How Long Does it Take for the Earth's Climate System to Reach Equilibrium?
Little Big Econ State Forest (just because it's pretty) Any given climate forcing affects the Earth's Energy Imbalance (EEI) - that is, it affects the amount of energy entering the climate system vs energy escaping into space. When a forcing occurs, such as from an increase in CO2, the imbalance is created and surface temperature increases until EEI returns to equilibrium (that is, EEI = 0). But how long does this take? That is, what is the lag between a climate forcing and the new equilibrium temperature? It turns out, this depends on sensitivity and the rate of temperature increase, but it is possible estimate the time to achieve this equilibrium with a forcing. But this is going to be rather math-intensive. Apologies in advance! We can begin with a simple energy balance equation: (1) ΔF = ΔT/ λ + EEI, where λ is sensitivity (ECS/F2x) ECS is Equilibrium Climate Sensitivity F2x is the forcing for doubling CO2 EEI is the Earth's Energy Imbalance ΔF is the change in radiati...