paleo-CO2

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.