Heatwaves, one of the most significant consequences of climate change, are becoming increasingly frequent and intense, posing a serious threat to global populations. Urban areas, with their dense infrastructure, are particularly susceptible to extreme heat, affecting over 1.7 billion people worldwide.
In fact, nearly half of the world’s 10,000 cities have experienced heightened heat exposure in the past 40 years. In response, a recent policy brief from the Joint Research Centre (JRC) outlines key strategies, best practices, and policy tools designed to help local authorities in EU cities mitigate the impacts of extreme heat.
This comprehensive guide aims to equip cities with the knowledge needed to manage rising temperatures and protect public health and well-being.
Read More: Managing Extreme Heat: Strategies to Combat Urban Heat Islands and Keep Cities Cool
The Impact of Heat Extremes and Urban Heat Islands (UHI)
As climate change accelerates, heat extremes and urban heat islands (UHI) are becoming more prevalent, posing significant challenges to cities worldwide. Heatwaves, defined by prolonged periods of excessively high temperatures, exacerbate urban overheating and contribute to the UHI effect.
This phenomenon occurs when cities experience substantially higher temperatures than surrounding suburban or rural areas. On average, urban centers affected by UHIs are 4-6°C warmer, with temperature spikes reaching up to 10°C above neighboring regions.
These elevated temperatures have far-reaching consequences, including increased health risks, higher energy demand, and a decline in overall urban quality of life. Addressing the UHI effect is critical to ensuring the sustainability and livability of urban environments in the face of climate change.
Why Are Our Cities Becoming Hotter?
Urban areas are particularly prone to elevated temperatures due to several factors. The prevalence of impervious surfaces, such as roads and buildings, absorbs heat during the day and releases it at night, intensifying the urban heat island effect.
Additionally, the high density of people and infrastructure, including transportation systems, contributes further to heat generation. The lack of sufficient green spaces, waterways, and limited ventilation exacerbate the situation, reducing natural cooling mechanisms.
The impact of extreme heat extends beyond discomfort—it poses serious health risks. In addition to heat-related illnesses like dehydration and heatstroke, the UHI effect traps pollutants, worsening air quality and leading to long-term health issues.
Vulnerable groups—such as low-income communities, the unemployed, the homeless, children, the elderly, and those with chronic health conditions—are disproportionately affected. Moreover, the increase in energy demand to combat heat further enlarges cities’ ecological footprints.
Strategies to Combat Extreme Heat
The Joint Research Centre (JRC) policy brief advocates for a comprehensive approach that combines both mitigation and adaptation strategies to address extreme heat. This involves reducing greenhouse gas emissions while enhancing resilience to heatwaves. Many cities are already embracing these actions through initiatives such as the Global Covenant of Mayors for Climate & Energy.
Case Study: Murcia, Spain
A notable example is Murcia, Spain, which earned the Covenant of Mayors Spotlight Award for its efforts in tackling urban overheating. The city’s innovative approach included resurfacing dark asphalt roads with lighter-colored materials to reflect sunlight, significantly lowering surface temperatures. This measure was part of a broader set of 61 actions to combat extreme heat.
Best Practices for Urban Heat Mitigation
The JRC policy brief identifies a range of best practices to help local authorities mitigate the effects of urban heat. These include:
Enhancing Green Infrastructure: Promoting green walls, roofs, and increasing tree coverage, which has been shown to lower air temperatures in urban environments. In a study of over 600 European cities, urban trees reduced air temperatures by an average of 0.8°C.
Incorporating Water Features: Introducing water features and improving water accessibility, such as providing drinking water and incorporating flowing water in public spaces to cool the environment.
Retrofitting Buildings: Installing insulation, shutters, and using reflective materials like white paint on streets and buildings to reduce heat absorption.
Promoting Urban Farming: Increasing green space and food production through urban farming initiatives.
Implementing Healthcare Measures: Establishing heat warning systems, providing shelter locations, and ensuring access to drinking water during heatwaves.
Positive Impact on Society
This research provides valuable insights to local, regional, and national authorities, enabling them to develop practical and cost-effective policies for managing extreme heat as global temperatures continue to rise.
By collaborating with partners such as the Covenant of Mayors to implement these strategies, the JRC is contributing to enhancing quality of life and fostering societal well-being. These efforts not only address the challenges posed by heat extremes but also support the long-term resilience of communities.
Frequently Asked Questions (FAQs)
What is the Urban Heat Island (UHI) effect?
The Urban Heat Island (UHI) effect refers to the phenomenon where urban areas experience significantly higher temperatures than surrounding suburban or rural regions. This is due to the concentration of buildings, roads, and infrastructure, which absorb and retain heat, leading to higher surface temperatures in cities.
Why are cities more susceptible to extreme heat?
Cities are more vulnerable to extreme heat due to factors such as the abundance of impervious surfaces (roads and buildings), high population density, limited green spaces, and poor ventilation. These elements trap heat and reduce natural cooling processes, like wind and evaporation, making urban areas hotter than their rural counterparts.
How can cities mitigate the impacts of extreme heat?
Cities can mitigate the impacts of extreme heat by enhancing green infrastructure (e.g., green walls and roofs), increasing tree cover, incorporating water features, retrofitting buildings with reflective materials, and implementing urban farming. Additionally, effective healthcare measures, such as heat warning systems and accessible cooling shelters, can protect vulnerable populations.
What role does the JRC play in managing extreme heat?
The Joint Research Centre (JRC) provides research, recommendations, and policy guidance to help local, regional, and national authorities develop effective strategies for managing extreme heat. Through partnerships with initiatives like the Covenant of Mayors for Climate & Energy, the JRC supports the implementation of cost-effective solutions to improve urban resilience to heat extremes.
What are the benefits of reducing urban heat?
Reducing urban heat can lead to numerous benefits, including improved public health, enhanced energy efficiency, better air quality, and increased livability in cities. It also helps reduce the risk of heat-related illnesses, such as heatstroke and dehydration, particularly for vulnerable populations like children, the elderly, and low-income communities.
How can green spaces help reduce urban heat?
Green spaces, including trees, parks, and urban gardens, provide shade and release moisture into the air, cooling the environment through evapotranspiration. Research shows that urban trees can lower air temperatures by an average of 0.8°C, contributing to more comfortable and sustainable urban living conditions.
Conclusion
As global temperatures continue to rise, addressing extreme heat in urban areas has become an urgent priority. The Urban Heat Island effect, compounded by dense infrastructure and limited natural cooling, poses serious risks to public health, energy systems, and overall urban resilience. The Joint Research Centre’s policy brief offers a vital roadmap for local authorities, outlining practical, cost-effective strategies to both mitigate and adapt to these challenges.
