Climate sensitivity
A measure of the temperature response to a change in radiative forcing.
Example
Equilibrium climate sensitivity estimates the eventual surface warming after atmospheric CO₂ doubles, once the system approaches balance.
The catch
It differs from the warming reached during a gradual increase in concentration.
Related terms
Radiative forcing, Albedo, Atmospheric lifetime, Carbon budget, Carbon dioxide, Climate change
In more depth
Climate sensitivity, explained.
Climate sensitivity largely determines how much warming a given rise in CO₂ will bring, so its uncertainty feeds straight into every carbon budget. The IPCC's latest assessment narrowed the likely range compared with earlier reports by combining evidence from physical understanding of feedbacks, the warming observed since industrialisation and records of past climates.
A related measure links warming directly to cumulative CO₂ emissions, and that ratio sets the size of the remaining budget. The upper end of the sensitivity range dominates the risk, since it cannot be ruled out and would bring the largest damages. Avoid quoting a single value without its range, and remember that sensitivity describes the physics, so it says nothing about how much CO₂ people will emit.