The poorest countries will suffer the most, but it also has serious consequences for the rich.

According to studies "Greatly increased risk to humans as a result of empirically determined lower tolerance to humid heat stress", published in Proceedings of the National Academy of Sciences (PNAS) by a team of researchers from Pennsylvania State University and Purdue University. “If global temperatures rise by 1 degree Celsius or more above current levels, billions of people each year will be exposed to such extreme heat and humidity that they will be unable to cool themselves naturally. The results of a new study funded by the National Institute on Aging, NASA, and the National Science Foundation suggest that “global warming beyond 1.5°C above pre-industrial levels will be increasingly devastating to human health across the planet.” Penn State reminds us that “People can only tolerate certain combinations of heat and humidity before their bodies start to experience heat-related health problems, such as heat exhaustion or heart attacks. As climate change raises temperatures around the world, billions of people could be pushed beyond these limits.”