How Extreme Heat and Humidity Are Pushing the Limits of Human Survival: QuickTake

The world touched a global record on July 3, the hottest day ever, as climate change raises temperatures. Heat waves are also more frequent and more acute. Factor in humidity, and extreme weather is already testing the limits of the human body. Last year, when blistering heat hit India, Pakistan, Bangladesh, Nepal and Sri Lanka, New Delhi recorded peaks of more than 49C (120F). This year, parts of India again hit sweltering pre-monsoon temperatures — grim news for power grids, crops and hundreds of millions of workers, though figures on fatalities remain unclear. Elsewhere, a punishing heat dome covered Texas and northern Mexico. Unusually hot and dry conditions are forecast into the summer in Europe as well.

Many reasons. People are more likely to dehydrate in high temperatures, increasing the risk of heart attack and stroke. Heat can worsen breathing problems, especially where pollution levels are elevated. Heat stress makes it harder for people to work and increases the likelihood of injuries. It’s hard to know exactly how many people die from heat each year; most go uncounted. There’s no official toll from the 2022 scorcher in India and Pakistan, but early tallies of about 90 deaths are almost certainly too low. Emerging economies suffer more than developed ones, as there tends to be little respite from the sun; most people work outside and few have effective cooling at home. Concrete and asphalt in urban settings can trap the heat, elevating overnight temperatures and contributing to heat stress. Women and seniors were found to be the most affected populations in one 10-year study of extremely hot weather events conducted in Hong Kong.