# Scientists have recorded a significant decrease in Arctic sea ice over the past 50 years. Explain how human activities have led to this decrease in Arctic sea ice.

> Pearson Edexcel A-Level Biology A (9BI0) — 3.3 Climate change · Explain · 5 marks

> Arctic sea ice extent has declined by approximately 13% per decade since satellite records began. Scientists link this decline to rising global temperatures caused by human activities.

## Mark scheme (5 marks)

1. Human activities (such as burning fossil fuels / deforestation) release carbon dioxide (and other greenhouse gases) into the atmosphere
2. Increased levels of greenhouse gases in the atmosphere trap / absorb more heat (infrared radiation) from the Earth's surface
3. This leads to an increase in global temperature / global warming
4. Higher temperatures cause Arctic sea ice to melt / the rate of melting exceeds the rate of ice formation
5. Melting of sea ice reduces the reflectivity (albedo) of the Arctic surface, causing further warming and further ice loss (positive feedback)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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