The Impact of Urban Heat Islands in Europe
The summer of 2025 has once again been marked by a series of intense heatwaves that have affected large parts of Europe. These extreme weather events have had the most severe impact on urban areas, where temperatures can be significantly higher than in surrounding rural regions due to the Urban Heat Island (UHI) effect.
According to Niels Souverijns, a climate expert at VITO in Belgium, the UHI effect causes cities to be two to four degrees warmer than their rural counterparts. Data from the European Commission’s Joint Research Centre highlights that surface temperatures in cities can be as much as 10-15°C higher during the summer months. This is a major concern, especially since almost 40% of Europe’s population lives in cities, with around 70% residing in urban areas.
Health Risks and Vulnerable Populations
The UHI effect poses serious health risks, particularly for vulnerable groups such as the elderly and young children. A study by the NOVA National School of Public Health in Portugal found that hospital admissions increased by 18.9% on days when heatwaves occurred. This strain on healthcare systems underscores the urgency of addressing the issue.
Moreover, the phenomenon is more pronounced at night, as people do not cool down properly, leading to negative health effects. For individuals with pre-existing conditions like respiratory or cardiovascular diseases, this can be particularly dangerous.
Causes of the Urban Heat Island Effect
The UHI effect is driven by several factors, including the widespread use of heat-absorbing materials such as asphalt and concrete. These materials retain heat during the day and release it at night, contributing to higher urban temperatures. Wim Thiery, a climate scientist at VUB, explained that tall buildings and narrow streets also play a role by trapping heat and limiting natural wind flow.
In many cities, poorer urban areas are disproportionately affected due to dense and unregulated development. These areas often lack green spaces, proper insulation, and access to cooling options. In contrast, wealthier neighborhoods tend to have more trees and parks, highlighting the socio-economic dimensions of the problem.
Green Solutions for Urban Cooling
Experts emphasize that cities must adopt measures to counteract the UHI effect. This includes creating wind corridors, designing green roofs and facades, planting more vegetation, and using water more effectively. According to Souverijns, “we have to redesign cities to remove as much concrete as possible.”
The Brussels region is particularly vulnerable to heatwaves, with temperature differences of up to 10°C compared to rural areas. To address this, the City of Brussels provides residents with information on how to stay safe during hot days, including interactive maps that show drinking water points, shaded areas, and other cooling resources.
Adaptation and Mitigation Strategies
While adaptation efforts are crucial, experts agree that they alone are not sufficient. Thiery noted that the impact of localized measures like tree planting is limited, as nearby areas may still experience higher temperatures. He stressed the importance of mitigation strategies, such as reducing CO2 emissions, to prevent the situation from worsening.
Souverijns echoed this sentiment, warning that without significant emission reductions, cities could face a “tsunami of heat” that makes them increasingly uninhabitable. The City of Brussels is focusing on sustainable building renovations, which account for 60% of regional CO2 emissions, as well as plans for sustainable mobility and energy use.
Long-Term Goals and Challenges
The region aims to reduce CO2 emissions by 55% by 2030 and achieve climate neutrality by 2050. However, experts warn that failure to reach zero emissions will lead to dire consequences. Already, cities in India and equatorial countries are experiencing similar challenges, with residents struggling to cope with extreme heat.
Addressing the UHI effect requires a comprehensive approach that combines adaptation, mitigation, and long-term planning. As climate change continues to intensify, the need for innovative solutions to make cities more livable becomes ever more urgent.