AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Levels of carbon dioxide and methane in the atmosphere are increasing, and…
Full specification wording
Global warming: Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’.
Carbon dioxide and methane are greenhouse gases.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 2 of 2
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Carbon dioxide and methane are greenhouse gases. 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.
What earns the marks
- 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.
- The rise in average global temperature is called global warming.
Common mistakes and how to put them right
Thinking the greenhouse effect is entirely harmful.
Put it right: A natural greenhouse effect keeps Earth warm enough for life, but extra gases strengthen it.
Confusing global warming with ozone depletion.
Put it right: They are separate processes caused by different gases.
Believing carbon dioxide is the only greenhouse gas.
Put it right: Methane is also a greenhouse gas and its level is increasing.
Exam 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.
Try the lesson
The start of the Global warming: Levels of carbon dioxide and methane in the atmosphere are increasing, and contribute to ‘global warming’. lesson, made from checked teaching notes for this specification point.
Have a go first
Which two gases are increasing in the atmosphere and contributing to global warming?
Listen
Carbon dioxide and methane are greenhouse gases. 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. A strong answer earns marks for these 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. A common slip: Thinking the greenhouse effect is entirely harmful. Instead, a natural greenhouse effect keeps Earth warm enough for life, but extra gases strengthen it. Exam tip: Name both carbon dioxide and methane and give a source for each.
Key words
Say what each word means before you turn the card.
Greenhouse effect
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Global warming
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Carbon dioxide
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Methane
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See every definition
- Greenhouse effect
- Greenhouse gases absorb infrared radiation emitted by the Earth and re-radiate some of it back, so less heat escapes to space.
- Global warming
- The rise in average global temperature resulting from a strengthened greenhouse effect.
- Carbon dioxide
- A greenhouse gas released into the atmosphere by burning fossil fuels.
- Methane
- A greenhouse gas released by agriculture, landfill and fossil fuel extraction.
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