Introduction
Climate change has increased concern over warm season temperatures due to the health effects of extreme temperature exposures (1). In the United States, a small body of literature documents disparities in summertime temperatures experienced by ethnoracially minoritized subgroups (2, 3). This is a concern for several reasons. Minoritized subgroups have increased temperature vulnerability (4, 5), which may be due to higher levels of comorbidities (6–8). Further, air temperature estimates may systematically underestimate true exposures for vulnerable populations (9, 10), so the effects of these exposures also may be underestimated. In addition, minoritized populations experience higher energy burden and energy insecurity (11, 12). Given that air conditioning is the dominant individual-level adaptive strategy to heat in the U.S., minoritized populations may have reduced adaptive capacity to climate change (13, 14). Thus extreme temperature exposures represent a form of underestimated structural racism in climate impacts.
Social disadvantage and temperature exposure are related. Spatial temperature profiles are correlated with socioeconomic status, and land use/cover associated with the urban heat island effect is more prevalent in poor communities and communities of color (3, 15). More recently, Hoffman et al. identified an association between the Home Owners’ Loan Corporation historical housing practices, often referred to as “redlining”, and higher summertime land surface temperatures within cities (2). This work is bolstered by evidence that places benefiting from these lending practices now have attributes associated with lower summertime temperatures, such as increased vegetation and less impervious surfaces (16, 17). However, populations and developed land area have grown substantially since the 1940s. Thus while previous studies are integral to understand the formation of environmental inequities, present-day interventions would benefit from analyses associating current measures of segregation with air temperature. Further, many previous studies have used land surface temperatures, but near-surface air temperatures measured at ground-based monitors are more relevant for human thermoregulatory capacity and energy policy.
In the U.S., there is growing recognition of energy burden and energy insecurity (18, 19), yet few policies that explicitly protect disadvantaged groups that experience these hardships (20). The Low-Income Home Energy Assistance Program (LIHEAP) is one such protection program, but it largely distributes funding based on cold season energy demand and provides less support for the warm season (21). Indirect measures of energy demand are used to calculate LIHEAP funding allocations, specifically heating and cooling degree days. Although allocations assume that everyone in a state or region is exposed to roughly equal temperatures, residential segregation and temperature both vary over fine spatial scales. Thus air temperature disparities may mean that minoritized groups are exposed to systematically higher summer temperatures. Here we used a fine spatial resolution air temperature product to assess the potential relationship between area-level ethnoracial composition and warm season air temperatures. We asked:Do minoritized groups experience hotter summers than the area average, and do non-Hispanic white people experience cooler summers? We then tested whether present-day measures of segregation are associated with summertime temperatures, exploring a likely pathway between exposure and temperature vulnerability.