Clouds are critical for understanding the historical and future evolution of climate. Clouds are the largest uncertainty in historical climate radiative forcing, due to uncertainties in how anthropogenic aerosols impact cloud processes and ultimately cloud radiative effects. How clouds respond to climate change is the largest uncertainty in climate feedbacks, which determine the future response of the climate system. Cloud forcing and feedback will be explored in the context of the community earth system model (version 2) recently released as part of the CIMP6 process. Forcing and feedback are also key for understanding how CESM2 evaluates very well against current climate and also why CESM2 has a high climate sensitivity, outside of the 'likely' IPCC range. The applicability of these results to other models and generality for the climate system will be explored.