Input data set: National, gridded historical population

Direct human forcing: national and gridded historical population data for ISIMIP3a in the period 1850 to 2014. Estimates are available for total as well as urban and rural population counts.

Annual national population counts are derived from the 2019 UN World Population Prospects (WPP) database for the period from 1950–2021 (United Nations, 2019). The 2019 revision of the WPP provides census-based population numbers from 1950 through 2020. For the year 2021, we use the “medium variant” of the probabilistic forecast also provided by the WPP. For countries not covered in the database, estimates are taken from the MissingIslands dataset (Arujo et al., 2021) to finally provide population data for 249 countries.

The population data are adopted from HYDE v3.3 (private communication with K. Klein Goldewijk). Just like the original dataset we provide total, rural and urban population per grid cell. The original data was on a 1/12°×1/12° grid and has been interpolated to ISIMIP's 1/2°×1/2° grid via cdo remapcon. Furthermore, the map was modified to comply with the ISIMIP fractional land-sea-mask (Perrette 2022).

Before the year 2000 HYDE provides data every ten years, the intermediate years have been filled by linear interpolation. Also, the original HYDE data ends in 2020, so to cover the whole ISIMIP3a time frame the final year 2020 has been duplicated as 2021. This way annual coverage of 1850 to 2021 has been achieved.

All grid cells of a country, as defined by the ISIMIP fractional country map (Perrette 2022), have been rescaled such that the country's total population matches the numbers provided in the national population data (United Nations 2009). Since the national data only starts in 1950, all years prior to 1950 have been rescaled by the scaling factors of 1950.

- Arujo, E., Bodirsky, B. L., Crawford, M. S., Leip, D., and Dietrich, J.: MissingIslands dataset for filling in data gaps from the WDI datasets, Zenodo [data set], https://doi.org/10.5281/zenodo.4421504, 2021.
- Klein Goldewijk, K., Beusen, A., Doelman, J. and Stehfest, E.: Anthropogenic land use estimates for the Holocene – HYDE 3.2, Earth System Science Data, 9(2), 927–953, 2017. https://doi.org/10.5194/essd-9-927-2017
- Mahé Perrette (2022): ISIpedia country masks (v1.1). ISIMIP Repository. https://doi.org/10.48364/ISIMIP.635131.1
- United Nations, Department of Economic and Social Affairs: Population Division (2019), World Population Prospects 2019, archive [data set], https://population.un.org/wpp/Download/Archive/Standard/ (last access: 22 December 2023), 2019.

With version 1.1, we provide gridded population data, that is based on HYDE v3.3 (private communication with K. Klein Goldewijk, to be published). Just like the original dataset we provide total, rural and urban population per grid cell.

Version 1.2 corrects a mistake in the coastal regions that led to a too high population in those grid cells.

For ISIMIP participants, these files are available for download on the DKRZ cluster server using the path /work/bb0820/ISIMIP/ISIMIP3a/InputData/socioeconomic/pop/

For external users, these data can be downloaded from the ISIMIP Repository using the link below.