Leaving no one off the map: A guide for gridded population data for sustainable development

Each year, nearly 160 million people are impacted by natural disasters. During a natural disaster, every second counts to save lives and to ensure that critical supplies reach those in need. To respond quickly and confidently to identify impacted communities in the wake of natural disaster, emergency organizations, like the United Nations World Food Program (WFP), are using gridded population data to estimate near real-time impacts of earthquakes and tropical storms on people and infrastructure. Gridded population data have proven essential for informing emergency response efforts and minimizing suffering. Having reliable and timely population data can make a life or death difference for individuals facing crises or living in conflict-ridden regions. These data are essential for addressing the above challenges and for critical decision-making and planning. Gridded (or raster) population maps represent the distribution of population in rows and columns of grid cells, typically defined by their latitude-longitude coordinates. An increasing number of data providers are combining information from censuses with satellite-derived geospatial features to redistribute populations and produce gridded population datasets. Despite this progress, there remains confusion or simply lack of awareness about gridded population data. The large number of different datasets now available can be overwhelming to users, particularly to those who lack the time and technical expertise to understand differences among the products and assess their strengths and weaknesses for potential applications.