A recent paper suggested that 'climate sensitivity' derived from a new paleo-CO2 record is around 7.2ºC (for equilibrium climate sensitivity ECS) and ~13.9ºC (Earth System Sensitivity - ESS) for a doubling of CO2. Some press has suggested that this means that Earth’s Temperature Could Increase by 25 Degrees (F). Huge if true! Fortunately these numbers should not be taken at face value, but we need to dig into the subtleties to see why. ...
Some good digging - indeed it is hard to understand all the different ways to define and interpret climate sensitivity.