Extreme heat: What to know about the deadliest climate risk of our time

Extreme heat is identified as the deadliest climate risk, causing 489,000 annual deaths and projected productivity losses of $2.4 trillion by 2035. The document highlights the vulnerability of older adults, outdoor workers, and urban populations affected by the 'urban heat island' effect. It argues for a shift from reactive disaster funding to proactive investments in nature-based solutions, early warning systems, and worker protections.

• Extreme heat is the most lethal climate risk, resulting in 489,000 deaths every year, which exceeds the combined annual death toll from wildfires, earthquakes, hurricanes, and floods.
• Global warming is accelerating, with surface temperatures rising by approximately 0.26 °C per decade. In 2024, the average surface temperature reached 1.55°C above pre-industrial levels, the warmest on record.
• Heat-related mortality has increased significantly for older populations, with deaths among adults aged 65 and older rising by an estimated 85% since the 1990s. A 2022 study of 35 European countries found 61,672 heat-related deaths between May 30 and September 4, noting that women experienced 56% more deaths than men.
• Urban areas act as 'heat traps' due to the urban heat island effect, where building materials and city geometry can make cities 10-15°C hotter than rural areas. This risk is compounded by increasing urbanization, with 68% of the population expected to live in cities by 2050.
• The economic impact of heat exposure is projected to reach $2.4 trillion in annual productivity losses by 2035. Currently, 88% of weather-related disaster funding is spent reactively rather than on proactive resilience.
• Nature-based solutions can significantly lower temperatures: botanical gardens and wetlands can reduce temperatures by approximately 5.0°C and 4.9°C respectively, while general green spaces can reduce them by 1.0 °C to 4.0 °C.

APA

Crowfoot, T. (2025). Extreme heat: What to know about the deadliest climate risk of our time. World Economic Forum. https://www.weforum.org/stories/climate-action/what-to-know-about-extreme-heat/

Chicago

Crowfoot, Tom. Extreme heat: What to know about the deadliest climate risk of our time. World Economic Forum, 2025. https://www.weforum.org/stories/climate-action/what-to-know-about-extreme-heat/.

Wikipedia

{{cite report |last1=Crowfoot |first1=Tom |title=Extreme heat: What to know about the deadliest climate risk of our time |publisher=World Economic Forum |date=30 July 2025 |url=https://www.weforum.org/stories/climate-action/what-to-know-about-extreme-heat/ |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{crowfoot2025extreme, author = {Crowfoot, Tom}, title = {{Extreme heat: What to know about the deadliest climate risk of our time}}, institution = {World Economic Forum}, year = {2025}, month = jul, url = {https://www.weforum.org/stories/climate-action/what-to-know-about-extreme-heat/}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }