Europe’s Soaring Heat and the Great Air Conditioning Dilemma

Much of Europe sweltered in August 2025 as a heat dome spread across the continent, pushing peak afternoon temperatures to over 40 degrees C (104 degrees F) in France and Spain. Meanwhile, parts of Greece, Turkey and Albania battled historic and devastating wildfires as high temperatures scorch the land.

Deadly summer heat waves have become the new norm in recent years for Europe, the world’s fastest-warming continent. With air conditioning in only 20% of the Europe’s buildings, city leaders face a pressing dilemma: how to keep people cool without worsening the climate crisis driving rising temperatures in the first place.

The cycle of rising heat, greater demand for cooling and growing emissions can be broken. Here, we look at data on Europe’s rising urban heat and explore how cities can adapt by pairing efficient, low-carbon air conditioning with long-term passive cooling solutions such as green roofs, reflective materials, tree planting and climate-smart building design.

An Increasingly Hotter Continent

The rising heat is being felt across the continent, from the typically warmer south to the usually cooler north. In June 2025, an unusually early heat wave made authorities close 200 schools across France, while parts of the Eiffel Tower were also shut due to the extreme heat. In July, temperatures in Athens soared to 44 degrees C (111 degrees F) for two days in a row, forcing the city to close the Acropolis, an UNESCO World Heritage site, due to dangerous heat levels.

It’s a scenario that could get worse as global temperatures continue to rise. Eight of the 10 countries across the world expected to see the biggest increase in extreme heat days — defined as days when the maximum temperature exceeds the historical average from the past 80 years — are in northwestern Europe, including Ireland, the UK, Germany and the Netherlands.

A WRI analysis of 69 of Europe’s largest cities – home to 165 million people, or about 22% of the continent’s population – found that the number of days at 35 degrees C (95 degrees F) or more could rise by 53% if global temperatures increase by 3 degrees C. Heat waves would also last longer under this scenario, making their impacts more severe.

The financial impact of heat is already clear. From 1980 to 2010, heat waves caused annual economic losses equivalent to 0.3% to 0.5% of GDP in several European cities, rising to more than 1% in southern Europe, mostly due to lost productivity. Without action to adapt, these losses could increase fivefold in the next 30 years.

Heat and Mortality

Extreme heat is a growing public health crisis — and, in many cases, a matter of life and death. During a single ten-day heat wave in June and July 2025, Milan, Barcelona and 10 other European cities recorded 2,300 heat-related deaths. More than half were directly linked to climate change-driven heat.

Each year, heat causes an estimated 175,000 deaths across Europe, according to the World Health Organization — a figure expected to rise sharply. One study projects an additional 2.3 million excess deaths in Europe by 2099 under the highest-warming scenarios. Even with adaptation measures, heat-related deaths are expected to increase in nearly all regions, with Eastern and Mediterranean Europe facing the greatest risks.

Vulnerable groups, including elderly adults, people with chronic illnesses, pregnant people and those living in poorly insulated or low-income housing, face the highest risk from extreme heat. In France, for example, record-breaking heatwaves in June and July 2019 caused around 1,500 excess deaths compared to the seasonal average, with about half of those who died aged 75 or older. 

Increasing Cooling Demand

Access to air conditioning in Europe remains among the lowest in the  world. The share of households with air-conditioning units by region in 2022 reveals that Europe (19%) lagged behind other regions, particularly North America (76%) and the Asia-Pacific (47%), in air conditioning adoption, falling well below the world average of 37%.

As Europe gets hotter and household incomes rise, demand for energy-intensive air conditioners is expected to grow. Between 2010 and 2019, the share of households with air conditioning increased from 14% to 20%.

Over the past decade, global energy use for cooling buildings has grown more than twice as fast as the total energy use in buildings. Without intervention, rising demand could drive up emissions in fossil-fuel dependent regions, deepening social inequality and putting additional pressure on power grids.

During the June and July 2025 heat wave, for example, electricity demand in some parts of Europe spiked by as much as 14%, peaking above typical winter levels and contributing to outages in countries like Italy. In Germany, energy demand during heat waves has risen more than fivefold since 1979.

As the need for cooling rises, some regions are particularly vulnerable. In northern and western Europe, for example, most buildings are designed to retain heat, making them ill-suited for increasingly hot summers, while in lower-income urban areas, high installation and operating costs can put air conditioning out of reach.

Without a faster clean energy transition, the rapid expansion of cooling could further accelerate climate change. By 2050, cooling alone could generate 6.1 billion tons of carbon dioxide emissions globally each year — nearly one-fifth of global emissions under many scenarios.

How to Cool Cities Down Without Driving Up Emissions

Passive cooling solutions — like reflective surfaces, natural shading, green roofs, ventilation and climate-smart building design — can reduce dangerous indoor heat, cut energy use and save lives. These approaches are essential as Europe faces longer, more frequent and severe heat waves. Air conditioners, a type of active or mechanical cooling, still play a critical role, particularly for vulnerable groups and for protecting food, medical supplies and key industrial processes. But it must be used efficiently, powered by clean energy and made accessible to all.

To prevent cities from locking into ever-rising cooling demand — and the climate and health risks that come with it — the first step is to reduce the amount of heat that buildings absorb and generate. This means blocking excess solar heat with shading, reflective glass and vegetation, while cutting internal heat from lighting, appliances and equipment. These baseline measures lower indoor temperatures before mechanical cooling is even needed.

The next step is to enhance natural ventilation and use building materials that store coolness or absorb excess heat, helping to stabilize indoor temperatures. Air conditioners should be used only when necessary, and then with energy-efficient, low-carbon systems targeted at vulnerable populations.

By tackling heat at its source, cities can reduce the need for air conditioning, cut emissions and protect public health without worsening the extreme heat that drives the problem.

Combining green urban infrastructure with energy efficiency measures can lower indoor temperatures by up to 2.9 degrees C. This could reduce global demand for cooling by 24%, avoid $3 trillion in air conditioning infrastructure costs and cut 1.3 billion tons of carbon dioxide emissions — roughly equal to Japan’s total greenhouse gas emissions in 2022. These joint energy-efficient and passive solutions are cost-effective, scalable and offer co-benefits such as better air quality, lower noise pollution and improved mental health.

Policy Choices for Cooler, More Resilient Cities 

Europe faces a growing heat challenge that remains underestimated and poorly reflected in current European policies. Relying heavily on air conditioning would risk locking cities into carbon-intensive infrastructure while deepening energy inequality.

So far, EU policies have focused on expanding renewable energy supply and improving the energy efficiency of air conditioners and other mechanical cooling systems — but not on incentivizing and mainstreaming passive cooling approaches. Meeting the extreme heat challenge requires a multi-level approach: passive cooling strategies must be scaled up and active cooling expanded only where necessary and only when powered by clean energy. 

Some European cities are already taking action to address extreme heat. Barcelona, Vienna, Paris and London have set up cooling centers, expanded urban greening and mandated climate-resilient building retrofits, including green roofs. In Austria, passive cooling measures alone could cut future cooling demand by 68% to 73%.  However, such initiatives currently remain the exception and must be scaled up to meet the growing challenge of hotter summers. Europe must now act on all fronts to cool its cities without fueling the climate crisis.

The priority is clear: with the right mix of planning, innovation and leadership, Europe can cool down without heating up. Cities are obviously key. But from their respective responsibilities — and within their budgetary and legislative capacities — regional, national and European governments should consider how best to support cities in helping residents cope with extreme heat. Cities should not face this challenge alone. 

Cover photo:  Image by nito/alamy