The Gridded Population of the World (GPW) collection, now in its fourth version (GPWv4), models the distribution of human population (counts and densities) on a continuous global raster surface. Since the release of the first version of this global population surface in 1995, the essential inputs to GPW have been population census tables and corresponding geographic boundaries. The purpose of GPW is to provide a spatially disaggregated population layer that is compatible with data sets from social, economic, and Earth science disciplines, and remote sensing. It provides globally consistent and spatially explicit data for use in research, policy-making, and communications.
For GPWv4, population input data are collected at the most detailed spatial resolution available from the results of the 2010 round of Population and Housing Censuses, which occurred between 2005 and 2014. The input data are extrapolated to produce population estimates for the years 2000, 2005, 2010, 2015, and 2020. A set of estimates adjusted to national level, historic and future, population predictions from the United Nation's World Population Prospects report are also produced for the same set of years. The raster data sets are constructed from national or subnational input administrative units to which the estimates have been matched. GPWv4 is gridded with an output resolution of 30 arc-seconds (approximately 1 km at the equator).
For this latest release, eight data sets originally released in July 2016 with version 4 have been updated, and a ninth data set, on basic demographic characteristics (age and sex), has been added. The nine data sets, collectively referred to as the Revision 10 (or v4.10) data sets, incorporate boundary or population updates for 65 countries, additional attributes in the centroids and national identifier data sets, an updated water mask which includes more recent glacier data and local water data sources for high latitude countries, and additional format and resolution options.
Separate rasters are available for population counts and population density consistent with national censuses and population registers, or alternative sources in rare cases where no census or register was available. All estimates of population counts and population density have also been nationally adjusted to population totals from the United Nation’s World Population Prospects: The 2015 Revision. In addition, rasters are available for basic demographic characteristics (age and sex), data quality indicators, and land and water areas. A vector data set of the center point locations (centroids) for each of the input administrative units and a raster of national level numeric identifiers are included in the collection to share information about the input data layers.
The raster data sets are now available in ASCII (text) format as well as in GeoTiff format. Five of the eight raster data sets are also available in netCDF format. In addition, the native 30 arc-second resolution data were aggregated to four lower resolutions (2.5 arc-minute, 15 arc-minute, 30 arc-minute, and 1 degree) to enable faster global processing and support of research communities that conduct analyses at these resolutions (Table 1). All of these resolutions are available in ASCII and GeoTiff format. NetCDF files are available at all resolutions except 30 arc-second. All spatial data sets in the GPWv4 collection are stored in geographic coordinate system (latitude/longitude). Additional details on the improvements made for Revision 10 can be found on the web page “What’s New in Revision 10?”.
The GPW data collection is licensed under the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0), thus providing openly-available, gridded population data that maintains fidelity to the input census data. This is an advantage of GPW because minimally modeled census information may be analyzed in conjunction with other data sets, such as land cover and elevation, without concern for endogeneity, or double counting. See the FAQ page for more details.
In order to broaden the applicability of GPWv4, the data collection will be expanded in future releases to include global population rasters by urban/rural designations as defined by national statistics offices.
To see the previous version of GPW, visit the GPWv3 data collection.