CoachA climate feedback is a change in the climate system, caused by a change in temperature, that alters the energy budget and so the temperature change itself. A positive feedback amplifies the initial change; a negative feedback damps it.
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Example 28.13 (Three feedbacks)
- Water vapour (positive). Warmer air holds more water vapour, a greenhouse gas, which adds to the warming.
- Snow and ice (positive). Snow and ice reflect sunlight; when they melt, the darker land and sea beneath absorb more of it, and the warming grows.
- Radiation to space (negative). A warmer surface and atmosphere radiate more infrared to space. This basic response always wins in the end: it is why the climate settles at a new, warmer balance instead of warming without limit.