{"id":10550,"date":"2026-05-18T00:00:00","date_gmt":"2026-05-18T00:00:00","guid":{"rendered":"https:\/\/veilles-affaires-sociales.fr\/?p=10550"},"modified":"2026-05-18T00:00:00","modified_gmt":"2026-05-18T00:00:00","slug":"population-tool-how-will-populations-across-the-world-change-in-the-21st-century","status":"publish","type":"post","link":"https:\/\/veilles-affaires-sociales.fr\/?p=10550","title":{"rendered":"Population tool: How will populations across the world change in the 21st century?"},"content":{"rendered":"<div class=\"centered-article-header__breadcrumbs-container col-start-4 span-cols-8 col-md-start-2 span-md-cols-12\">\n<p><a href=\"https:\/\/ourworldindata.org\/\">Home<\/a><a href=\"https:\/\/ourworldindata.org\/population-growth\" data-track-note=\"breadcrumb\">Population Growth<\/a><\/p>\n<\/div>\n<header class=\"centered-article-header align-center grid grid-cols-8 span-cols-8 col-start-4 grid-md-cols-6 span-md-cols-12 col-md-start-2\">\n<h2 class=\"centered-article-header__subtitle col-start-2 span-cols-6 span-md-cols-6 col-md-start-1\">We created an interactive tool that lets you test how changes in fertility rates, life expectancy, and migration rates will change future populations.<\/h2>\n<div class=\"centered-article-header__meta-container col-start-2 span-cols-6 span-md-cols-6 col-md-start-1 grid grid-cols-2\">\n<div class=\"centered-article-header__meta-container-left span-cols-1 span-sm-cols-2\">\n<p>By <a href=\"https:\/\/ourworldindata.org\/team#sophia-mersmann\">Sophia Mersmann<\/a> (data visualization), <a href=\"https:\/\/ourworldindata.org\/team#daniel-bachler\">Daniel Bachler<\/a> (concept &amp; modeling),  and <a href=\"https:\/\/ourworldindata.org\/team\/hannah-ritchie\">Hannah Ritchie<\/a> (writing)<\/p>\n<p>May 18, 2026<\/p>\n<\/div>\n<p><a href=\"https:\/\/ourworldindata.org\/population-simulation-tool#article-citation\" class=\"display-block\">Cite this article<\/a><a href=\"https:\/\/ourworldindata.org\/population-simulation-tool#article-licence\" class=\"display-block\">Reuse our work freely<\/a><\/p>\n<\/div>\n<\/header>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">How will populations change in the future?<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">Demographers model their scenarios using assumptions about key demographic changes, most notably fertility rates, life expectancy, and migration rates.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">In our work, we <a href=\"https:\/\/ourworldindata.org\/explorers\/population-and-demography?indicator=Population&amp;Sex=Both+sexes&amp;Age=Total&amp;Projection+scenario=Medium&amp;country=CHN~IND~USA~IDN~PAK~NGA~BRA~JPN\" class=\"span-link span-linked-chart\">often present<\/a> the projections published by the United Nations.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">No one knows with certainty what the migration rate will be in decades from now, or how many children people will have. So it\u2019s worth asking what the population will look like if things turn out differently from what the UN or other demographers assume.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">We have built a population simulation tool that helps answer this question.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">This tool is deliberately simple: small enough to run in a browser and nevertheless capable of modeling whole populations based on the key demographic inputs. It is less detailed than the models expert demographers use, and our aim is not to replace them. We hope you find this tool useful for developing an understanding of the difference that changes in demographic variables can make to the size and structure of future populations.<\/p>\n<hr class=\"article-block__horizontal-rule col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\" \/>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">Here\u2019s how to use the tool below.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\"><strong>First<\/strong>, select your country from the dropdown in the title.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\"><strong>Second<\/strong>, in the first panel, change any of the three inputs: fertility rates, life expectancy, and net migration rates. You can do this at three points in time: 2030, 2050, and 2100.<\/p>\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\"><strong>Finally<\/strong>, in the second and third panels, you\u2019ll see what the output of your assumptions would mean for population numbers and age structure in the country.