Monitoring the Extent and Intensity of Urban Areas Globally using the Fusion of MODIS 500m Resolution Satellite Imagery and Ancillary Data Sources

Although only a small percentage of global land cover, urban areas significantly alter climate, biogeochemistry, and hydrology at local, regional, and global scales. Despite the fact that three billion people live in cities, information related to global geographic patterns in urban extent and density is poor. Here we present results from efforts to map the global distribution of urban land use at 463 m spatial resolution using remotely sensed data from MODIS. Our approach uses a supervised decision tree classification algorithm that we process using region-specific parameters. The resulting map shows that urban areas occupy only 0.5-1.0 percent of the Earth's land area. Because resource and energy consumption is concentrated in urban areas, the geographic distribution and intensity of urban land use has important implications for models and related studies that require information related to role of humans in the global environment.