By mid-century, the U.S. will be a much hotter place. Heatwaves will last longer, summer temperatures will soar, and the number of dangerously hot days will rise sharply\u2014especially in the US South. But not everyone will feel the heat in the same way.<\/span><\/p>\n \u201cAs the planet heats up, those least able to cope will suffer the most,\u201d says lead author <\/span>Zachary Popp<\/span><\/a>, research data analyst at Center for Climate and Health, School of Public Health<\/a> (SPH) at Boston University. \u201cWith public health resources already declining, it’s critical to address the health risks of extreme heat now to reduce the growing toll of extreme heat.\u201d<\/span><\/p>\n The study applied statistical and geospatial methods to pinpoint specific areas where future heat exposure will be both most intense and most dangerous due to the residents’ limited ability to respond. With this approach, the researchers aim to go beyond broad generalizations and ultimately empower local governments to prioritize resources where they’re needed most. Study co-authors include <\/span>Ian Sue Wing<\/span><\/a>, CAS professor of earth & environment; Kevin J. Lane,\u00a0<\/a> SPH professor of environmental health; and Gregory A. Wellenius<\/a>,\u00a0 SPH professor of environmental health and director of the Center for Climate and Health.<\/span><\/p>\n A New Way of Seeing Risk<\/b><\/p>\n In other related research, information is often studied in isolation. Climate scientists often project future heat extremes, while demographers track population change, and public health researchers map social inequities. The novel approach in this study brings together these three layers of data, delivering insights in a comprehensive and spatially precise way.\u00a0<\/span><\/p>\n \u201cOur multidisciplinary approach applies data-driven methods to help shift the question from \u2018How hot will it get?\u2019 to \u2018Which communities will be hardest hit\u2014and how can we help these communities reduce these risks?\u2019\u201d says Wellenius. \u201cThis makes the science timely, directly useful, and actionable.\u201d\u00a0<\/span><\/p>\n Projecting the Heat Burden<\/b><\/p>\n The study assessed the health-hazardous heat through multiple metrics: extreme hot days when the heat index exceeded 104 degrees, chronic heat through estimated air conditioning use, and acute heat through the 95th percentile high temperature (the temperature on the 20th hottest day of the year). To analyze rising temperatures, population changes, and social vulnerability collectively, the researchers examined 30+ global climate models and paired them with population projections. The study compared changes in heat and population to demographic and economic characteristics using the CDC <\/span>Social Vulnerability Index<\/span><\/a>. This index uses U.S. Census data to estimate how vulnerable each community is to disaster based on 15 social factors, including poverty, lack of vehicle access, and crowded housing.\u00a0<\/span><\/p>\n The study found that while the South and West – already hot- will see large absolute increases in heat, New England regions could see the largest relative increases, going from just a few hot days a year to many more. This geographical distinction is crucial for planning purposes. Southern states are generally better equipped for heat, with infrastructure designed for hot weather. In contrast, northeastern regions often lack adequate cooling resources, leaving residents particularly vulnerable to extreme heat.\u00a0\u00a0<\/span><\/p>\n A key takeaway from the study is that population growth in already hot regions could make extreme heat even more dangerous. Areas in the Southeast and Southwest face rising heat indexes and often have vulnerable populations without access to air conditioning to cope with extreme heat. Cities experiencing rapid urbanization and migration trends may struggle to adapt, especially if local infrastructure is not equipped to handle prolonged extreme heat events. \u201cCities are especially of interest because of urban heat island effects \u2013 less tree cover, more buildings and dark pavement means higher temperatures and more health risks,\u201d says Popp.<\/span><\/p>\n![\"Zachary](\"\/hic\/files\/2025\/05\/heat-divide-mapping-americas-map-95-percentile-636x406.png\")
A <\/span>BU-led study published in <\/span>Environmental Research: Health<\/span><\/i><\/a> reveals that the communities least equipped to handle rising temperatures will face the greatest increases in extreme heat exposure. And that\u2019s not just because of climate change\u2014it\u2019s also because of where people live, how fast populations are growing, and their social vulnerability as measured by poverty levels, housing quality, age, race, and other factors. Think of elderly residents in poorly insulated homes, low-income families who can\u2019t afford air conditioning, or urban neighborhoods with little shade and few cooling centers. These are the communities on the frontlines where heat will hit hardest.<\/span><\/p>\n![\"\"](\"\/hic\/files\/2025\/05\/zachary-popp.jpeg\")
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