Source: UNISDR Disaster Risk Reduction
In recent years, extreme heat has become the leading cause of reported weather-related deaths.
The number of people exposed to extreme heat is growing in all world regions, with deadly implications: heat-related mortality for people over 65 years of age increased by approximately 85% between 2000–2004 and 2017–2021.
Between 2000 and 2019 studies show that approximately 489,000 heat-related deaths occurred annually, with 45% of these in Asia and 36% in Europe. Of these, an estimated 61,672 heat-related excess deaths occurred in the summer of 2022 alone.
However, many heat action plans remain focused on response rather than transformation, with limited emphasis on reducing risk before extreme heat events occur. Compounding this challenge, extreme heat is still not widely recognized as a disaster by many countries, leading to significant underreporting and masking the true scale of its impacts.
A heatwave is a marked warming of the air, or the invasion of very warm air, over a large area; it usually lasts from a few days to a few weeks (WMO, 1992).
Extreme heat is also a serious environmental hazard and a major risk to people’s health at work, which puts at risk around 2.4 billion workers—70% of the planet’s working population
Extreme costs of extreme heat
The costs of extreme heat are also increasing. Between 2000 and 2023, extreme temperature events caused economic damages close to USD 73 billion. The most notable peaks were in 2003 and 2008, when total costs of USD 20.7 billion and USD 31 billion were recorded. In 2021, extreme heat led to when USD 6.3 billion in damages occurred in North America alone.
The indirect impacts of extreme heat not only disrupt everyday life, but also lead to long-term economic and social costs. Extreme heat events in Europe contributed to an extra USD 2.8 billion in annual losses due to increased hospital admissions and diminished labor productivity. Extreme heat increases energy demand, reduce work productivity and strain healthcare systems due to a rise in heat-related illnesses. In urban areas, extreme heat events cause maintenance and repair costs to surge by 12–15%, resulting in an extra cost burden of about USD 4.5 billion annually in major cities, posing significant challenges for sustainable urban planning.
On the agriculture sector, the past 30 years have seen an estimated loss of USD 3.8 trillion in crops and livestock production due to disaster events, translating to an average annual loss of USD 123 billion per year, or 5 percent of global agricultural GDP.
According to IPCC predictions, with 1.5°C of warming, 67 cities will experience over 150 days a year of temperatures greater than 35°C – a figure rising to 197 cities with 3°C of warming.
The agricultural sector, where over 940 million people – including many of the world’s poorest citizens – earn their livelihoods, is already being disrupted by the effects of extreme heat as higher temperatures push workers to the limits of their endurance and threaten crops with drought. Without resilience building, this can result in lost labour, smaller harvests and higher prices for consumers.
During the 2012 heatwave in the United States, maize yields dropped by 13%, resulting in a sharp increase in global corn prices because the country supplies 40% of global production. In the short term, the food price volatility resulting from these weather events puts low-income countries, particularly those with high crop import dependency ratios, at risk of food insecurity.
In some areas of India, for example, the effects of shifting weather conditions on agriculture and other sectors are projected to result in a 9% fall in living standards by 2050 if no action is taken, affecting hundreds of millions of people and reversing vital progress in terms of poverty reduction.
For the big five major hazard groups (earthquakes, floods, storms, drought and heat) the recorded direct economic costs came to over USD 195.7 billion in 2023, constituting 0.015% of global GDP that year.
Earthquakes account for over a quarter (25.6%) of global economic disaster losses.
Recent data suggests that floods account for up to 35–40% of weather-related disaster occurrences.
In some regions, storms account for up to 35% of total recorded disaster costs, driven by high winds, storm surges, and heavy rainfall.
Droughts often unfold slowly, but with far-reaching impacts on agriculture, water supplies, and economic stability.
In recent years, extreme heat has become the leading cause of reported weather-related deaths.
As climate change continues to escalate, the number of recorded disasters and their associated costs rise correspondingly.