Describe how the combustion of fossil fuels in vehicles contributes to the greenhouse effect and leads to climate change.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Combustion of fossil fuels in vehicles releases carbon dioxide and water vapour into the atmosphere.
Carbon dioxide is a greenhouse gas that absorbs infrared radiation emitted by the Earth’s surface.
The absorbed energy is re‑emitted back towards the Earth, trapping heat and preventing it from escaping into space.
An increased concentration of CO₂ enhances the greenhouse effect, causing global warming and climate change such as rising sea levels and more extreme weather.
Carbon dioxide is a greenhouse gas that absorbs infrared radiation emitted by the Earth’s surface.
The absorbed energy is re‑emitted back towards the Earth, trapping heat and preventing it from escaping into space.
An increased concentration of CO₂ enhances the greenhouse effect, causing global warming and climate change such as rising sea levels and more extreme weather.
Examiner tips
- Use the exact terminology: carbon dioxide, greenhouse gas, infrared radiation, re‑emitted, enhanced greenhouse effect.
- Show the causal chain: combustion → CO₂ → heat trapping → warming → climate change.
- Keep each point concise to fit the 4 marks.
Common mistakes
- Mixing up CO₂ with other gases like methane; only CO₂ is required here.
- Failing to mention the re‑emission of heat back to Earth; only absorption is not enough.
Mark scheme (4 marks)
- Combustion of fossil fuels produces carbon dioxide (and water vapour)
- Carbon dioxide is a greenhouse gas that absorbs / traps heat (infrared radiation) from the Earth's surface
- The absorbed energy is re-emitted back towards the Earth, warming the atmosphere / preventing heat from escaping into space
- Increased concentration of greenhouse gases causes enhanced greenhouse effect, leading to global warming / climate change (e.g. rising sea levels, more extreme weather)
Key terms in this question
combustion · greenhouse effect · climate change
Related
- All Cambridge International IGCSE Chemistry (0620) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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