Climate feedback
A process triggered by a climate change that then strengthens or weakens the original response.
Example
Melting sea ice exposes darker water, which absorbs more sunlight and can amplify warming.
The catch
Feedback strength and timing vary between physical processes.
Related terms
Climate change, Albedo, Atmospheric lifetime, Carbon budget, Carbon dioxide, Climate model
In more depth
Climate feedback, explained.
Climate feedbacks set how much warming a given rise in greenhouse gases produces, and they are the main reason estimates of climate sensitivity span a range. Warmer air holds more water vapour, itself a greenhouse gas, which makes water vapour the strongest amplifying feedback. A warmer planet also radiates more heat to space, the basic stabilising response. Clouds contribute the largest uncertainty in the total.
In this field, 'positive' means amplifying, so a positive feedback makes warming worse. Carbon-cycle feedbacks add another layer. Thawing permafrost and warmer wetlands can release extra CO₂ and methane, which raises the warming that a given amount of emissions produces. A feedback strong enough to keep a change going on its own is the mechanism behind a climate tipping point.