The global human population switched from depensation to compensation in the 1950s
Prof Corey J. A. Bradshaw
Global Ecology | Partuyarta Ngadluku Wardli Kuu, Flinders University, Adelaide, Australia
February 2024
Accompanies (now outdated) preprint:
Bradshaw, CJA, MA Judge, DT Blumstein, PR Ehrlich, ANZ Dasgupta, M Wackernagel, LJZ Weeda, PN Le Souëf. 2024. Global human population ended self-facilitation in the 1950s. SSRN doi:10.2139/ssrn.4788003
and paper:
Bradshaw, CJA, MA Judge, DT Blumstein, PR Ehrlich, ANZ Dasgupta, M Wackernagel, LJZ Weeda, PN Le Souëf. Global human population has surpassed Earth’s sustainable carrying capacity. Environmental Research Letters doi:10.1088/1748-9326/ae51aa
The ecological concept of human carrying capacity is necessarily complicated because human beings are the “ultimate ecosystem engineers” who moderate the environment for their benefit. For at least the last few hundred years, human ingenuity, access to massive stocks of fossil fuels, and technological development have driven facilitation whereby increasing human abundance has promoted higher population growth rates. However, this positive relationship broke down during the 1950s, and by 1962, the global human population entered a phase where the growth rate consistently declined as population increased. The onset of this negative phase occurred 8 years before a global biocapacity deficit began in 1970. The onset of the negative phase also varies regionally, with the lowest-income and highest fertility regions entering this phase later than higher-income regions. A Ricker logistic model fitted to the negative phase predicts that the global population could reach 11.7 to 12.4 billion people between 2067 and 2076. The same model fitted to the facilitation phase predicts a maximum population of 2.5 billion people that Earth might be able to maintain. The negative phase also correlates strongly with the trend in global temperature anomaly, ecological footprint, and total emissions, with more of its variation explained by increasing population size rather than increasing per-capita consumption. The Earth cannot sustain the future human population, or even today’s, without a major overhaul of socio-cultural practices for using land, water, energy, biodiversity, and other resources.
humanpoptransitionR1.R(main code)new_lmer_AIC_tables3.R(source functions)r.squared.R(source functions)
- agestructure1950_2021.csv: United Nations Population Division age structure data from 1950-2021
- AGO.csv: United Nations Population Division data for Angola
- BDI.csv: United Nations Population Division data for Burundi
- BFA.csv: United Nations Population Division data for Burkina Faso
- china1950-2023.csv: United Nations Population Division data for China
- COD.csv: United Nations Population Division data for Republic of Congo
- consump.csv: global consumption data, global emissions data, and global ecological footprint data
- continent.country2.csv: country-region categories
- demog.csv: regional demographic time series (United Nations Population Division data)
- gdppcPPP.csv: purchasing power parity-corrected gross domestic product per country time series (World Bank data)
- GMB.csv: United Nations Population Division data for Gambia
- MLI.csv: United Nations Population Division data for Mali
- Nchild-01.csv: number of children aged 0-1 years from 1950-2021 (United Nations Population Division)
- NER.csv: United Nations Population Division data for Niger
- NGA.csv: United Nations Population Division data for Nigeria
- Npre1950.csv: historical estimates of global population size
- popregions.csv: population data by major global region (United Nations Population Division)
- popXtempanom.csv: world population size relative to global temperature anomaly (HadCRUT.05.0.3.0)
- TCD.csv: United Nations Population Division data for Chad
- UGA.csv: United Nations Population Division data for Uganda
- UNpop.csv: United Nations Population Division data
- worldpophist.csv: historical United Nations Population Division data
- <wid_all_data>: download full World Inequality Database dataset to a 'wid_all_data' directory
The main script includes global and selected regional World Inequality Database Gini coefficient analyses against global temperature anomaly, ecological footprint, and CO2-e emissions. It also fits resampled boosted regression trees for each global change variable using population size, per-capita consumption, and each global Gini definition as predictors. For Sub-Saharan Africa, Latin America, and Middle East/North Africa, it sources annual country primary-energy consumption from Our World in Data and ecological footprint and population from the Global Footprint Network, then writes population-weighted regional energy use and total/per-capita footprint to data/WID_regional_energy_footprint.csv. It also sums Climate Watch territorial greenhouse-gas sectors, supplied through Our World in Data, to create regional CO2-e totals and per-capita values in data/WID_regional_emissions.csv; these data cover 1990-2023. The pipeline fits regional total-footprint and CO2-e boosted regression trees with regional population, energy use, and each regional Gini definition as predictors. Download the World Inequality Database bulk files separately and set WID_DATA_DIR to the directory containing WID_data_XX.csv before running the script. The pipeline uses published World Inequality Database series for the world, Sub-Saharan Africa, Latin America, and Middle East/North Africa; it does not average national Gini coefficients to construct regions that lack an aligned World Inequality Database aggregate.
boot, dismo, gbm, ggplot2, gridExtra, lmtest,performance, plotrix, sjPlot, tmvnsim,truncnorm, wCorr
