Assessing a South Carolina City’s Urban Heat Areas and Street Canopy Equity

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According to the NOAA National Weather Service, heat is the number one cause of weather-related deaths. As heat extremes intensify and risks to human health and life increase, media outlets that include the New York Times and National Geographic have called out unequal access to tree canopy cover, spotlighting “green” disparities based on socioeconomic status, racial composition, or both. In addition to health impacts, living in a hotter part of town results in higher electrical and cooling costs. In response, the City of Charleston undertook a subdivision-level analysis of urban heat areas and tree canopy cover to identify inequities in tree canopy distribution.


NOAA’s high-resolution C-CAP land cover data, when combined with local demographic data, gave city officials information on areas that were high in impervious surfaces and low on tree canopy cover. NOAA’s Heat Watch campaign yielded a separate data set on cross-city temperature variation on a hot summer day. These data were collected by volunteers driving or biking along prescribed routes with temperature sensors mounted to their vehicles. The data were used to identify public housing properties experiencing high heat relative to the rest of the city. Morning, afternoon, and evening temperatures averaged within public housing property polygons were plotted against tree canopy coverage to identify properties that might benefit from a heat mitigation measure.


A subset of 16 public housing properties with more than 40 units were selected for research in order to maximize the public benefit. The results were reported via an ESRI StoryMap and accompanying "Tree Canopy Tools" web application. These findings were used to secure NOAA grant funding for a heat pilot study in this residential community to better understand how heat is experienced on a microscale. (2023)

Aerial view of Charleston County street tree canopy areas in South Carolina.
Identifying tree canopy and high-heat areas. This map shows several communities in the Charleston County area and their relative amounts of street tree canopy. Communities identified in red are those with less than 20%. Credit: City of Charleston