Global warming — AQA GCSE Biology
Test yourself on Global warming with AQA GCSE practice questions.
Start free
7 days Premium · Then free forever · No card, no charge
Global warming explained
Carbon dioxide and methane are greenhouse gases.
Read the full explanation
Their levels in the atmosphere are rising because of human activities: burning fossil fuels releases carbon dioxide, while agriculture, landfill and fossil fuel extraction release methane. Greenhouse gases absorb infrared radiation emitted by the Earth and re-radiate some of it back, so less heat escapes to space and the average global temperature rises. This is the greenhouse effect, and the resulting increase in temperature is called global warming. More carbon dioxide and methane therefore strengthen the greenhouse effect and contribute to global warming.
Your focus
- State that carbon dioxide and methane are greenhouse gases whose atmospheric levels are increasing.
- Describe how greenhouse gases absorb and re-radiate infrared radiation.
- Explain how increasing greenhouse gas levels contribute to global warming.
Global warming exam tips
Marking Points
- Carbon dioxide and methane are greenhouse gases.
- Burning fossil fuels releases carbon dioxide into the atmosphere.
- Agriculture, landfill and fossil fuel extraction release methane.
- Greenhouse gases absorb infrared radiation emitted by the Earth.
- Some of this radiation is re-radiated back towards the Earth, so less heat escapes.
- This strengthens the greenhouse effect and raises average global temperature.
- The rise in average global temperature is called global warming.
Examiner Tips
- 💡Name both carbon dioxide and methane and give a source for each.
- 💡Explain the greenhouse effect in steps: absorption, re-radiation, less heat escaping.
- 💡Use the phrase average global temperature rather than just saying the weather gets hotter.
Common Mistakes
- Thinking the greenhouse effect is entirely harmful; correction: a natural greenhouse effect keeps Earth warm enough for life, but extra gases strengthen it.
- Confusing global warming with ozone depletion; correction: they are separate processes caused by different gases.
- Believing carbon dioxide is the only greenhouse gas; correction: methane is also a greenhouse gas and its level is increasing.