5 things you should know about extreme heat
Extreme heat is a growing challenge across Europe. In the first half of this year, the continent has already experienced two major heatwaves. Temperatures in June reached 41°C for 100 million Europeans, and all-time heat records were beaten in thousands of cities.
Europe is warming faster than any other region, and heatwaves are affecting people’s health, ecosystems, infrastructure and the economy. Understanding the science behind extreme heat and the solutions that can help us adapt is essential. The specific solutions will depend on local circumstances and are best identified by national and local authorities.
The EU’s Directorate-General for Climate Action collected five things to know about extreme heat, and how we can work together to prevent it and react to it.
1. Heatwaves are getting longer, hotter, and more frequent
Heatwaves are not new, but they are getting worse – longer, hotter and more frequent. In fact, 23 of the 30 most severe heatwaves recorded since 1950 have occurred since 2000. Europe has been warming at more than twice the global average.
Scientists around the world analyse measurements collected from weather stations, ships, buoys and satellites. Organisations such as the Copernicus Climate Change Service, NASA, NOAA and the UK Met Office all track global temperatures independently. Each uses its own methods and datasets, yet they all identify the same long-term warming trend.
2. Extreme heat is Europe’s deadliest weather hazard
When thinking of extreme weather, you might picture flooded streets, storm damage or raging wildfires. Yet heat is the real killer. It claims more lives than floods, storms and wildfires combined. Around 95% of fatalities linked to weather- and climate-related extremes in Europe are caused by heat.
Unlike other disasters, though, heat often leaves no visible trail of destruction. Rather than causing immediate injury, it often worsens existing cardiovascular, respiratory and other chronic conditions. Its impacts are far less visible.
One of the threats is the growing number of “tropical nights”, when temperatures do not fall below 20°C. Normally, cooler night-time temperatures allow the body to release the heat accumulated during the day and recover. When nights remain warm, this natural cooling process is disrupted, increasing the risk of heat stress. High temperatures also have a negative effect on people’s performance at work or in their studies.
High humidity can make matters worse
by making it harder for sweat to evaporate, reducing the body’s ability to cool itself. Scientists use the wet-bulb temperature to describe this combined effect of heat and humidity.
In 2022 alone, an estimated 70,000 people died from heat across Europe. Older people, young children, people with underlying health conditions and those working outdoors are among the most vulnerable.
Early estimates from this year’s June heatwave already suggest a substantial human toll. A rapid modelling study indicates that the extreme temperatures may have claimed more than 20,000 lives. According to the analysis, between 22 and 28 June there were likely over 5,000 excess deaths in France, 4,500 in Germany, more than 3,000 in Spain, 2,700 in Italy, 1,070 in Poland, and 862 in the UK.
Because heat is often recorded as a contributing factor rather than the immediate cause of death, heat-related deaths cannot simply be counted from death certificates. Instead, scientists combine mortality records with temperature observations to calculate excess mortality, which is the number of deaths above what would normally be expected for a given place and time of year.
3. This problem is caused by humans, and can be fixed by them too
Greenhouse gas emissions from human activities, primarily the burning of fossil fuels, are driving climate change. As the planet warms, the likelihood and severity of extreme heat increase.
But the future is not predetermined. By reducing greenhouse gas emissions, we can limit future warming and the risks associated with extreme heat. At the same time, investing in clean technologies, renewable energy, and energy efficiency can strengthen Europe’s competitiveness, reduce our dependence on imported fossil fuels and support a more resilient economy.
Even with ambitious climate action, Europe will continue to experience more frequent and intense heatwaves in the coming decades. Adapting to these changes is therefore essential. Climate-resilient buildings, passive cooling, greener cities, nature-based solutions, heat-health action plans and early warning systems can all help reduce the impacts of extreme heat.
The upcoming Integrated Climate Resilience Framework will help bring these efforts together and strengthen Europe’s resilience to a changing climate; we should automatically embed resilience to climate change in all our planning.
4. Air conditioning can help, but it cannot solve extreme heat alone
During periods of dangerous heat, air conditioning can be necessary. It helps protect people from heat-related illness and reduces health risks when temperatures become extreme. It can be particularly beneficial for vulnerable people and buildings – for example in schools, hospitals and care homes for the elderly.
As Europe adapts to a warmer climate, air conditioning will be part of the solution. However, relying on air conditioning alone risks creating a vicious circle. As temperatures rise, demand for cooling increases, leading to higher electricity consumption and, in many cases, adding greenhouse gas emissions.
Air conditioners also release heat from buildings into surrounding streets.
This is particularly problematic in densely built urban areas, where it reinforces the urban heat island effect. One modelling study using Paris as an example found that widespread air conditioning could increase outdoor temperatures by up to 4°C. This has a disproportionate effect on those that cannot afford air conditioning, and it raises the energy costs for everyone.
To make optimal use of air conditioning, it is important to understand why a given building is overheating. There are measures that may be able to mitigate the situation and bring temperatures to comfort levels, for example solar shading, insulation or ventilation. If those are not sufficient, air conditioning can become necessary. Even in these cases, it should be combined with mitigation measures to help reduce the size of the equipment and installation and running costs and complemented by systemic measures like better urban planning.
5. Trees are the most effective natural cooling systems
Some of the most effective tools for cooling our cities are already offered by nature. Trees, parks, wetlands and other nature-based solutions provide shade while cooling the surrounding air through evapotranspiration, the natural process by which plants release water vapour into the atmosphere. Keeping cities cool also depends on how we design them. Reducing heat-absorbing surfaces like concrete or asphalt and weaving nature into urban planning makes cities more resilient to extreme heat. A study covering more than 600 European cities found that urban trees reduce air temperatures by an average of 0.8°C, with even greater cooling effects in some locations.
Measures such as planting more trees, expanding green spaces, installing green roofs and walls, introducing water features, using lighter reflective materials and designing buildings that stay cool naturally can all help reduce urban temperatures during heatwaves. Rethinking streets and public spaces to make more room for people and greenery can further enhance these cooling benefits.
Beyond cooling,
these measures improve air quality, support biodiversity, reduce flood risk and create healthier, more liveable cities. Many nature-based solutions also contribute to climate mitigation by storing carbon and reducing the need for energy-intensive cooling.
As Europe adapts to a warmer climate, investing in nature-based solutions may be one of the cheapest and most effective ways to keep communities cool, healthy and resilient.
Extreme heat is becoming a bigger part of life in Europe, influencing how people live, work and build their cities. Understanding the science, recognising the risks, and combining technology with nature-based solutions will be key to keeping people safe as temperatures continue to rise.
Ultimately, while adapting to more frequent heatwaves is becoming increasingly important, reducing greenhouse gas emissions remains the most effective way to limit the risks of extreme heat in the future.
Photo: Unsplash