Extreme heat is now a greater threat to human life than floods, earthquakes and hurricanes combined, according to the Reinsurance News website, citing the recently published SONAR 2025 report by global reinsurer Swiss Re (Zurich, Switzerland). The annual report, which tracks emerging risks affecting insurers and global systems, considers extreme heat to be a major concern not only because of its impact on health, but also across industries and infrastructure.
According to Swiss Re, up to half a million people die each year as a result of extreme heat, more than the combined death toll from other major natural catastrophes.
“Extreme heat was previously considered an ‘invisible hazard’ because its effects are not as obvious as with other natural disasters. Given the clear trend towards longer and hotter heat waves, it is important that we highlight the true cost to human life, our economy, infrastructure, agriculture and health system,” emphasises Jérôme Egeli, chief economist at Swiss Re Group, quoted in the report.
Data confirms this shift. July 2024, for example, saw three of the hottest consecutive days on record globally. In the United States, heat waves have tripled since the 1960s, with each wave now lasting a full day longer and nearly one degree Celsius higher.
The impact on public health is becoming increasingly evident, with some 480,000 deaths recorded each year due to extreme heat. In addition, it can lead to exhaustion, heat stroke and organ failure, as well as aggravate chronic cardiovascular and respiratory diseases. The most vulnerable categories are the elderly and pregnant women.
Swiss Re points out that the consequences go far beyond health. in particular, heat waves combined with strong winds dramatically increase the likelihood of forest fires. Over the past decade, for example, insured losses related to wildfires worldwide have reached nearly $78.5bn.
The report also identifies critical exposure points in key industries. For example, the telecommunications sector is vulnerable to disruption as rising temperatures threaten the functioning of data centres and physical networks, including terrestrial cables.