Urban Heat Management and the Legacy of Redlining

How can planners address historical planning errors that continue to produce unjust urban conditions? With equity being prevalent in the popular lexicon, planners need to reckon with planning's past to make cities more equitable.

Equity Planning Addresses Urban Historical Injustices

In "Urban Heat Management and the Legacy of Redlining" in the Journal of the American Planning Association (Vol. 86, No. 4), Bev Wilson, AICP, uses the lens of equity planning to analyze how histories of disinvestment have caused uneven exposure to heat in cities. Wilson examined redlining practices, land surface temperature, and demographic data of current residents in Baltimore, Dallas, and Kansas City, Missouri. Wilson found that sections of these cities that were once targets of redlining now have higher mean land surface temperatures than other areas of these cities that were given more favorable ratings on redlining maps. In all three of these cities, poor and minority populations are overrepresented in these formerly redlined areas. This varied by city with the least difference in temperature between redlined districts found in Kansas City and the most in Baltimore, as shown in the figures below.

Figure 1: Heat in Kansas City mapped by Federal Home Owner's Loan Corporation class.

Figure 2: Heat in Baltimore by Federal Home Owner's Loan Corporation class.

Addressing Urban Heat Through Equity Planning

Surface heat temperatures in developed urban areas can be up to 27°F hotter during the day than in rural areas. This can present cities and their residents with the problem of urban heat island (UHI) effect in certain areas. The consequences of extreme heat are well-documented in public health and medical studies. Rising temperatures can overwhelm our bodies, resulting in heat exhaustion, dizziness, muscle cramping, and other ailments.

Mapping heat vulnerability has allowed planners to identify UHIs and target areas for intervention to manage rising temperatures. Some interventions include efforts like increasing the tree canopy in a heat-vulnerable area. However, Wilson argues that urban heat management through the lens of equity planning could allow planners to confront the role that historical policies have in creating and maintaining inequity today.

Equity planning "emphasizes centering social problems like poverty and segregation, recognizing planning practice as inherently political." Through this lens, identifying areas that are vulnerable to heat increases could also demonstrate connections to racial discrimination, lasting patterns of residential segregation, and access to green space. This would open planning to more opportunities to consider patterns of injustice inflicted upon marginalized groups.

The history of racist practices: environmental injustice, racial covenants, redlining, and other forms of disinvestment, continue to have lasting effects on communities across the country. Urban planners have played a role in these practices and in advocating for "federal programs that provided incentives for major roadway building construction projects" in low-income areas. These areas were often populated by minority populations. It is not a coincidence that the introduction of more heat-retaining materials, like asphalt, has resulted in heat increases.

A crucial implication of this research that Wilson highlights is the effects of climate change on heat management. In the coming years, climate change will continue to demand comprehensive responses to mitigate its effects. While heat management may not be the most threatening effect of climate change in every city, mitigating heat has to be addressed with other climate change mitigation efforts. The application of climate change mitigation strategies should not continue to fall into the pattern of unjust and inequitable practices that are abundant in the history of planning.

Planners must reckon with the negative intended and unintended consequences of planning and policy decisions that will threaten urban habitability. This research presents planners with the chance to consider practices of disinvestment and racism to holistically identify vulnerabilities that impact minority communities.

Top image: Residential Security Map of Baltimore (often called the Baltimore redlining map), published in 1937 by the Federal Home Owner's Loan Corporation. Courtesy Johns Hopkins Sheridan Libraries & University Museums.