Future of the human climate niche | PNAS

The authors show that for thousands of years, humans have concentrated in a surprisingly narrow subset of Earth’s available climates, characterized by mean annual temperatures around ∼13 °C. This distribution likely reflects a human temperature niche related to fundamental constraints. They demonstrate that depending on scenarios of population growth and warming, over the coming 50 y, 1 to 3 billion people are projected to be left outside the climate conditions that have served humanity well over the past 6,000 y. Absent climate mitigation or migration, a substantial part of humanity will be exposed to mean annual temperatures warmer than nearly anywhere today.


The realized human climate niche relative to available combinations of MAT and precipitation. Human populations have historically remained concentrated in a narrow subset (A–C) of the available climatic range (G), which is not explained by soil fertility (H) or potential primary productivity (I). Current production of crops (D) and livestock (E) are largely congruent with the human distribution, whereas gross domestic product peaks at somewhat lower temperatures. Reconstructions of human populations 500 BP are based on the HYDE database, whereas those for 6 Ky BP are based on ArchaeoGlobe (https://doi.org/10.7910/DVN/CQWUBI, Harvard Dataverse, V4). NPP, net primary productivity. See SI Appendix, Methods.

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