Human climate niche

The human climate niche is the ensemble of climate conditions that have sustained human life and human activities, like agriculture, on the globe for the last millennia. The human climate niche is estimated by calculating the human population density with respect to mean annual temperature. The human population distribution as a function of mean annual temperature is bimodal and results in two modes; one at 15 °C and another one at ~20 to 25 °C. Crops and livestock required for sustaining the human population are also limited to the similar niche conditions. Given the rise in mean global temperatures, the human population is projected to experience climate conditions beyond the human climate niche. Some projections show that considering temperature and demographic changes, 2.0 and 3.7 billion people will live in out of the niche by 2030 and 2090, respectively.