Anthropogenic causes and the carbon cycle
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Question
What does 'anthropogenic' mean?
Answer
**Caused by human activity** (rather than by natural processes).
Question
Name the four main human activities that raise atmospheric CO₂.
Answer
**Burning fossil fuels**, **deforestation**, **agriculture**, and **cattle farming**. (Hook: FDAC.)
Question
Which human activity adds the MOST CO₂?
Answer
**Burning fossil fuels** — it releases carbon stored in coal, oil and gas for millions of years.
Question
What is a carbon sink vs a carbon source?
Answer
A **sink** removes CO₂ from the air (photosynthesis); a **source** adds CO₂ (respiration, decomposition, combustion).
Question
Why does deforestation count as a 'double hit'?
Answer
It **removes a sink** (fewer trees photosynthesising) AND **releases** the stored carbon when the wood is burnt or rots.
Question
Which action reduces carbon sequestration?
Answer
**Deforestation / clearing forest** — it stops trees locking carbon away by photosynthesis.
Question
How does cattle farming warm the climate?
Answer
Cattle release **methane** (a potent greenhouse gas) from digestion, and clearing forest for pasture **removes a sink** and releases CO₂.
Question
Why does atmospheric CO₂ rise each winter?
Answer
Most plants **stop photosynthesising**, but **respiration and decomposition continue**, so CO₂ is added faster than it is removed.
Question
On a CO₂ graph, what causes the long-term rise vs the yearly zig-zag?
Answer
Long-term **rise** = human activity (mainly fossil fuels); yearly **zig-zag** = photosynthesis (down in summer) vs respiration/decomposition (up in winter).
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