Water vapour, carbon dioxide and methane are all described as greenhouse gases. State what is meant by the term 'greenhouse gases' and explain how an increase in the concentration of these gases in the atmosphere is linked to climate change.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Greenhouse gases are gases in the atmosphere that trap infra‑red radiation emitted by the Earth’s surface, keeping the planet warm enough for life.
An increase in the concentration of these gases means more infra‑red radiation is trapped and less escapes into space.
This raises the temperature of the Earth’s atmosphere, causing global warming.
The resulting change in global climate patterns is described as climate change.
An increase in the concentration of these gases means more infra‑red radiation is trapped and less escapes into space.
This raises the temperature of the Earth’s atmosphere, causing global warming.
The resulting change in global climate patterns is described as climate change.
Examiner tips
- Use the exact phrase ‘trap infra‑red radiation’ and link it to ‘maintain temperatures’.
- Show the causal chain: higher concentration → more trapping → higher temperature → climate change.
- Include all four points to reach full marks.
Common mistakes
- Confusing greenhouse gases with all atmospheric gases or omitting the infra‑red trapping mechanism.
- Failing to mention that the trapped radiation is emitted by the Earth’s surface, not the Sun.
- Using vague terms like ‘heat’ instead of ‘infra‑red radiation’ or ‘global warming’.”
Mark scheme (4 marks)
- Greenhouse gases are gases in the atmosphere that trap infra-red radiation (from the Earth's surface) / maintain temperatures on Earth high enough to support life
- A greater concentration of greenhouse gases means more infra-red radiation is trapped / less infra-red radiation escapes into space
- This causes the temperature of the Earth's atmosphere to increase / global warming
- This change in global climate patterns is described as climate change
Key terms in this question
greenhouse gases · climate change
Related
- All Pearson Edexcel International GCSE Chemistry (4CH1) revision notes →
- How to answer a "State and Explain" question →
- Decode the mark scheme abbreviations →
More Gases in the atmosphere questions
- Describe the natural greenhouse effect and explain why an increase in the concen…
- Methane and carbon dioxide are both described as greenhouse gases. Describe the …
- Nitrogen makes up approximately 78% of the Earth's atmosphere, yet it is not cla…
- Explain why the concentration of carbon dioxide in the Earth's atmosphere has in…