Heatwaves: Climate change is intensifying heatwaves, floods, wildfires and storms, but the human death toll from extreme weather is moving in different directions depending on the hazard and where people live, according to recent climate and disaster assessments.
The latest annual climate updates show that the past three years, 2023, 2024, and 2025, were the warmest on record, reinforcing warnings that rising temperatures are loading the dice toward more frequent and intense extremes. Scientists say that shift is most clearly evident in heat, which is increasingly becoming the deadliest weather risk, even as deaths from some sudden-onset disasters have declined over time.
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An analysis of data from EM-DAT, a widely used global disaster database, estimates that more than 2.3 million people died in weather-related events between 1970 and 2025. The tally for 2015–2025 was about 305,000 deaths, lower than roughly 354,000 in the previous decade. Researchers and disaster experts say the long-run decline reflects better preparedness, early warning systems, storm shelters, improved forecasting, and stronger emergency response, rather than weaker hazards.
Heatwaves remain the hardest category to count, and many public health researchers say deaths are underreported because heat often worsens existing heart, lung and kidney conditions rather than appearing as a direct cause on death certificates. Even so, recent figures point to a sharper rise in heat impacts. EM-DAT lists tens of thousands of heatwave deaths in recent years, including about 61,800 in 2022, around 48,000 in 2023, and roughly 66,800 in 2024. Public health monitoring efforts that model heat exposure and excess deaths suggest the true global toll is substantially higher, with average annual heat-related deaths estimated in the hundreds of thousands over the past decade.
By contrast, deaths linked to floods and storms in the EM-DAT database have generally trended lower in the last decade compared with earlier periods. Flood deaths for 2015–2025 were about 55,400, down from roughly 66,000 in the previous decade. Storm-related deaths fell more sharply, to about 36,700 in 2015–2025 compared with about 184,000 in the decade before that, although annual numbers can swing dramatically depending on single catastrophic events.
Insurers and disaster researchers caution that a downward trend in fatalities does not mean risk is easing. Munich Re, a major global reinsurer that tracks disaster impacts, reported around 17,200 deaths from natural disasters worldwide in 2025, higher than the roughly 11,000 recorded in 2024, though still below the longer-term averages it tracks. The firm and other experts say better protection is saving lives, but the underlying danger remains high as warming raises the odds of extreme rainfall, stronger heat events, and conditions that can fuel large fires.
The broad picture, experts say, is that preparedness can reduce fatalities, but only up to a point. As extreme events become more frequent and compound, heat followed by storms, or repeated flooding without time to rebuild, systems can be stretched, and vulnerabilities can grow, particularly in lower-income countries where infrastructure and health capacity are limited.