# Methane and carbon dioxide are both described as greenhouse gases. Describe the greenhouse effect and explain why greenhouse gases are necessary for life on Earth.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 2.3 Gases in the atmosphere · Describe · 4 marks

## Mark scheme (4 marks)

1. Greenhouse gases trap infra-red radiation (from the Earth's surface)
2. This causes an increase in the temperature of the Earth's atmosphere
3. Without greenhouse gases temperatures on Earth would be too low / the Earth would be too cold
4. Greenhouse gases maintain temperatures on Earth high enough to support life (allowing liquid water / biological processes to exist)

## Key terms

- [greenhouse effect](https://www.gradenine.co.uk/glossary/greenhouse-effect)
- [greenhouse gases](https://www.gradenine.co.uk/glossary/greenhouse-gases)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/methane-and-carbon-dioxide-are-both-69b8958c) · Published by Druglandscape Ltd.