# Explain how positive feedback mechanisms in the Arctic contribute to accelerating global warming.

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

> Permafrost covers approximately 25% of the Northern Hemisphere's land surface and contains large quantities of organic carbon accumulated over thousands of years. As global temperatures rise, this permafrost begins to thaw.

## Mark scheme (4 marks)

1. Melting of Arctic sea ice / snow reduces albedo (reflectivity) of the Earth's surface
2. Increased absorption of solar energy by exposed ocean / land causes further warming, reinforcing the initial temperature rise
3. Thawing permafrost releases stored carbon as carbon dioxide and/or methane through decomposition by microorganisms
4. Released greenhouse gases enhance the greenhouse effect, causing further warming which in turn drives more permafrost thaw / ice melt, completing the positive feedback loop

## Key terms

- [positive feedback](https://www.gradenine.co.uk/glossary/positive-feedback)

## Related

- [Revision notes for IB DP Biology Higher 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-positive-feedback-mechanisms-in-fad4f852) · Published by Druglandscape Ltd.