<\/p>\n<div class=\"article-block__callout col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">\n<p class=\"article-block__text col-start-5 span-cols-6 col-md-start-3 span-md-cols-10 span-sm-cols-12 col-sm-start-2\">Many thanks to Mallika Snyder for her valuable feedback and suggestions on this tool. We\u2019d also like to thank Max Roser and Edouard Mathieu for comments and editorial feedback, and Marwa Boukarim for input on design and visualization.<\/p>\n<\/div>\n<section class=\"grid grid-cols-12-full-width col-start-1 col-end-limit no-dividers\">\n<div class=\"col-start-4 span-cols-8 col-md-start-3 span-md-cols-10 col-sm-start-2 span-sm-cols-12\">\n<h3 class=\"align-center\">Cite this work<\/h3>\n<p>Our articles and data visualizations rely on work from many different people and organizations. When citing this article, please also cite the underlying data sources. This article can be cited as:<\/p>\n<div>\n<div class=\"wp-code-snippet wp-code-snippet--dark\">\n<pre class=\"wp-code-snippet__code\">Sophia Mersmann, Daniel Bachler, and Hannah Ritchie (2026) - \u201cPopulation tool: How will populations across the world change in the 21st century?\u201d Published online at OurWorldinData.org. Retrieved from: 'https:\/\/archive.ourworldindata.org\/20260528-080101\/population-simulation-tool.html' [Online Resource] (archived on May 28, 2026).<\/pre>\n<\/div>\n<\/div>\n<p>BibTeX citation<\/p>\n<div>\n<div class=\"wp-code-snippet wp-code-snippet--dark\">\n<pre class=\"wp-code-snippet__code\">@articleowid-population-simulation-tool,\n    author = Sophia Mersmann and Daniel Bachler and Hannah Ritchie,\n    title = Population tool: How will populations across the world change in the 21st century?,\n    journal = Our World in Data,\n    year = 2026,\n    note = https:\/\/archive.ourworldindata.org\/20260528-080101\/population-simulation-tool.html\n<\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n<section class=\"grid grid-cols-12-full-width col-start-1 col-end-limit\">\n<div class=\"col-start-4 span-cols-8 col-md-start-3 span-md-cols-10 col-sm-start-2 span-sm-cols-12\"><img decoding=\"async\" src=\"https:\/\/ourworldindata.org\/owid-logo.svg\" alt=\"Our World in Data logo\" width=\"104\" height=\"57\" \/>\n<h3>Reuse this work freely<\/h3>\n<p>All visualizations, data, and articles produced by Our World in Data are completely open access under the <a href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">Creative Commons BY license<\/a>. You have the permission to use, distribute, and reproduce these in any medium, provided the source and authors are credited.<\/p>\n<p>The data produced by third parties and made available by Our World in Data is subject to the license terms from the original third-party authors. We will always indicate the original source of the data in our documentation, so you should always check the license of any such third-party data before use and redistribution.<\/p>\n<p>All of <a href=\"https:\/\/ourworldindata.org\/faqs#how-can-i-embed-one-of-your-interactive-charts-in-my-website\">our charts can be embedded<\/a> in any site.<\/p>\n<\/div>\n<\/section>\n<p>\u00a0<a href=\"https:\/\/ourworldindata.org\/population-simulation-tool\" target=\"_blank\" class=\"feedzy-rss-link-icon\">Lire la Suite<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>HomePopulation Growth We created an interactive tool that lets you test how changes in fertility rates, life expectancy, and migration rates will change future populations. By Sophia Mersmann (data visualization), [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":10543,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[26],"tags":[233,226],"class_list":["post-10550","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-donnees-etudes-evaluation-et-prospective","tag-ourworldindata","tag-sources-etrangeres"],"_links":{"self":[{"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=\/wp\/v2\/posts\/10550","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10550"}],"version-history":[{"count":0,"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=\/wp\/v2\/posts\/10550\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=\/wp\/v2\/media\/10543"}],"wp:attachment":[{"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10550"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10550"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/veilles-affaires-sociales.fr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10550"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}