If this year feels hotter than the ones you remember, you're not imagining it.
Across the United States and around the world, extreme heat events are becoming more frequent, more intense and longer lasting. These rising temperatures are supercharging natural disasters such as hurricanes and wildfires. Scientists warn that the trend will continue as the climate warms.
At Duke University, researchers across medicine, engineering, environmental science and public policy are studying what this means for human health, ecosystems and communities. Their work spans everything from kidney disease in agricultural workers to urban heat maps and coral reef survival.
Together, this research paints a picture of a challenge that reaches far beyond uncomfortable weather.
"Government, companies and community organizations must start working together on developing the strategies, tools and partnerships needed to reduce heat exposure and enhance resilience," said Ashley Ward , director of the Heat Policy Innovation Hub at Duke's Nicholas Institute for Energy, Environment & Sustainability .
How Does Extreme Heat Affect the Human Body?
Heat illness is often associated with dehydration, exhaustion or heat stroke. In fact, it's the number one weather-related killer in the U.S.
But it's not necessarily the daytime highs that are the issue, says Ward : It's the still-elevated nighttime lows that can continue to tax the body in dangerous ways.
"Your body needs a reprieve," she told the AP . "[If] you don't get that overnight, we start the next day at a deficit."
Duke researchers are also studying how rising temperatures may contribute to a mysterious epidemic of kidney disease affecting agricultural communities around the world.
"What we're seeing is a rise in kidney disease in communities with no other major risk factors," said Nishad Jayasundara , an environmental health researcher at the Nicholas School of the Environment and the Duke Global Health Institute . "Perfectly healthy, able-bodied men who've worked in hot, dry conditions for years suddenly show up at the hospital with stage-four kidney failure."
The condition, known as chronic kidney disease of unknown cause, has devastated farming communities in Sri Lanka, India and Central America. In some regions of Nicaragua, researchers estimate one in three men has end-stage kidney disease.
Scientists say repeated heat stress may damage the kidneys over time.
"But what's happening with chronic recurrent heat exposure? We don't know very much," said Dr. Mary Helen Foster , a Duke University School of Medicine nephrologist studying the condition. "We study acute heat stroke, but we've barely scratched the surface of what long-term, repeated heat exposure does to the body."
Some of this research involves partnerships with federal agencies, including the National Institute of Environmental Health Sciences, highlighting how federal investment supports investigations into emerging health threats.
Researchers are also examining whether similar risks could affect agricultural workers in North Carolina, who often work long hours harvesting crops in intense summer heat.
Who Is Most Vulnerable to Extreme Heat?
Heat does not affect everyone equally.
Outdoor workers, older adults, people with chronic illnesses and communities with limited resources often face the highest risks.
At Duke, Elizabeth Rojo , a Ph.D. student in population health sciences, is studying how extreme heat affects farm workers in North Carolina .
"Farm workers are the backbone of our agricultural system," Rojo said. "Yet they are at a higher risk of poor health outcomes due to climate change because of the nature of their work and poor worker protections. They are more vulnerable to heat-related illnesses and increased chronic conditions."
Working with the North Carolina Farm Worker Health Program, Rojo conducts interviews and field visits during the heat season to better understand the experiences of workers in the field.
"I consider myself an advocate of the community," she said. "I want the community to be partners - not just participants - every step of the way."
Young athletes can also face serious risks when practicing in extreme heat.
Jordan Clark, a consulting scientist with the Heat Policy Innovation Hub and the Duke Global Health Institute, has worked with athletic associations to promote safer heat protocols .
"As heat waves become more frequent and intense, it's crucial that high school athletic associations implement comprehensive heat safety protocols," Clark said. "Proper environmental monitoring, activity modifications and venue-specific plans can significantly reduce the risk of heat-related illnesses among student-athletes."
Clark recommends gradual acclimatization to heat conditions. "This means starting athletes at a much-reduced level of exertion - around 20% of what would be their maximum effort at the end of last season - and slowly ramping up over about two weeks," Clark said.
What Are the Economic Impacts of Heat in the U.S.?
In addition to heat's effects on human health and ecosystems, the warming climate also threatens U.S. economic growth.
