Which statement correctly describes a positive feedback in climate systems, with a classic example?

• A. Negative feedback dampens responses; water vapor feedback is minimal
• B. Positive feedback dampens responses; cloud feedback is simple
• C. Positive feedback amplifies responses; ice-albedo feedback is a classic example
• D. Negative feedback amplifies climate responses; ozone formation is an example

Answer: (C)

Positive feedback in climate systems is when an initial change triggers processes that reinforce and magnify the original change. Ice-albedo feedback is a classic example: as temperatures rise and ice melts, surface albedo drops, meaning the surface absorbs more solar energy. That extra absorbed energy warms the surface further, causing more melting in a self-reinforcing loop. This is exactly what it means for the response to be amplified by the feedback.

So, describing positive feedback as amplifying responses and pointing to ice-albedo feedback as a well-known example correctly conveys the concept. The other statements mischaracterize the feedbacks: negative feedback would dampen changes, not amplify them, and water vapor is a strong positive feedback rather than minimal; cloud feedback is complex and not simply “simple”; and ozone formation isn’t a standard example of a negative feedback in the climate system.