Environmental racism: Heat islands

Illustration of waves of heat from a radiating sun surrounding residential buildings, by Jericho Tang
Jericho Tang/File

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Humanity’s impact on the environment is undeniable. Urban Heat Islands, or UHIs, are often an underlooked yet well-documented example of the environmental alteration occurring in many cities.

In simple terms, concentrations of asphalt, cement and other surfaces absorb solar heat then radiate it back into the environment at a higher rate than that of natural landscapes. The pattern of who lives closer to heat sources is not one of poor versus rich, but rather, of minority versus majority. Studies have shown that low-income communities of color are most susceptible to the effects of UHIs. The lasting effects of redlining, which was banned in 1968, forced people of color into less desirable areas. These communities are characterized by fewer trees and more concrete and often exist closer to highways and factories, all of which increase heat.

Surface temperature and income maps in cities reinforce the trend’s existence. The lower the average income, the higher the average surface temperature. The effects of UHIs directly stem from past environmental justice issues. As the planet warms, the urban poor will continue to experience more extreme heat than the wealthy. NPR analyzed 97 of the most populous U.S. cities, crossing median household income data from the U.S. Census Bureau with thermal satellite images from NASA and the U.S. Geological Survey. They discovered in more than three-quarters of cities analyzed, there was a correlation between heat and lower-income communities.

According to the Environmental Protection Agency, or EPA, the annual air temperature of a city containing one million people can fluctuate from one to seven degrees Fahrenheit warmer than its surrounding rural areas. Buildings nowadays are quite effective at insulating, controlling inside temperature while simultaneously heating the outside. Structures in close proximity form UHIs. High consumers whose specific geographical locations are not yet majorly altered by climate change are most likely to lead excessive lifestyles. The financially secure can control their heat exposure with air conditioning, only further contributing to climate change. To support our skyrocketing population’s consumeristic habits, the ecosphere is stripped of its biodiversity as biomes are altered and harvested beyond repair. 

Heat records have become the norm on an annual basis. As sea levels rise and weather events intensify, rising temperatures exist as the most tangibly felt component of habitat loss. Indigenous populations continue to be displaced, losing their culture and native land. Therefore, they often suffer in the hottest areas with the worst air quality, magnified by poor living conditions. With the Supreme Court’s most recent rulings striking down the EPA’s ability to regulate emissions and limiting the land rights of Indigenous people, the facts above are more true than ever. Bringing light to causes of climate migration does an excellent job of explaining the dire situations climate migrants face.

City planners and architects must adapt and learn from the built environment, considering the effects of UHIs and how to best mitigate their effects in future expansion. The incorporation of green and cool roofs reduces solar absorption, providing both direct and ambient cooling effects. Green roofs also improve air quality by reducing the UHI effect and absorbing pollutants.

Studies like the Urban Heat Mapping Campaign accept applications multiple times per year. Receiving little government aid, they are in constant need of support. These efforts led by the National Integrated Heat Health Information System promote awareness backed with accurate evidence. As individuals, we can limit our waste heat caused by fossil-fueled tools and practice water-conscious habits. Planting native, drought-resistant vegetation, shade trees or any groundcover wherever possible will transform communities one step at a time.

Contact Alexander Brown at [email protected].