Extreme Heat in Washington, DC
Impact of historical discriminatory housing policies on modern-day vulnerability to heat
The nation's capital experiences the urban heat island effect, leaving city dwellers at risk to extreme heat (Smith, 2017). Despite boasting an abundance of green space, racist housing policies have exacerbated inequalities and disproportionately exposed marginalized communities to extreme heat.
In the early 1930’s, the Federal Housing Administration established a racial criterion for the distribution of loans. Thereafter, the Home Owners' Loan Corporation used these criterion to assign rankings to areas for development. Black communities received a low ranking and were deemed risky for investment while white areas benefited from desirable valuation (Michney & Winling, 2020).
Assessments conducted by the Department of Energy and Environment such as the Vulnerability and Assessment and Climate Ready D.C. explore heat in the nation's capital. However, these evaluations lack a discussion on the role race plays in inequitably exposing communities of color, particularly Black neighborhoods, to heat.
Methods
Our team used two main frameworks for our analysis: the natural hazards approach model and the pressure release model of political ecology.
Land Surface Temperature (LST) data was the primary environmental factor that we examined.
Social demographics data, including race, age (younger than 14 or older than 65), and poverty data, was compared to historically redlined zones to show the spatial relationships that still exist in the present day.
Exposure
Extreme heat is an issue relevant to D.C. As average temperatures rise, physical infrastructure creates urban heat islands that drive temperature differences across the city. In fact, some areas have an ambient temperature that is 17 degrees Fahrenheit cooler than other sections of the city, which can reach temperatures of 102 (NOAA, 2018). High temperatures can cause heat exhaustion, stroke, and death (Luber & McGeehin, 2008). Hence, access to recreational or cooling centers are critical for residents to escape heat.
Comparing LST (Landsat derived) and impervious surfaces
An ANOVA test was performed comparing the average temperature by census tract to the two highest ranked and two lowest ranked historically redlined zones. Both highest ranked zones (A and B) were significantly different (p<0.05) than the two lowest ranked zones (G and H). Specifically, the analysis showed that the areas of the city that were once classified as H are now on average 5.6 degrees (F) hotter than areas that were classified as A.
Sensitivity
An individual’s sensitivity to extreme heat events is impacted by socioeconomic factors. More specifically, the American Planning Association identifies elderly people, racial minorities, and low-income groups as most at risk (Wilson, 2020). For this study, census data was used to map sensitivity based on age, race, and poverty in D.C. with specific consideration for redlined neighborhoods. Based on data for poverty level and race, regions located within wards 7 and 8 may be more sensitive to extreme heat.
Relationship between zoning classifications (left) and percent of Black population (right).
Percent of population in poverty in last 12 months.
Percent of population either over 65 (left) or under 14 (right) by census tract.
Adaptive Capacity
This study uses social capital, telecommunication, and the built environment to investigate adaptive capacity. To begin, having strong social ties can support residents in finding resources, help, and safety when temperatures rise (Wolf et al., 2010). Next, wireless communication is key for quickly sharing updates and information (DOEE, 2016). Finally, minimizing impervious surfaces while maximizing canopy cover can help cool down hot spots in the city (Fancis, 2020).