FuturePop - Global Gridded Population Projections at 90m resolution

Population projections for alternative socio-economic scenarios are crucial to understand climate change impacts. Current global gridded population projections are only available at coarse resolutions (~1km) that are inconsistent with the latest hazard models. Thus, climate change impact studies often utilise sub-optimum datasets by using coarse resolution gridded population predictions or present day population, and therefore may not adequately represent future population. To fill this gap, we use the latest datasets that align with the policy relevant Shared Socioeconomic Pathway (SSP) Scenarios and CMIP6 projections to create the first gridded population at ~90m resolution globally. We call this new dataset FuturePop. Projections are made at decadal intervals and extend to 2100 for each of the 5 SSP scenarios. Our method uses country level population and % urban projections from the SSP Database, redistributing population based on delineation of rural and urban areas. We add sophistication to our method by considering associated information such as travel time, and also include predictions of urban expansion. Comparison to existing global and regional datasets show FuturePop has considerable skill in predicting plausible population changes and redistribution. Lastly, we demonstrate the importance of using FuturePop for future flood risk compared to existing gridded population projections. Hazard footprints typically have horizontal length scales of tens to thousands of meters, thus it is crucial to depict populations at these scales to accurately estimate future flood exposure.