Prolonged exposure to extreme heat has serious repercussions on health. It can overwhelm the body’s ability to regulate temperature, increasing the risk of dehydration, heatstroke, cardiovascular stress, and even death – particularly among the elderly, infants and outdoor workers.
And the 2025 Lancet Countdown report – which tracks the health impact of climate change and is widely regarded as a key scientific reference on the issue – warns that the health risks posed by rising global temperatures are now more severe than ever.
“Throughout last year,152 record-breaking extreme weather events were registered across 61 countries, and life-threatening, extreme heat events are becoming more intense than previously predicted,” the report stated.
“The climate crisis is a health crisis. Every fraction of a degree of warming costs lives and livelihoods,” said Jeremy Farrar, assistant director-general for Health Promotion and Disease Prevention and Care at the World Health Organization (WHO).
The report found that heat-related mortality has increased by 23% worldwide since the 1990s, with an average of around 546,000 deaths each year.