3.5 billion people would live outside the climate "niche" in which humans have thrived for 6,000 years.
Unless greenhouse gas emissions decrease, according to a study published in the Proceedings of the National Academy of Sciences by archaeologists, ecologists and climate scientists, areas of the planet that are home to up to a third of humans will become as hot as the hottest parts of the Sahara in 50 years.
Climate niche
Human populations are largely concentrated in narrow climate bands, with the majority of people living in places where the average annual temperature is about 11-15 ° C and fewer people living where the average temperature is about 11-15 ° C. about 20-25 ° C.
As explained by Marten Scheffer of Wageningen University, who coordinated the research:
This surprisingly constant climate niche likely represents fundamental constraints on what humans need to survive and thrive.
However, in a scenario where emissions continue to rise unabated, the temperature experienced by the average person will have risen 7.5 ° C by 2070.
Currently, these climatic conditions are only experienced by 0.8% of the world’s land area, mainly in the warmer parts of the Sahara desert, but by 2070 the conditions could extend to 19% of the planet’s land area .
Rapid reductions in greenhouse gas emissions could cut the number of people exposed to such hot conditions by half.