Positive feedback and tipping points
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Question
What is a positive feedback loop?
Answer
A loop where the **effect makes the original change even bigger** — it is **self-amplifying**.
Question
What is a negative feedback loop?
Answer
A loop where the **effect opposes the change**, returning the system **toward balance** (self-correcting).
Question
Does 'positive' feedback mean the effect is good?
Answer
**No.** 'Positive' means the change is **amplified** — a positive climate feedback loop is **harmful** (more warming).
Question
Trace the ice–albedo positive feedback loop.
Answer
Warming **melts bright ice** → exposes a **darker, lower-albedo surface** → it **absorbs more heat** → **more warming** → **more melting**.
Question
How does thawing permafrost amplify warming?
Answer
It **releases trapped methane and CO2** (greenhouse gases) → these **trap more heat** → more warming → **more thaw**.
Question
How does a warming ocean amplify warming?
Answer
Warm water **holds less dissolved CO2**, so CO2 is **released to the air**, trapping more heat → the ocean warms further.
Question
What is albedo?
Answer
How much sunlight a surface **reflects**. Bright ice = **high** albedo (reflects); dark sea/land = **low** albedo (absorbs).
Question
What is a tipping point?
Answer
A **threshold** past which change becomes **self-sustaining and irreversible** — runaway warming.
Question
Name three positive climate feedback loops.
Answer
**Ice–albedo**, **permafrost methane** release, and **ocean CO2 release**.
Question
How can you tell a process is positive feedback?
Answer
Finish the sentence: '…and that causes **MORE** warming.' If it adds to the change, it is **positive** feedback.
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Topic 4.12 hub
Climate change
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