Climate Sensitivity—Evidence from Models and Observations

Climate sensitivity to natural and anthropogenic climate forcings is a function of the climate state and time scale. Our understanding of climate sensitivity is improved by combining climate model studies with a broad range of observational data. I will discuss and compare results from a range of climate model types and empirical information from time scales from a few years to the age of Earth. Perturbing climate forcings, such as volcanic eruptions and large scale carbon injections to the atmosphere, provide useful constraints, as does comparative planetology.