We can obtain this «long - term» climate sensitivity from paleoclimate data by finding the scale factor that causes the GHG forcing to match the paleoclimate temperature change as accurately as possible. (theoildrum.com)
For all the talk about CO2, there is a surprising lack of paleoclimate data on that peskly gas, but what I have been able to find is interesting. (theinconvenientskeptic.com)
Paleoclimate data for sea level change indicate that sea level changed at rates of the order of a meter per century [81]--[83], even at times when the forcings driving climate change were far weaker than the human - made forcing. (journals.plos.org)