Up to 3bn out of the projected world population of about 9bn could be exposed to temperatures on a par with the hottest parts of the Sahara by 2070, according to research by scientists from China, US and Europe.

However, rapid reductions in greenhouse gas emissions could halve the number of people exposed to such hot conditions. “The good news is that these impacts can be greatly reduced if humanity succeeds in curbing global warming,” said study co-author Tim Lenton, climate specialist and director of the Global Systems Institute at Exeter university.

The report highlights how the majority of humans live in a very narrow temperature band of 11C-15C (52F-59F). Researchers noted that despite all innovations and migrations, people had mostly lived in these climate conditions for several thousand years.