An Assessment of Radiative Forcing, Feedbacks, and Rapid Adjustments in Coupled Ocean Atmosphere Models

Radiative kernels are used in conjunction with linear forcing-feedback framework to analyze the direct radiative forcing from quadrupling CO₂, the rapid adjustments to this forcing, and the radiative feedbacks that develop in response to the resulting surface warming in an ensemble of coupled ocean-atmosphere models. It is found that the total forcing, the sum of the direct radiative forcing and rapid radiative adjustments, is consistent in strength and intermodel range with that determined using Gregory et al. (2004) method. Among feedback variables, clouds are identified as the primary cause for intermodel discrepancy in the rapid radiative adjustments as well as for intermodel discrepancy in the radiative feedbacks. However, relatively small estimates of cloud adjustment are obtained compared to previous studies. This discrepancy is at least partially attributable to a small, but non-negligible global-mean warming in fixed sea surface temperature experiments which aliases a surface-driven feedback response into estimates of the adjustments.