For constant
forcing, final
equilibrium has
Ts=Td=F/λ. During transient warming
Td<Ts, so the radiative response inferred from
a recent global
energy budget is
λeff=λ+λ′(1−Td/Ts)>λ. If that response were mistaken for the final
feedback, the inferred
equilibrium climate sensitivity would be too small. Summing the two
equations makes the distinction explicit:
d(CsTs+CdTd)/dt=F−λTs−λ′(Ts−Td).