A global Cloud Resolving Model (CRM) is used in a climate sensitivity test for an aqua planet in this first attempt to evaluate climate sensitivity without cumulus parameterizations. Results from a control experiment and an experiment with global sea surface temperature (SST) warmer by 2 K are examined. Notable features in the simulation with warmer SST include a wider region of active convection, a weaker Hadley circulation, mid-tropospheric moistening in the subtropics, and more clouds in the extratropics. Negative feedback from short-wave radiation reduces the climate sensitivity parameter compared to a result in a more conventional model with a cumulus parameterization.