Simply put: Xu et al. (2020)
This post is based on the paper " Future of the human climate niche " by Xu et al., published in PNAS. Source The authors begin by establishing that humans have lived in a preferred temperature band for at least the last 6000 years . This preferred range of temperature has remained constant, irrespective of the fact that much has changed for human societies from the early days of farming, hunting and gathering to today. This is the human climate niche , which has the major band between 11 - 15 ℃ (average 13 ℃) and a secondary band between 20 - 25 ℃ . This secondary band corresponds to the region that receives the Indian Monsoon (hence, important!). Following an RCP8.5 and SSP3 scenario, the results indicate that the areas that experience Mean Annual Temperatures (MAT) of ~13 ℃ (the major band) today will experience MAT of ~ 20 ℃ by the year 2070. For the secondary band, there is a rather alarming result. To quote: " Specifically, 3.5 billion people ...