Abstract We document the wide range of global cloud feedbacks that can be obtained from a global model's single perturbation experiment. The wide range results from combinations of different options of producing cloud subgrid variability, interpreting the resulting cloud fields in terms of joint histograms that can relate or not to observations, and calculating the feedback from perturbed cloud fields with the cloud radiative kernel approach. The global cloud feedback in terms of net (=shortwave + longwave) radiation changes corresponding to a +4K perturbed SST experiment conducted with NASA's GEOS model ranged between 0.4 and 1.1 Wm −2 K −1 across our 15 combinations. Our findings underscore that implementation details matter greatly and need to be documented when presenting estimates of climate model cloud feedback.
Lee et al. (Thu,) studied this question.