Evaluating Observational Constraints on Intermodel Spread in Cloud, Temperature, and Humidity Feedbacks

Abstract Uncertainty in climate feedbacks is the primary source of spread projected surface temperature responses to anthropogenic forcing. Cloud feedback persistently appears as main disagreement future projections while combined lapse‐rate plus water vapor (LR + WV) a smaller (30%), but non‐trivial uncertainty sensitivity. Here we attempt observationally constrain an effort reduce their intermodel uncertainties. The observed interannual variation provides useful constraint on long‐term cloud feedback, evidenced by consistency global‐mean values and regional contributions both timescales. However, variability does not serve LR WV spread, which find dominated varying tropical relative humidity (RH) response interhemispheric warming differences under clear‐sky conditions RH‐fixed all‐sky conditions.