Population predictions for the world’s largest cities in the 21st century

Abstract

We project populations to 2100 for the world's larger cities. Three socioeconomic scenarios with various levels of sustainability and global cooperation are evaluated, and individual "best fit" projections made for each city using global urbanization forecasts. In 2010, 757 million people resided in the 101 largest cities-11 per cent of the world's population. By the end of the century, world population is projected to range from 6.9 billion to 13.1 billion, with 15 per cent to 23 per cent of people residing in the 101 largest cities (1.6 billion to 2.3 billion). The disparate effects of socioeconomic pathways on regional distribution of the world's 101 largest cities in the 21st century are examined by changes in population rank for 2010, 2025, 2050, 2075 and 2100. Socioeconomic pathways are assessed based on their influence on the world's largest cities. Two aspects of the projections raise concerns about reliability: the unlikely degree of growth of cities suggested for Africa and the growth of cities in coastal settings (and likely global immigration). Trends and the effect of sustainable development on regional distribution of large cities throughout the 21st century are discussed. Keywords 21st century / cities / population projection / urban areas daniel Hoornweg is Associate Professor and richard Marceau chair in the Faculty of energy systems and nuclear science. Address: university of ontario Institute of technology (uoIt),

Communicating the deadly consequences of global warming for human heat stress

“…To assess the combined effects of population growth and global warming on city-level heat stress throughout the 21st century, we used projections from ref. 31 We also obtained the 1995 population for each city from ref. 43 to compute the reference HSB over the period 1979-2005.…”

“…These locations were identified according to the 21st century population projections from ref. 31, focusing on cities within the top 101 by population size for all three shared socioeconomic pathways (SSPs) (32) and all time slices considered by the authors (2010-2100) (Materials and Methods). Our subset of 44 cities accounted for 0.4 billion people in 2010 and is projected to reach between 0.94 and 1.1 billion by 2100 depending on the SSP.…”

Projections of Human Exposure to Dangerous Heat in African Cities Under Multiple Socioeconomic and Climate Scenarios

“…Starting with the NS approach, we retrieved country‐level population projections (KC & Lutz, , ) and urbanization projections (Jiang & O'Neill, ), from which we derived the total urban population of each African country under each of the SSPs, from 2010 to 2100, in 5‐year time steps. Employing the compound growth approach described by Hoornweg and Pope (), we then computed country‐, SSP‐, and time‐specific urban growth rates (UGRs). Assuming that cities follow their respective country's UGRs, we applied the UGRs to the current cities' population figures (United Nations, ) and projected their future population size under the five SSPs, for each 5‐year time steps (equation ).…”

“…Earth's Future compound growth approach described by Hoornweg and Pope (2016), we then computed country-, SSP-, and time-specific urban growth rates (UGRs). Assuming that cities follow their respective country's UGRs, we applied the UGRs to the current cities' population figures (United Nations, 2018) and projected their future population size under the five SSPs, for each 5-year time steps (equation (1)).…”

New Czech & Certified Methodology „Tools of Resilience“

“…Cities are perceived by people (Gerland et al, 2014) as centres of social life with greatest economic development and good opportunities and innovations. Regarding the ever-increasing costs of living in family houses, it is not possible to exclude the view (Hoornweg and Pope, 2014) that rather wealthy people will be able to live in small villages, communities or solitudes in the future.…”