Scientists are raising concerns about the growing scale and frequency of extreme heat events, warning that prolonged periods of unusually high temperatures are increasingly affecting communities, agriculture, infrastructure and ecosystems across the world.
A Reuters investigation published on October 20, 2026, examined the expansion of what it describes as “heat storms” — exceptionally large heatwaves that cover extensive areas of the planet.
Using global temperature data stretching back to 1960, the investigation found a striking change in the frequency of these events. Under its definition, heat storms are heatwaves that reach at least one per cent of Earth’s surface at their peak. The analysis estimated that such events averaged around five annually in the 1960s, compared with approximately 102 a year during the current decade.
The human cost of extreme heat
Extreme heat presents serious risks to human health, especially among older people, outdoor workers, children and individuals without access to cooling facilities.
High temperatures can contribute to dehydration, heat exhaustion and potentially fatal heatstroke. They can also make it difficult for workers to perform physically demanding tasks safely.
Schools, hospitals and transport systems may experience additional pressure during prolonged hot periods. In cities, densely built neighbourhoods can retain heat, making nights uncomfortable and limiting the body’s ability to recover from daytime temperatures.
The burden is often greatest among lower-income communities, where access to air conditioning, reliable electricity and well-insulated housing may be limited.
Agriculture and infrastructure under pressure
Heatwaves can also damage agricultural production by increasing evaporation and placing stress on crops and livestock.
When high temperatures coincide with inadequate rainfall, farmers may face declining yields, rising irrigation costs and shortages of pasture for animals.
Prolonged heat can dry vegetation and increase the conditions that allow wildfires to spread. Roads, railway tracks and electricity systems may also come under pressure when temperatures reach extreme levels.
The effects can extend beyond the areas experiencing the highest temperatures. Disruptions to food production and transport may contribute to higher prices in distant markets.
What is driving the trend?
Climate change is a central factor in the growing threat.
The burning of coal, oil and natural gas releases greenhouse gases that trap heat in the atmosphere. Reuters’ analysis found that the expansion of heatwaves has occurred alongside rising atmospheric carbon dioxide concentrations.
Natural climate patterns, including El Niño, can intensify heat events and influence where they develop.
However, individual heatwaves are shaped by several factors, and their local impacts depend on geography, infrastructure, preparedness and the vulnerability of affected communities.
Preparing for a hotter future
Governments can reduce the impact of extreme heat by improving early-warning systems, expanding access to shade and drinking water, protecting outdoor workers and designing buildings that remain cooler.
Cities can also invest in trees, green spaces and infrastructure that reduces heat retention.
Reducing greenhouse gas emissions remains essential to limiting future warming, while adaptation measures can protect lives against heat that is already occurring.
The growing scale of extreme heat shows why climate preparedness must be treated as a public-health, economic and infrastructure priority rather than solely an environmental issue.
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