The C-ROADS (Climate Rapid Overview and Decision Support) simulator is based on the biogeophysical and integrated assessment literature and includes representations of the carbon cycle, other greenhouse gases, radiative forcing, global mean surface temperature, and sea level change. The simulation is grounded in the established literature yet remains simple enough to run quickly on a personal computer.

Model users determine the path of net GHG emissions (e.g., CO₂ from fossil fuels and land use, non-CO₂ GHGs including CH₄, N₂O, F-Gases, Montreal Protocol Gases and CO₂ sequestration from afforestation), at the country or regional level, through 2100. The model calculates the path of atmospheric CO₂ and other GHG concentrations, global mean surface temperature, and mean sea level rise resulting from these emissions. The user can choose the level of regional aggregation. Currently, users may choose to provide emissions inputs for one, three, or six different blocs of countries.