nations) often face the worst impacts and have the fewest resources to adapt.
Exam tip: In discuss or evaluate questions, consider who is affected and discuss equity issues.
IB-style question — climate impacts on people [3]
A low-lying coastal country is preparing for the effects of climate change. Outline three ways climate change could affect its human population. [3]
How to answer it, step by step
- Pick different human systems
• Sea-level rise floods homes and displaces people (climate refugees)
• Saltwater ruins farmland, lowering food production - Vary the system you choose
• More storms/heatwaves damage infrastructure and harm health
• Or: damage to fishing/tourism hits the economy
Final answer
Spread your three points across different human systems (food, health, economy) — not three kinds of flooding.
IB-style question — to what extent are impacts shared equally [4]
"Climate change harms all countries equally." To what extent do you agree with this statement? [4]
How to answer it, step by step
- Some impacts are global
• Warming, sea-level rise and extreme weather reach every country
• No nation fully escapes the changing climate - Vulnerability differs — reach a verdict
• Poorer/low-lying nations are hit hardest yet emit least; rich nations can adapt
• So harm is not shared equally — impacts are real for all but unevenly felt
Final answer
For 'to what extent', give both sides and a clear judgement — a one-sided answer caps your marks.