# Explain how the enhanced greenhouse effect leads to an increase in global average temperatures.

> IB DP Biology Standard Level (2023 syllabus) — D4.3 Climate change · Explain · 4 marks

> Atmospheric concentrations of greenhouse gases such as carbon dioxide and methane have increased significantly since industrialisation, altering Earth's energy balance.

## Mark scheme (4 marks)

1. Greenhouse gases absorb outgoing long-wave (infrared) radiation from Earth's surface
2. This absorbed energy is re-emitted in all directions, including back towards Earth's surface
3. Increased concentrations of greenhouse gases due to human activities (e.g. combustion of fossil fuels, deforestation) enhance this effect
4. The net result is that more energy is retained in the Earth's atmosphere/surface, raising global average temperatures

## Key terms

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

## Related

- [Revision notes for IB DP Biology 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-fc6e7d25) · Published by Druglandscape Ltd.