It’s safe to say that a warming world is going to lead to greater discomfort for many of its inhabitants, but a new study out of Rutgers University is delving into the details of what this could look like come the end of the century. The team looked at how heat and humidity will combine to create heightened heat stress around the globe, concluding that it could affect more than four times as many people as it does today if current trends continue.
Were the planet to warm by 1.5° C (2.7° F) by the end of the century (a very conservative projection), the team calculates that heat stress would affect areas currently home to 500 million people. At 2° C (3.6° F) of warming that figure jumps to nearly 800 million, and at 3° C (5.4° F) of warming, a future many experts expect us to reach, an estimated 1.2 billion people would be affected by heat stress.
The team notes that this is four times the number of people affected by heat stress today, and 12 times as many as it would be were it not for industrial-era global warming. As for what this means for heat stress in a place like the Big Apple, the team says that New Yorkers could expect as many as 24 days each year that are comparable to the single worst day of the year today.
https://newatlas.com/environment/heat-stress-affect-billion-plus-people-climate-study/

