We thank three anonymous reviewers for their thoughtful criticisms of this paper. We acknowledge the World Climate Research Programme's Working Group on Coupled Modelling, which is responsible for CMIP, and we thank the climate modeling groups (listed in Table 2) for producing and making available their model output. For CMIP, the U.S. Department of Energy's (DOE) Program for Climate Model Diagnosis and Intercomparison provides coordinating support and led development of software infrastructure in partnership with the Global Organization for Earth System Science Portals. The work of MDZ, SAK, and KET was supported by the Regional and Global Climate Modeling Program of the Office of Science at the DOE and was performed under the auspices of the DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. TA, MJW, and JMG were supported by the Joint DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). MJW is also supported by funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 244067 via the EU Cloud Intercomparison and Process Study Evaluation project (EUCLIPSE).
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For further discussion of the deviations from linearity in the early stages of the abrupt4xCO2 simulation, please refer to section 4 of Andrews et al. (2012b).
Ensemble mean uncertainties represent the standard deviation across models.
One must bear in mind that such a decomposition can sometimes be misleading (e.g., large reductions solely in low clouds can cause a large positive LW cloud altitude feedback when such low cloud anomalies would have little actual effect on LW fluxes at the TOA).