All species have an environmental niche, and despite technological advances, humans are unlikely to be an exception. Here, we demonstrate that for millennia, human populations have resided in the same narrow part of the climatic envelope available on the globe, characterized by a major mode around 11°C–15°C mean annual temperature (MAT).

… in the absence of migration, [by 2070] one third of the global population is projected to experience a MAT >29°C currently found in only 0.8% of the Earth’s land surface, mostly concentrated in the Sahara.