Long-term population projections: Scenarios of low or rebounding fertility.

Autor: Spears D; Economics Department, University of Texas at Austin, Austin, TX, United States of America.; Population Wellbeing Initiative, University of Texas at Austin, Austin, TX, United States of America., Vyas S; Population Wellbeing Initiative, University of Texas at Austin, Austin, TX, United States of America.; Hunter College and CUNY Institute for Demographic Research, both at City University of New York, New York, NY, United States of America., Weston G; Population Wellbeing Initiative, University of Texas at Austin, Austin, TX, United States of America., Geruso M; Economics Department, University of Texas at Austin, Austin, TX, United States of America.; Population Wellbeing Initiative, University of Texas at Austin, Austin, TX, United States of America.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2024 Apr 04; Vol. 19 (4), pp. e0298190. Date of Electronic Publication: 2024 Apr 04 (Print Publication: 2024).
DOI: 10.1371/journal.pone.0298190
Abstrakt: The size of the human population is projected to peak in the 21st century. But quantitative projections past 2100 are rare, and none quantify the possibility of a rebound from low fertility to replacement-level fertility. Moreover, the most recent long-term deterministic projections were published a decade ago; since then there has been further global fertility decline. Here we provide updated long-term cohort-component population projections and extend the set of scenarios in the literature to include scenarios in which future fertility (a) stays below replacement or (b) recovers and increases. We also characterize old-age dependency ratios. We show that any stable, long-run size of the world population would persistently depend on when an increase towards replacement fertility begins. Without such an increase, the 400-year span when more than 2 billion people were alive would be a brief spike in history. Indeed, four-fifths of all births-past, present, and future-would have already happened.
Competing Interests: The authors have declared that no competing interests exist.
(Copyright: © 2024 Spears et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
Databáze: MEDLINE
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