Urban Heat Islands
Harava Rahardjo ’25
Daphne Wong ’26
A city's area is deemed an urban heat island when the average temperatures are noticeably higher than surrounding suburban and rural areas. Large urban areas typically house significantly more energy sources than any other, as there are constant activity flows from people, especially with car use, industrial factories, trains, or electricity. Energy is continually burnt off in cities and is often released as “waste heat” (Urban Heat, n.d.). Compound this with the activity of thousands or even millions of urban dwellers: you get an overwhelming accumulation of heat. Large cities like New York City, Paris, Lagos, and Hong Kong have urban heat islands, and the infrastructure in those cities is insufficient to help dissipate that heat (Wilson et al., 2022).
Cities replace natural land with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat (United States Environmental Protection Agency, n.d.). Residential areas, office buildings, industrial infrastructure, and other aspects of human activity in urban areas are often built near each other and consist of materials designed for insulation, thereby trapping heat within and between the infrastructure that pervades urban areas. Due to increasing urbanization resulting in more densely populated living conditions, buildings are naturally constructed closer together and built upward, creating crowded areas of high-rise heat-trapping infrastructure. Heat cannot escape this and instead linger in the urban areas.
There is also evidence that specific areas and groups of people within cities are disproportionately more likely to be impacted by the effects of an urban heat island. According to one study by Nature Communications using surface urban heat island (SUHI) data, in the United States, the average person of color lives in an area with higher SUHI intensity than non-Hispanic whites in all but 6 of the 175 largest urbanized areas (Hsu et al., 2021). Socioeconomic factors also impact the distribution of urban heat island impact, as poorer neighborhoods are significantly more exposed to urban heat island effects than their wealthier counterparts (Chakraborty et al., 2019).
Local government officials and policymakers must make infrastructural efforts to lessen urban heat islands' adverse health, social, and environmental impacts. However, all inhabitants of urban areas can make an impact. Potential solutions include planting trees and other vegetation. This could also include building “green roofs,” which provide direct and ambient cooling effects, and advocating for continued investment in heat-reducing practices (United States Environmental Protection Agency, n.d.).
References
Chakraborty, T., Hsu, A., Manya, D., & Sheriff, G. (2019). Disproportionately higher exposure to urban heat in lower-income
neighborhoods: A multi-city perspective. Environmental Research Letters, 14(10), 105003. https://doi.org/10.1088/1748-9326/ab3b99
Hsu, A., Sheriff, G., Chakraborty, T., & Manya, D. (2021). Disproportionate exposure to urban heat island intensity across major US
cities. Nature Communications, 12(1). https://doi.org/10.1038/s41467-021-22799-5
United States Environmental Protection Agency. (n.d.). Reduce Urban Heat Island Effect. United States Government.
Urban Heat Island. (n.d.). National Geographic. https://education.nationalgeographic.org/resource/urban-heat-island/
Wilson, H., Sottman, S., Shoemaker, K., & Strong, A. (2022, April 7). The Urban Heat Island Effect Around the World.
https://storymaps.arcgis.com/stories/c7858f77646c4ca3b8c83d0f83d5c7b4
