Future of the human climate niche

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. The authors demonstrate that depending on scenarios of population growth and warming, over the coming 50 years, 1 to 3 billion people are projected to be left outside the climate conditions that have served humanity well over the past 6,000 years. Absent climate mitigation or migration, a substantial part of humanity will be exposed to mean annual temperatures warmer than nearly anywhere today.

So far, the scope for local adaptation has been the dominant focus for analyses of possible responses to a changing climate, despite a striking lack of realized adaptation in most regions. The authors argue that it is not too late to mitigate climate change and to improve adaptive capacity, especially when it comes to boosting human development in the Global South. Looking at the benefits of climate mitigation in terms of avoided potential displacements may be a useful complement to estimates in terms of economic gains and losses.