Feedback Loops
A feedback loop happens when a change in a system causes effects that feed back into the system and cause more change.
Think of a feedback loop as a loop where the result becomes the cause.
Negative Feedback Loops (Stabilising)
A negative feedback loop reduces change and helps keep a system stable.
- Body temperature: too hot → sweating → body cools down
- Predator–prey populations: more prey → more predators → prey numbers fall
Negative does NOT mean bad. It means the system resists change and stays balanced.
Melting ice exposes darker surfaces that absorb more heat, causing even more melting
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Positive Feedback Loops (Amplifying)
A positive feedback loop makes the original change stronger and pushes the system further away from balance.
This happens because the effect of the change feeds back and causes even more of the same change.
Ice melt example (easy to picture)
- Ice melts due to warming
- Dark ocean or land underneath is exposed
- Dark surfaces absorb more heat than ice
- More heat causes even more ice to melt
Because melting ice leads to even more melting, this is a positive feedback loop.
Population example
- Population begins to decline
- Fewer individuals means fewer breeding pairs
- Fewer births occur
- Population declines faster
Positive does NOT mean good. It means the change is amplified.
One-sentence exam definition
A positive feedback loop occurs when a change in a system causes effects that increase the original change.
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