Climate forcings fundamentally result from changes in the rate of incoming solar radiation; thefraction of solar radiation that is reflected back to space (albedo); and the rate of infraredradiation emitted by the climate system to space. Dynamic climate models use mathematicalexpressions of physical processes and known initial conditions for model calculations ofresponses to such forcings.Modeling the ClimateClimate modeling is essential to modern climate science and climate change research. A modelis a representation or simulation of a real system, incorporating essential features (or variables)of a system while omitting details considered neither needed nor predictable. Figure 1 displaysthe features of climate models, systems of mathematical equations representing the basic laws ofphysics, fluid motion, and chemistry.Climate modeling is a challenging endeavor. The interacting subsystems of Earth's climatesystem each have different spatial scales, from cloud droplets to ocean currents, while feedbackswithin and between them depend on ever-changing factors. Surface and satellite observations areimproving the accuracy of the variables we put into climate models