Example 1
Warming melts bright sea ice and exposes dark ocean. Classify the feedback.
Less reflection increases absorbed solar energy, tending to cause more warming. Because it amplifies the initial change, it is positive feedback.
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Year 10
Oceans, ice and climate feedbacks
Trace energy and matter interactions among Earth’s spheres and classify feedback direction.
Method and worked examples
The atmosphere exchanges energy with oceans, land and living systems. Oceans absorb and store large quantities of energy, influencing how quickly surface temperatures respond. Currents redistribute energy, while evaporation and condensation transfer energy between ocean and air. Carbon exchange between atmosphere, biosphere, ocean and geological reservoirs links climate with the carbon cycle. A climate model must include these interacting stores.
A feedback is a response that alters the initial change. Ice loss exposes darker surfaces that reflect less sunlight, increasing absorption and tending to amplify warming: a positive feedback. More outgoing infrared from a warmer Earth tends to oppose warming: negative feedback. “Positive” means amplifying, not beneficial. Warmer air can contain more water vapour, strengthening greenhouse warming; this does not make water vapour the independent cause of every initial change.
Example 1
Example 2
Why can ocean warming continue even while the atmosphere varies from year to year?
The ocean stores large amounts of energy and exchanges it over time. Short-term atmospheric variation does not by itself erase a longer-term energy gain.
Watch out: Positive feedback amplifies a change. The term describes direction, not whether the outcome is good.