### Population density

Population density is used in IMAGE 2.4 within the land-cover model. This model uses several criteria ('land-use rules') to calculate preferences to select cells. Based on these preferences, the model will use cells with the highest preferences for specific land uses. One of the criteria used to give preferences to cells is population density in the grid cells considered. The higher the population density, the sooner a grid cell will be used. Migration within a region or across regions is not accounted for in the IMAGE 2.4 model. The population density is simply scaled to regional population densities over time, which means that regional patterns of population density remain constant over time.