Cambridge O Level Environmental Management: The Atmosphere and Human Activities — Revision Notes (5014, 2027-2029)

Syllabus edition note. These notes follow the Cambridge O Level Environmental Management 5014 syllabus for exams in 2027, 2028 and 2029.

Topic 4 of Cambridge O Level Environmental Management (5014) is about three ways human activity changes the atmosphere: climate change, acid rain and ozone depletion. For each one you need the same chain - cause → process → impacts → strategies → benefits and limitations - plus some basic facts about the atmosphere itself. Learning the chain once and reusing it for each problem is the fastest way to revise.

Full explanations: atmosphere study guide. Test yourself: atmosphere practice questions.

Syllabus coverage (5014, 2027-2029)

Sub-topic	Outcomes	In one line
4.1 The atmosphere	4.1.1-4.1.3	Four layers, composition, climate, natural greenhouse effect
4.2 Climate change	4.2.1-4.2.9	Greenhouse gases, six causes, twelve impacts, twelve footprint strategies, four adaptations
4.3 Acid rain	4.3.1-4.3.4	SO2 and NOx, six impacts, three strategies
4.4 Ozone depletion	4.4.1-4.4.4	CFCs, three impacts, three strategies

4.1 Atmosphere quick facts

• Layers, lowest first: troposphere, stratosphere, mesosphere, thermosphere.
• Ozone layer: lower stratosphere.
• Clean air: 78% nitrogen, 21% oxygen; carbon dioxide, argon and water vapour make up the rest.
• Climate: weather conditions in a location based on the weather over many years.
• Natural greenhouse effect: solar radiation passes through the atmosphere → some is absorbed by land and oceans → some is reflected to space → some is absorbed and re-emitted to the surface by greenhouse gases and clouds → the Earth stays warm enough for life.

4.2 Climate change chain

Cause. Greenhouse gas = absorbs radiation and emits the energy as thermal energy. Named gases: CO2, H2O, CH4.

Source	Greenhouse gas
Fossil fuel combustion	CO2
Cattle digestion, manure, rice fields	CH4
Deforestation (less photosynthesis)	CO2 stays in the air
Draining wetlands	CH4
Cement: limestone heated to lime	CO2
Population growth and energy use	CO2

Process. More greenhouse gases absorb more radiation → enhanced greenhouse effect → global warming → climate change.

Impacts - remember three groups.

• Physical: hotter land and ocean surface; melting ice sheets, glaciers and permafrost; sea-level rise; ocean acidification; more extreme weather (floods, loss of land, drought, wildfires).
• Living things: disrupted food chains; biodiversity change; habitat loss; more pests and invasive species; forced migration of animals.
• People: forced migration; changed crop yields; food shortages.

Strategies to reduce carbon footprints - remember three groups.

• Energy and transport: less fossil fuel; energy efficiency; transport policies; carbon sequestration (capture, remove, store CO2).
• Food and land: plant-based, seasonal and local food; less livestock; reforestation and afforestation; fewer children per woman.
• Government and science: international agreements and policies; taxation; research and climate models; artificial intelligence to predict impacts and develop strategies.

Adaptation = altering behaviour, practices and infrastructure to adapt to climate change impacts: resistant crops; flood defences; laws on building near coasts and floodplains; building design and materials.

Benefits vs limitations (4.2.9) - a general pattern you can apply

• Global strategies (agreements, taxation) can cut emissions at scale but are hard to agree and enforce.
• Individual strategies (diet, energy saving) are cheap and immediate but small unless many people act.
• Technology (sequestration, AI, models) can be powerful but is costly and depends on data and investment.
• Adaptation protects people now but does not reduce the cause.

4.3 Acid rain chain

• Cause: SO2 from burning sulfur-containing fossil fuels and from volcanoes; oxides of nitrogen from nitrogen and oxygen reacting in hot vehicle engines.
• Process: these gases react with oxygen and water vapour in the atmosphere → acid rain.
• Impacts: acid lakes and rivers; fewer fish; damaged aquatic food webs; acid soils; defoliation and lower crop yields; damaged buildings.
• Strategies: flue-gas desulfurisation (SO2 reacts with calcium carbonate or calcium oxide); catalytic converters (remove NOx); transport policies.
• Limitations: desulfurisation is expensive and needs limestone; converters do nothing about SO2 from power stations; acid rain can fall in a different country from the source, so cooperation is needed.

4.4 Ozone depletion chain

• Cause: CFCs from aerosols and refrigerants destroy ozone in the ozone layer.
• Impacts: more solar radiation at the surface; more cancer and cataracts; damaged vegetation and lower crop yields.
• Strategies: international agreement and policies (Montreal Protocol, 1987); CFC ban and alternatives; safe disposal of CFCs.
• Benefit: global action reduced CFC production sharply. Limitation: CFCs remain in the atmosphere for decades, and old equipment still contains them.

Worked example: comparing two strategies

A government must choose between a carbon tax and a tree-planting scheme.

Criterion	Carbon tax	Afforestation
Speed of effect	Fast - prices change behaviour at once	Slow - trees take years to grow
Cost to government	Raises money	Costs money and land
Fairness	Can hit low-income households	Can create rural jobs
Extra benefits	Funds renewable energy	Habitats, soil protection, flood control

Judgement: the tax works faster; afforestation gives wider environmental benefits. Using both is strongest.

Common mistakes and exam traps

• Saying “the greenhouse effect is bad”: the natural effect supports life; the problem is the enhanced effect.
• Linking CFCs to global warming in answers about ozone depletion.
• Saying acid rain comes from carbon dioxide: the syllabus names sulfur dioxide and oxides of nitrogen.
• Treating adaptation as a way to reduce emissions.
• Ignoring the command word: “describe” for strategies, “discuss” for benefits and limitations.

Frequently asked questions

What are the three greenhouse gases named in 5014? Carbon dioxide, water vapour and methane.

How does cement manufacture cause climate change? Limestone (calcium carbonate) is heated to make lime (calcium oxide), which releases carbon dioxide.

Why is the Montreal Protocol seen as a success? Countries agreed to phase out CFCs and alternatives were available, so production fell sharply, although the ozone layer takes decades to recover.

Official syllabus

Cambridge O Level Environmental Management (5014) syllabus for 2027, 2028 and 2029 - official syllabus PDF, Topic 4.