The history: From WIC2013 to WIC2023

The first set of population projections following the Shared Socioeconomic Pathways (SSPs) was developed in 2013, and was documented in the Oxford University Press book "World Population and Human Capital in the Twenty-First Century" edited by Wolfgang Lutz, William Butz and Samir KC (WIC2013). These projections have found widespread use within the environmental and climate change community, among others. In 2018, an SSPs update was generated in collaboration with the European Commission Joint Research Centre. The methodology and main findings were provided in the Demographic and Human Capital Scenarios for the 21st Century: 2018 assessment for 201 countries report (edited by Lutz, Goujon, KC, Stonawski, and, Stilianakis) but not integrated into the SSP database (WIC2018).

In 2021, the SSP community requested an update of the human core of the SSPs. This updated version (WIC2023) is based on 2020 as the reference year, with adjustments to certain short-term assumptions extending to 2030. Consequently, the assumptions' trend component is grounded in recent observed changes. Moreover, the methodology was modified for fertility, mortality, migration, and education: Education-specific fertility levels have been updated with new estimates; education differentials in mortality are now country- and region-specific rather than being normalized to a single level by gender; education-specific migration rates are implemented in the projection model for the first time.

The projection results in open-access

The updated data and graphics are available here:

Data and Graphic Explorer    

and in Zenodo:


Further details on the updates and the revisions can be found in K.C. et al. (2024) and in other satellite papers focusing on the migration component (Yildiz and Abel 2024), the mortality component (Dhakad and KC 2024 - forthcoming), and the fertility component (Adhikari et al. 2024 - forthcoming).

This new version includes population projections by six levels of educational attainment from 2020 to 2100 for 200 countries according to seven scenarios (SSP1-5, SSP2-Zero Migration, and SSP2-Double Migration). The reconstruction of the population from 1950 to 2015 by education will become available in 2024.


  • In the medium (most likely) scenario from today’s perspective (WIC2023’s SSP2)  the world would peak in 2080 at 10.13 billion and slowly decline after that to reach 9.88 billion in 2100. WIC2018 had its peak happening in 2070 at 9.7 billion, with the world population at the end of the century at 9.3 billion. WIC2013 again projected lower population growth, peaking at 9.4 billion in 2070 and declining to 8.9 billion by 2100. The main reasons for a later peak and a higher population at the end of the century lie in further reductions in mortality and slower anticipated fertility decline in high-fertility countries.
  • On average the population in the projections will be much better educated than today’s because virtually everywhere the younger cohorts are better educated than the older ones. By 2050, the majority of the population would have an upper-secondary education or more (64%) according to the SSP2scenario and 29% a post-secondary education. Africa would still be the least educated world region, with 30% of the 25+ population having not completed a primary education (13% at the world level) but diminishing from 48% in 2020 (21% at the world level.

 The SSPs scenario definition

Scenario Definition
Rapid Development (SSP1) Population Component of Rapid Development (SSP1): This scenario assumes a future that is moving toward a more sustainable path, with educational and health investments accelerating the demographic transition, leading to a relatively low world population. The emphasis is on strengthening human well-being. This is associated with high education, low mortality, and low fertility. Migration levels are assumed to be medium for all countries under this SSP.
Medium (SSP2) Population Component of Medium (SSP2): This is the middle-of-the-road scenario that can also be seen as the most likely path for each country. It combines for all countries medium fertility with medium mortality, medium migration, and the Global Education Trend (GET) education scenario.
Stalled Development (SSP3) Population Component of Stalled Development (SSP3): This scenario portrays a world separated into regions characterized by extreme poverty, pockets of moderate wealth, and many countries struggling to maintain living standards for rapidly growing populations. This is associated with low education, high mortality and high fertility. Due to the emphasis on security and barriers to international exchange, migration is assumed to be low for all countries.
Inequality (SSP4) Population Component of Inequality (SSP4): This scenario assumes increasing inequalities and stratification both across and within countries. It assumes high fertility and mortality scenarios in high-fertility countries and low fertility and medium mortality scenarios in low-fertility countries combined with medium migration scenarios. In terms of education, the SSP3 education transitions (CER) are decreased by 10% for levels up to lower secondary education, keeping the SSP2 (GET) education transitions for upper and post-secondary education.
Conventional Development (SSP5) Population Component of Conventional Development (SSP5): This scenario is similar to SSP1 for the fertility, mortality, and education assumptions except that it combines them with a high migration scenario in a context of widespread globalization.


Medium - Zero Migration (SSP2 - ZM) Population Component of Medium (SSP2): Middle of the road scenario with zero migration flows.


Medium - Double Migration (SSP2 - DM)    Population Component of Medium (SSP2): Middle of the road scenario with double migration flows.

The world population according to SSP1 to SSP5 by levels of educational attainment

SSP chart © IIASA


The suggested citation for data and plots from this website is:

K.C., S., Dhakad, M., Potancokova, M., Adhikari, S., Yildiz, D., Mamolo, M., Sobotka, T., Zeman, K., Abel, G., Lutz, W., and Goujon, A. (2024). Updating the Shared Socioeconomic Pathways (SSPs) Global Population and Human Capital Projections. IIASA Working Paper. Laxenburg, Austria: WP-24-003. https://pure.iiasa.ac.at/19487. Available at: http://www.wittgensteincentre.org/dataexplorer.

Wittgenstein Centre

POPJUS is one of the three pillars of The Wittgenstein Centre for Demography and Global Human Capital, a collaboration among the Austrian Academy of Sciences (ÖAW), the International Institute for Applied Systems Analysis (IIASA) and the University of Vienna.

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