Identifying discrepant regions in urban mapping from historical and projected global urban extents

Abstract

Although several products of the global urban extent with fine resolutions (e.g. 30 m-38 m) have been developed, quantitative evaluations of these products across spaces and times are still missing, which is crucial to future urban growth modeling. Here, we analysed the discrepancy of six global fine resolution urban extent products across spaces and times. First, we measured the area variations of urban extent among these urban products in each 0.25° grid used in the Land-Use Harmonisation (LUH2), a commonly used product with future projections in Earth system modelling. Then, we analysed the potential urban growth within each 0.25° grid using the LUH2 data under eight scenarios shaped by shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs). Finally, we identified those regions with a large discrepancy and noticeable growth of urban extent under historic and SSP-RCPs scenarios. We found the discrepancy among six products occurs in either highly developed (e.g. the United States-US and Europe) or rapidly developing (e.g. China) regions. Moreover, Eastern US, Europe, and West Africa deserve more attention in the future due to their distinct urban growth and relatively large discrepancy of urban areas. The derived results are crucial to future global urban sprawl modeling.