Overview
- Climate Central published an analysis on Wednesday showing global average dangerous humid-heat days rose from about 10 per year in the 1970s to roughly 23 per year in the 2020s, with the rise concentrated in the majority of analyzed cities.
- The Climate Central study uses wet-bulb temperature to measure combined heat and humidity and classifies conditions at or above 25°C wet-bulb as 'dangerous' because they raise the risk of heat illness.
- Climate Central attributes roughly two-thirds of current dangerous humid-heat days to human-caused climate change, saying warming from fossil-fuel emissions added most of the increase in 665 of 961 global cities analyzed.
- Penn State laboratory experiments released the same day found young, healthy adults hit critical core-temperature increases at about 31°C wet-bulb, lower than the previously cited theoretical 35°C limit and implying more people reach dangerous physiological stress sooner.
- The trend raises immediate risks for older adults, people with chronic illness, children, and communities with limited cooling access, and it will increase strain on hospitals, air-conditioning demand, and power grids while shaping public-health and adaptation planning.