Explain why the concentration of carbon dioxide in the Earth's atmosphere has increased since the Industrial Revolution, and describe how this increase contributes to climate change.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Carbon dioxide is one of several greenhouse gases found in the Earth's atmosphere. Since the Industrial Revolution, its concentration has risen significantly.
Model answer (4 marks)
The concentration of CO₂ has risen because the combustion of fossil fuels (coal, oil and gas) has increased during the Industrial Revolution, releasing large amounts of CO₂ into the atmosphere. At the same time, deforestation and land‑use changes mean fewer trees and plants are available to absorb CO₂ through photosynthesis, so less CO₂ is removed from the air. CO₂ is a greenhouse gas; it absorbs infra‑red radiation emitted by the Earth’s surface and re‑radiates it back, trapping heat. The enhanced greenhouse effect raises the average temperature of the atmosphere, which drives the observed changes in climate.
Examiner tips
- Use the exact phrases: ‘combustion of fossil fuels’, ‘deforestation’, ‘greenhouse gas’, ‘traps infra‑red radiation’, ‘increase in temperature’, ‘climate change’. Show the causal chain clearly and keep each point brief. Include the word ‘traps’ to link CO₂ to the greenhouse effect.
Common mistakes
- Mixing up the direction of heat transfer (e.g. saying CO₂ releases heat rather than trapping it). Forgetting to mention deforestation or the role of photosynthesis. Using vague terms like ‘more CO₂’ without explaining the source or effect.
Mark scheme (4 marks)
- Increased combustion of fossil fuels releases carbon dioxide into the atmosphere
- Increased deforestation means fewer trees/plants to remove carbon dioxide by photosynthesis
- Carbon dioxide is a greenhouse gas that traps infra-red radiation from the Earth's surface
- This leads to an increase in the temperature of the Earth's atmosphere, causing climate change
Key terms in this question
Related
- All Pearson Edexcel International GCSE Chemistry (4CH1) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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