The intensification of heat stress poses severe risks to global populations, particularly in subtropical regions. Vulnerable groups, including the elderly, children, and those with pre-existing health conditions like cardiovascular disease and asthma, are at heightened risk. Nighttime heat stress exacerbates health issues by reducing recovery time, leading to increased mortality rates. Regions such as southern North America, southern Europe, and parts of Africa are experiencing up to 50 additional days of extreme heat stress annually. The study also notes that extreme heat stress now occurs 2.5 times more often in Europe and South America, and nearly twice as often in North America, highlighting the widespread impact of climate change.