# Explain how the enhanced greenhouse effect leads to an increase in the average surface temperature of the Earth.

> IB DP Physics Standard Level (2023 syllabus) — B.2 Greenhouse effect · Explain · 4 marks

> Human activities have increased the concentration of greenhouse gases such as carbon dioxide and methane in the Earth's atmosphere since the Industrial Revolution.

## Mark scheme (4 marks)

1. Greenhouse gases absorb infrared radiation (emitted by the Earth's surface) rather than allowing it to escape to space.
2. The absorbed energy is re-emitted in all directions, including back towards the Earth's surface.
3. A higher concentration of greenhouse gases means more infrared radiation is absorbed and re-emitted, so more energy is returned to the surface (enhanced greenhouse effect).
4. The surface therefore receives more energy than it radiates away, so its temperature rises until a new equilibrium is reached at a higher temperature.

## Key terms

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

## Related

- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-enhanced-greenhouse-effect-7d32f0e1) · Published by Druglandscape Ltd.