The earth is heating up, and city dwellers are feeling it the most.
Due to the “Urban Heat Island effect,” cities are quite literally hotter than their surroundings. High-heat cities, also called Urban Heat Islands (UHIs), don’t distribute heat evenly. Some areas within cities are even hotter than other areas. These neighborhoods, often low-income and formerly redlined, are under the most heat duress. (That they were redlined means they were systematic denied financial services, particularly mortgage loans, limiting their residents’ ability to build wealth.)
High-heat neighborhoods and their challenges arise due to several factors aside from redlining. One is the way buildings are constructed. For example, the use of heavy building materials like brick absorb heat within the structure rather than reflect it. Another is that there are more roads and other heat-trapping surfaces and less green space or waterfront. This means there are fewer places for people to escape the heat outdoors. Combined with few air-conditioned spaces for the public to use generally, it’s almost impossible to cool off.
High-heat neighborhoods can be 5 to 20 degrees hotter than surrounding neighborhoods. This poses very real threats to our health, both at the individual and community level. Simply put, high temperatures can be deadly. Heatwaves increase mortality rates, with 600 to 1,300 people dying of heat-related illnesses every year in the United States. Living in a high-heat neighborhood only increases that risk.
Exposure to high-heat conditions can lead to a number of health conditions. It becomes hard to sleep and people are at risk of dehydration and heat stroke. Heat also affects mental health. For example, exposure to heat for prolonged periods can make it hard to concentrate and cause mood and behavioral changes.
Residents of high-heat neighborhoods are oftentimes dually impacted. Aside from heat-related consequences, redlined communities can have worse air and water quality, more incomplete plumbing, and more noise pollution. Compounding with the effects of high-heat, all of these factors can cause high-heat neighborhoods to be particularly hazardous for health.
Structural issues aside, there are inequitable financial costs associated with heat as well. Generally, high-heat exposure leads to increased health care costs, impacting women, the elderly, low-income families, and ethnic minorities the most. More specifically, heat-related illness may result in expensive hospital stays, emergency department use, and medical transports. It can also come with a loss of income from missed work and expensive, long-term health complications.
At the community level, heat has consequences as well.
Violent crime is higher in hotter months, and there is a notable increase in suicides and hospital visits. High heat results in more school closures, especially if buildings don’t have air-conditioning. Missed school means a scramble by parents to find childcare, missed meals and worse educational outcomes for kids.
To cope with the high heat, increased use of air conditioning and fans creates stress on local energy grids and increases community energy expenses.
Given the dangers of UHIs, finding solutions is a pressing concern. Two of the most prominent proposed by scholars and climate activists are Green City and White City techniques.
Green City techniques incorporate nature-based solutions into urban planning and design with an aim to absorb heat. These strategies focus on increasing vegetation through initiatives such as urban forestry, green roofs, and green walls. Vegetation provides shade, absorbs heat, and releases moisture, ultimately cooling the environment. Green City techniques also include installing permeable surfaces like porous pavements instead of heat-retaining asphalt and concrete to allow water to soak into the ground and cool the area.
White City techniques look at reengineering roads, structures, and construction materials to make them more reflective of sunlight. When roofs and pavements are coated with special reflective materials, they reduce heat buildup. The goal is to minimize the amount of heat trapped and then radiated into the surrounding area. These strategies improve energy efficiency, reduce cooling costs, and enhance resident comfort.
Much theoretical work has been done to model Green City and White City techniques, helping policymakers make evidence-based planning decisions. Some cities, such as New York City and Boston, have conducted their own heat studies and are starting to implement a combination of these ideas.
The research is clear that heat impacts our health. Even though we need to learn more about the costs and benefits of Green City and White City techniques, they present a path forward. After all, our cities should be places of refuge, not suffering.
Research for this piece was supported by Arnold Ventures.
