claim: In fact, the authors go on to estimate climate sensitivity from their findings, calculate a value between 2.3 to 4.1°C.
evidence: IPCC AR4 WG1 Ch9 2007, p. 690: "Recent estimates indicate a relatively small combined effect of natural forcings on the global mean temperature evolution of the second half of the 20th century, with a small net cooling from the combined effects of solar and volcanic forcings."