 Among the simplest climate models are energy balance models (EBMs), designed to represent earth’s surface energy budget in a highly aggregate way (McGuffie &amp; Henderson-Sellars 2014: Ch.3). These models, which often have surface temperature as their sole dependent variable, are constructed using both physical theory (e.g., the Stefan-Boltzmann equation) and empirical parameters (e.g., representing the albedo of the earth and the emissivity of the atmosphere). Zero-dimensional EBMs represent the entire climate system as a single point. They can be used to calculate by hand an estimate of the globally-averaged surface temperature when the system is in radiative equilibrium. One-dimensional (1-D) and two-dimensional (2-D) EBMs take a similar energy-budget approach but represent average temperature at different latitudes and/or longitudes and account in a rough way for the transport of heat between them (see Sellers 1969 for an early example). The equations of 1-D and 2-D EBMs are usually solved with the help of digital  computers.[1]