How Redlining Drives Extreme Urban Heat Inequality

This section examines extreme heat as the leading weather-related cause of death in the US, yet receiving less public attention than hurricanes. Individual susceptibility varies dramatically based on age, health, and medication. The 1995 Chicago heat wave killed 800 people, with mortality concentrated in segregated, disinvested neighborhoods of color. Surface temperatures vary dramatically: shaded areas reach ~87°F while asphalt reaches ~170°F. Historical urban planning—including redlining and racial covenants—created lasting segregation patterns that persist today, making formerly redlined neighborhoods consistently warmer and more vulnerable to climate impacts.

The health risks from prolonged heat are cumulative and they are not evenly distributed. Elderly adults, especially those living alone without air conditioning in older housing stock with poor insulation, face dramatically higher risk than the general population numbers suggest. People with cardiovascular disease, chronic kidney disease, respiratory conditions, and diabetes are all in elevated risk categories for heat related hospitalization and death. And there are real equity dimensions here. Lower income communities, communities of color, and urban communities with less green space and more hard surface coverage face higher ambient temperatures and have less access to air conditioning or to the discretionary time needed to seek cooling during peak afternoon heat. Heat waves kill more Americans on average in any given year than tornadoes, hurricanes, floods, or lightning combined. And heat related illness and death is systematically undercounted in official mortality data because many heat related deaths are attributed to the underlying cardiovascular or renal condition that the heat exacerbated rather than to the heat itself. The real toll of summers like this one is almost certainly higher than what you will see in official preliminary counts. This heat wave is not just a record on a thermometer. It is a public health event of significant scale arriving in the context of a pattern that is going to keep producing similar events for at least several more weeks.

Heat waves increase population mortality rates by 10-15% during the event, with effects persisting for up to 7 days after the event ends. Older adults are more vulnerable due to physiological changes: the hypothalamus becomes less effective at temperature regulation, and sweating mechanisms become less efficient. Certain medications, including antidepressants and diuretics, can increase heat vulnerability. Research from Montreal's 2018 heat wave revealed significant geographic inequities, with residents of certain neighborhoods facing twice the mortality risk from heat exposure.

Urban heat inequality is driven by three interconnected factors: (1) Exposure - wealthier neighborhoods have more trees and parks that cool areas by up to 5°C, while poorer areas lack these natural air conditioners due to discriminatory policies like redlining; (2) Vulnerability - low-income residents face higher rates of health conditions (diabetes, heart disease, respiratory problems) that make heat more dangerous, compounded by aging populations in many regions; (3) Adaptive capacity - economic necessity often traps low-income workers in outdoor or poorly ventilated jobs without air conditioning. Solutions include green infrastructure investments (like Medellin's green corridors reducing temperatures by 2°C) and social programs (such as NYC's Be a Buddy program with 11,000+ heatwave check-ins).

Extreme heat is the leading weather-related killer in the United States, causing more deaths annually than hurricanes. Heat-related deaths are significantly underreported because deaths occurring during heat waves are typically recorded as heart attacks or other underlying causes rather than heat-related. States like Arizona have developed better systems for identifying heat-related mortality. Extreme heat creates climate justice concerns because vulnerable populations—those who cannot afford air conditioning, outdoor workers, and elderly residents—bear disproportionate burdens while those with resources can retreat to climate-controlled environments. Social cohesion plays a critical role, as isolated individuals without community connections face significantly higher risks during heat waves.

The cartographic application provides interactive map tools including zoom, pan, and home functions, plus address search capabilities. Three geographic information layers are available: satellite temperature data from Landsat 7/8, soil impermeabilization from aerial infrared photos, and equipment data from INSEE. Users can control layer visibility through the 'couche' tab, view legends, and select base maps (dark for highlighting data, orthophoto, or OpenStreetMap). This infrastructure enables systematic urban climate analysis across the 126 commune territory.

This video presents research on investigating urban heat island impact for the City of Chattanooga, TN using Geographic Information Systems (GIS) and Remote Sensing technologies, while also examining how Chattanooga has grown significantly over three decades.

