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Latin America and the Caribbean cities are the development engine of the region. Home to almost eighty percent of all residents, they serve as the base for government institutions and are home to an immense number of cultural assets and productive activities. Because of this great concentration of people and resources, negative impacts on cities’ well-being have serious implications for the prosperity of the region. Among these, excessive heat and fires have become one of the most endemic and disruptive impacts cities face.
Urban Heat Island
Cities face higher temperatures than their surroundings, an effect known as the Urban Heat Island (UHI). This happens because roads, buildings, and other built infrastructure absorb, retain, and reemit heat at a greater rate than the natural environment, while clusters of tall buildings reduce ventilation and trap heat. Additionally, human activities that generate heat are highly concentrated. In the eight largest cities in Latin America and the Caribbean, the UHI effect leads to temperatures that are 3°C to 8°C higher than those in surrounding areas (Sarricolea et al., 2019) Under the worst scenario, South America’s largest cities will see five to ten times more extremely hot days by 2050, with temperatures that used to occur less than twenty days a year occurring up to six months annually (Kephart et al., 2022).
Extreme heat disrupts economic activity, increases health risks, and promotes the propagation of pathogens transmitted by food, water, insects, or other animals. These impacts are particularly harmful to elders and children and to residents living in low-quality housing lacking proper insulation and ventilation systems.
Fires
Higher temperatures increase the incidence of wildfires that affect urban areas. From 2015 to 2018, 152 out of 196 countries around the world saw a rise in the average annual number of days people were exposed to fires compared to 2001–2004 (Watts et al., 2021). Wildfires cause deforestation, increase susceptibility to landslides, and disrupt air transportation by reducing visibility. In addition to the injuries and deaths they inflict directly, they can be harmful to health, exposing large numbers of people to particulate-matter air pollution that can lead to eye and respiratory illnesses.
Fires can start on the outskirts of cities and then spread across them, moving especially quickly through dwellings that are built close together in informal settlements. In fact, the large majority of deaths and injuries related to urban fires occur in low- and middle-income countries, and the risk of fire resulting in trauma, injury, or death is particularly high in low-income and informal settlements. In these locations, population density is high, housing materials are often flammable, access to safe power sources is unreliable or nonexistent, and, sometimes, fire services are unable to reach the sites that are burning.
What Can Be Done to Reduce UHI and Prevent Urban Fires?
Make Cities Greener. Urban parks can substantially reduce ambient temperatures and mitigate the UHI effect by providing shade and through transpiration. It is estimated, for instance, that an optimally designed urban park of 2,500 square meters in Mexico City can reduce the temperature by 5.3°C (Ramos-Palacios et al., 2024). Trees and shaded areas can also be incorporated into bike lanes and avenues. Similarly, green roofs can provide crucial relief for those who do not have access to cooling, and they can reduce energy consumption for those who do. During the Favela Green Roof pilot program in Rio de Janeiro, Brazil, homes with green roofs were up to 20°C cooler indoors during peak heat than those with traditional roofs (Oliver et al., 2021).
Upgrade Urban Codes. Building codes can promote the use of certain materials, passive cooling designs, and insulation metrics to regulate heat inside buildings. To be effective, codes should be tailored to the specific risk levels of each location and include a streamlined process to update them dynamically as new technologies and needs emerge. It should also be noted that enforcement is a challenge, particularly in LAC cities where a significant percentage of building construction is informal. When building anew is not an option, retrofitting existing units and building fire-protective barriers may be needed.
Inform and Give Warnings. Cities can use information and communication strategies to improve responses to emergencies. This is where early warning systems come into play. They allow prompt and orderly evacuations and help households and authorities prepare for disasters. Developing early warning systems and evacuation routes can help citizens avoid the devastating effects of fires, protecting people’s health and assets. Just twenty-four hours’ warning of a coming heatwave can cut the ensuing damage and avoid material losses.
Coordinate and Join Forces. Better metropolitan coordination will contribute to lowering heat and fire risks effectively. For example, the forest management needed to reduce wildfire risks in cities may depend on a different jurisdiction or a central government institution rather than the local urban planning authority. Private sector organizations, community groups, and other local players can come together, share effective practices, monitor progress, and coordinate actions to improve risk management at a regional level.
Conclusion
Heat and fire will continue to challenge cities. However, much can be done to reduce their negative impacts on the well-being of cities. Increasing green areas, upgrading urban codes, improving disaster management, and enhancing metropolitan coordination can empower local governments and communities to address these issues. It is imperative that cities proactively tackle these challenges to enable people to lead healthier and more productive lives.
To further deepen the identification and mitigation of Urban Heat Islands, the IDB has developed tools and studies that serve as valuable references. One such tool is URSA, an intelligent software designed to identify and analyze thermal effects in urban environments, enabling cities to develop more effective strategies to combat extreme heat (see blog post: How to Identify Urban Heat Islands: Discover URSA, the IDB’s New Intelligent Software). Additionally, studies such as the one conducted in Montevideo, Uruguay, have demonstrated the importance of mapping these phenomena to improve urban planning and ensure more resilient and sustainable cities in the future (Identifying Heat Islands in Montevideo for Sustainable City Planning). These articles, available on the IDB’s Sustainable Cities blog, highlight the need to integrate technology, urban planning, and public policies to address climate challenges in Latin America and the Caribbean.
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