Describe how deforestation can contribute to global warming.

Pearson Edexcel International GCSE Biology (4BI1) — 4.1 The organism in the environment · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Large areas of tropical forest are cleared each year to provide land for cattle farming and crop production. Scientists have linked this activity to rising average temperatures across the Earth.

Model answer (4 marks)

1. Deforestation removes trees and plants that normally absorb CO₂ during photosynthesis.
2. With fewer trees, less CO₂ is taken out of the atmosphere.
3. The felled trees are often burned or decompose, releasing CO₂ back into the air.
4. CO₂ is a greenhouse gas, so its increased concentration traps more heat and raises global temperatures.

Examiner tips

Use the exact wording from the mark scheme (e.g., ‘photosynthesis’, ‘carbon dioxide’, ‘greenhouse gas’).
Show the causal chain: removal → less uptake → more release → warming.
Keep each point short and to the point – 1–2 sentences per mark.

Common mistakes

Confusing deforestation with forest degradation or mentioning only one effect (e.g., only CO₂ release).
Using vague terms like ‘climate change’ instead of ‘global warming’ or omitting the greenhouse gas mechanism.

Mark scheme (4 marks)

Deforestation reduces the number of trees / plants available for photosynthesis
So less carbon dioxide is removed from the atmosphere
Burning / decomposition of felled trees releases carbon dioxide into the atmosphere
Carbon dioxide is a greenhouse gas that traps heat / raises the Earth's average temperature

Key terms in this question

deforestation · global warming