Geographic Information Systems (GIS) technology displays information as visual maps and is essential for fire department operations. Departments use GIS for station optimization planning, analyzing historical data from records management systems, medical reports, and CAD information to determine optimal resource placement. GIS helps maximize the effectiveness of existing resources, identify performance improvements, and measure departmental performance for accreditation purposes. Thermal imaging technology detects heat signatures invisible to the human eye, allowing firefighters to see through smoke as if it weren't there. This enables rapid assessment of whether people are present in rooms during fires by detecting body heat and identifying fire locations within structures by seeing heat patterns on exterior walls. The technology also has HazMat applications for detecting hazardous material spills and assessing chemical tank contents.

Geographic Information Systems (GIS) capture, store, manipulate, analyze, and present spatial data for municipalities. GIS provides interactive mapping tools for staff to monitor infrastructure and development, and for residents to check zoning data and permits. Municipalities partner with county assessor's offices for GIS services, particularly before and after incorporation. The technology supports field inspections, parcel viewers, and integration with operational platforms. Service-based agreements provide cost savings compared to maintaining dedicated GIS staff.

This video demonstrates how to use Quantum GIS software to analyze and classify climate data for a specific municipality. The process involves downloading and installing QGIS, importing shapefile data for Brazilian municipalities and climate zones, creating a new shapefile for the target municipality, using attribute expressions to select the specific municipality, clipping climate data to the municipality boundaries, and categorizing the climate data to identify climate zones, temperature distribution, and humidity patterns. The example uses Caldas, Brazil, which is classified as Tropical Brazil Central climate with mesotermic warm temperatures (10-15°C) and varying humidity distribution (3-4 months dry or 1-2 months dry).

The Justice40 Initiative is a federal policy framework ensuring that benefits from climate, energy, clean transportation, and other federal investments reach disadvantaged communities that have historically been underinvested in and overburdened by pollution. This initiative represents a commitment to environmental justice, directing at least 40% of certain federal investments toward communities that have borne disproportionate environmental burdens while receiving insufficient public investment.

Justice 40 was an unprecedented executive order commitment by President Biden to direct 40% of the benefits from all federal climate and clean energy spending toward disadvantaged communities. Implementation required identifying disadvantaged communities using 36 data sets covering environmental hazards, climate vulnerability, and other burden indicators. Approximately 20% of census tracts were identified as disadvantaged by taking the 20th percentile of the most disadvantaged in each state. The initiative represented an all-of-government approach to ensuring that climate investments addressed historical inequities rather than perpetuating them.

President Biden's Executive Order 14008 established the Justice40 Initiative mandating that 40% of federal climate and clean energy investments go to disadvantaged communities—those experiencing climate impacts first and worst who cannot afford clean technology. This whole-of-government approach involves multiple federal offices including the Council on Environmental Quality, Office of Management and Budget, and White House Climate Policy Office, with external guidance from the White House Environmental Justice Advisory Council. After extensive development beginning during the presidential campaign, a 2022 map identified disadvantaged communities representing approximately 28% of the U.S. population. The Department of Energy established eight Justice40 policy priorities including addressing energy burden, achieving clean energy adoption parity, providing low-cost capital, ensuring diverse contracting, creating job training, focusing on resilience, and promoting energy democracy through procedural justice.

The Justice40 Initiative is a federal policy framework requiring that at least 40% of benefits from clean energy, sustainable housing, workforce development, pollution remediation, and clean water infrastructure investments flow to disadvantaged communities; however, this initiative is not a guaranteed funding pool but rather a goal that requires active community organizing, coalition-building, and engagement with local and state officials to ensure equitable distribution of federal climate and infrastructure investments.

Climate policy must address both mitigation (emission reduction) and adaptation, not just one or the other. Early in the administration, adaptation was not prioritized, but it is now recognized as essential. The Justice 40 Initiative commits to directing 40% of the overall benefits of investments to disadvantaged communities. This includes efforts to make communities more prepared for extreme heat, more resilient food systems, and more climate-ready infrastructure.