The world is currently on track for 2.7C of heating, meaning that 2 billion people will experience average annual temperatures above 29C by 2030. Up to 1 billion people might migrate to cooler places although areas remaining within the climate niche would still experience more frequent heatwaves and droughts. If global temperature continues to rise towards 2.7C, heating combined with growing global population will mean 2 billion people living outside the niche by 2030 and 3.7 billion by 2090. In countries with large populations and already warm climates most people will be pushed outside the human climate niche–India and Nigeria facing the worst changes. Urgent action to lower carbon emissions and keep global temperature rise to 1.5C would cut the number of people pushed outside the climate niche by 80%, to 400 million.
www.theguardian.com/environment/2023/may/22/global-heating-human-climate-niche