Shared Socioeconomic Pathways (SSP1–3 and SSP5) Population Projections to 2300 (zen2300V15)

THIS IS VERSION SSP2300_V02 (supersedes SSP2300_V01 of 10 February 2026). Read README.md first. This dataset provides population and human-capital projections for four Shared Socioeconomic Pathways (SSP1, SSP2, SSP3 and SSP5) from 2020 to 2300 in five-year steps, by country or territory (200), sex, five-year age group and six levels of educational attainment, together with the 28 UN regional and world aggregates. Two SSP2 variants with long-run fertility converging to 1.50 and 2.00 children per woman are included as sensitivity runs. There is no SSP4 extension. Each scenario is one CSV file; a recode dictionary, a file overview, a validation summary and a checksum manifest are included. The years 2020–2100 are the Wittgenstein Centre WIC2023 projections, version V15 (https://doi.org/10.5281/zenodo.20447835), copied unchanged. V15 has 2020 as base year and is the vintage served by the Wittgenstein Centre Human Capital Data Explorer. Each extension starts from the 2100 state of its pathway and does not alter it; validation_summary.tsv records this seam check. Long-run assumptions after 2100, in brief. Fertility: the education-specific age schedule of 2095–2100 converges linearly to a common ultimate schedule reached in 2200 and is then held; the ultimate total fertility rate is 1.75 in SSP2, 1.53 in SSP1 and SSP5, and 1.97 in SSP3. These levels are imposed. Mortality: each country's 2015–2095 gain in life expectancy at birth is continued until 105 years and then held; education differentials in survival converge by 2150 (2200 in SSP3). Migration: net international migration is held at zero after 2100. Education: attainment progression ratios are extrapolated on the logit scale. Changes from version 1. (1) Each file is one continuous series from 2020 to 2300; version 1 covered 2100–2300 only. (2) Columns region_level and region_label separate the 200 countries from the aggregates; filter region_level == "country" before summing. The aggregates are sums of the 200 countries and use the same codes as WIC2023 V15. (3) The newborn rows (agest = -5) are kept and documented: they hold the births of each period and the deaths among those newborns, are not a stock, and must be excluded when summing population. (4) Flows are recorded as missing rather than zero in 2300, because no period starts there; in version 1 the zeros produced an apparent drop in the last period. (5) The two SSP2 fertility-sensitivity files are added. (6) The runs are the April 2026 reruns behind the companion article. Note on the SSP Scenario Explorer. The IIASA SSP Scenario Explorer (Basic Elements 2025, model IIASA-WiC POP 2025) holds a 2025-rebased update, in which every pathway starts from the SSP2 population of 2025. SSP2 is the same as here; SSP1, SSP3 and SSP5 differ. The rebased data are published at https://doi.org/10.5281/zenodo.21738148 (2025–2100) and https://doi.org/10.5281/zenodo.21738636 (2100–2300). Note on Mayotte and other small territories. Mayotte grows from 0.3 million in 2020 to 2.5 million in 2100 in WIC2023 and to about 8.6 million by 2200 under SSP2, which is implausible for an island of its size. Version 1 announced a correction; none is made in this version. The 2020–2100 path is the published WIC2023 projection, already widely used, and the extension does not alter it. After 2100 net international migration is held at zero in every country, so the model cannot respond to the lack of living space through emigration. This will be addressed in a future revision: a separate exercise that takes available living space into account could adjust Mayotte and other territories with similar trajectories. Until then, results for these territories should be used with caution. Companion article: KC, S., Humanity after the peak: extending Shared Socioeconomic Pathway population and human-capital projections to 2300 (in revision). Preprint: https://doi.org/10.31235/osf.io/sm4n8_v1. The data are scenario outputs, not probabilistic forecasts.