Describe methane and carbon dioxide air pollution
Methane and carbon dioxide come from human activities including fuel use and agriculture; rising greenhouse-gas concentrations enhance the greenhouse effect and contribute to climate change.
Exam scope and assessment notes
Core and Extended · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Know that organisms interact with other organisms and their environment.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What is one syllabus-linked effect of increased methane and carbon dioxide in air?
What you will learn
- Describe sources of methane and carbon dioxide air pollution
- Explain the enhanced greenhouse effect and link it with climate change
Identify human sources of greenhouse gases
Burning fossil fuels in transport, electricity generation and industry releases carbon dioxide. Deforestation can also increase atmospheric carbon dioxide because less is removed by photosynthesis and stored carbon may be released.
Methane is released from some agricultural activities, including digestion in ruminant livestock, and from decomposition of organic waste in low-oxygen conditions. Fossil-fuel extraction and distribution can also release methane.
Explain the enhanced greenhouse effect
Greenhouse gases absorb some outgoing infrared radiation and re-emit it, slowing energy loss from Earth’s atmosphere. Higher concentrations of methane and carbon dioxide strengthen this greenhouse effect, raising average global temperature and contributing to climate change.
Climate change includes long-term shifts in temperature and weather patterns. Avoid saying greenhouse gases trap all heat or that one weather event alone proves climate change. The syllabus limit is the enhanced greenhouse effect and climate change.
Pause and explain
Which activity is a source of carbon dioxide pollution?
Worked example
A region burns more fossil fuel and clears forest. Explain how these changes can raise atmospheric carbon dioxide and affect climate.
Show the worked solution
- Combustion releases carbon dioxide.
- Forest clearance reduces removal and may release stored carbon.
Answer Burning fossil fuel releases carbon dioxide; clearing forest reduces carbon uptake and can release stored carbon. Higher carbon dioxide concentration enhances the greenhouse effect and contributes to climate change.
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Name one source each of carbon dioxide and methane pollution.
Give me a hint
Use a human activity for each gas.
Compare my reasoning
- Fossil-fuel combustion releases carbon dioxide.
- Ruminant digestion or anaerobic decomposition can release methane.
Fossil-fuel combustion is a source of carbon dioxide. Methane can be released by ruminant livestock or decomposition of organic waste in low-oxygen conditions.
Look for these in your work
- Both gases named
- Sources matched
Explain how increased greenhouse-gas concentration contributes to climate change.
Give me a hint
Connect infrared radiation, enhanced greenhouse effect and warming.
Compare my reasoning
- Greenhouse gases absorb and re-emit some outgoing infrared radiation.
- Higher concentrations slow energy loss and raise average global temperature.
Higher concentrations of methane and carbon dioxide enhance the greenhouse effect by absorbing and re-emitting more outgoing infrared radiation. This raises average global temperature and contributes to climate change.
Look for these in your work
- Mechanism described
- Climate link stated
A student says a cold winter disproves climate change. Explain why the claim is not supported.
Give me a hint
Distinguish a local or short-term event from long-term climate patterns.
Compare my reasoning
- Weather varies over short periods and places.
- Climate change refers to long-term shifts in climate patterns.
A cold winter is a short-term weather event. Climate change concerns long-term shifts in temperature and weather patterns, so one season does not by itself disprove the trend.
Look for these in your work
- Weather and climate distinguished
- Evidence scope clarified
Common mistakes
- Confusing the natural greenhouse effect with its enhancement
- Claiming carbon dioxide is the only greenhouse gas
- Treating a single storm as proof of climate change
What can you explain now?
What is one syllabus-linked effect of increased methane and carbon dioxide in air?
Compare with the explanation
An enhanced greenhouse effect that contributes to climate change
This matches the stated limit.
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Make it stick
Name sources of methane and carbon dioxide and explain the enhanced greenhouse effect.
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