Bridging Divides , a new project from the Heat Policy Innovation Hub, provides data and insights on heat's hidden costs across multiple sectors: health, energy, agriculture, labor, transportation, infrastructure and housing. Using interactive maps, this project examines topics as wide ranging as crop insurance losses , labor productivity in local economies and impacts to bridges .
Data in the maps is presented at the level of congressional districts so people can see exactly how their area is affected. More stories with these interactive maps will be released over the next year.
These tools can help policymakers, businesses and communities understand not only the impacts of heat, but also how solutions could benefit multiple economic sectors.
"If we get serious about heat, we won't just weather the summer - we will protect workers, safeguard infrastructure and strengthen the systems that communities rely upon every day, building a more resilient economy for everyone," Ward wrote in a New York Times op-ed .
Why Might Your Neighborhood Be Hotter Than the Weather App Says?
Temperature readings from weather apps may not always tell the full story.
Research from Duke engineers shows that the hottest neighborhoods in cities are often underrepresented in temperature data, which can lead to underestimating how dangerous heat conditions really are .
Many weather platforms rely on personal weather stations installed by volunteers. But those stations tend to be located in wealthier neighborhoods.
"The poorest areas of a city also tend to have the fewest number of weather stations to pull data from," said Zach Calhoun, a civil and environmental engineering Ph.D. student at the Pratt School of Engineering .
Working with David Carlson , assistant professor of civil and environmental engineering, the team developed statistical methods to correct for missing data and improve estimates of urban heat.
"Our work highlights the need for additional weather stations so we're aware of just how much hotter the summer is for the poorest members of our community," Carlson said.
Better data could help cities design policies that reduce heat exposure, from planting trees to establishing cooling centers.
The same team is working with local households to better understand how these overlooked heat islands combine with local pollution levels to affect the health of community members.
Can Rising Temperatures Change the Diseases We Face?
Heat doesn't only affect people directly. It can also influence microbes and pathogens that can infect humans.
At Duke, assistant professor Asiya Gusa and microbiology colleagues are exploring how warming temperatures may allow environmental fungi to adapt to human body temperatures and cause infections.
"We are especially focused on how fungi adapt to high temperatures and how changes in the environment contribute to the spread and exposure of people to disease-causing fungi," Gusa said.
Researchers are also investigating how heat may affect the body's microbial ecosystem.
A Climate and Health Big Idea Grant at Duke is supporting work by molecular genetics and microbiology professor John Rawls , who is studying how heat exposure alters the human microbiome and how those changes influence disease risk.
The interdisciplinary program provides funding to accelerate research on climate-related health threats. Many have a connection to heat the researchers want to tease out, including:
- Rural Carolinas Observatory for Heat Early Warning and Health Resilience, from associate professor João Ricardo Nickenig Vissoci
- Trauma Recovery in a Changing Climate: Impacts of Extreme Heat and Air Pollution on Biological Risk for PTSD, from assistant professor Kate Webb
- Mapping Melanoma Vulnerability in North Carolina: The Link Between UV Exposure, Temperature, and Geographic Risk, from medical student Sakshi Chopra
- Extreme Heat Events and End-Stage Renal Disease (EHE-ESRD), from Ph.D. student Rebecca Fillipo
How Are Health Professionals Preparing for a Hotter World?
As extreme heat becomes more common, health systems are beginning to adapt.
At the Duke University School of Nursing , Valerie Sabol leads planetary health initiatives aimed at helping nurses recognize and respond to climate-related health risks .
"Nurses are on the front lines - we're often the first ones to see emerging health trends, whether it's an increase in heat-related illnesses or the effects of poor air quality," Sabol said.
In her clinical work, nurses have begun screening patients for heat-related risks before surgery and reviewing medications that may affect how well patients tolerate extreme temperatures.
"When the body's cooling becomes insufficient, the heart must work harder, and dehydration develops more quickly, putting strain on those living with heart disease, high blood pressure, kidney disease, diabetes and respiratory illnesses," Sabol explained. "Extreme heat often coincides with poor air quality, which can worsen asthma, COPD [Chronic Obstructive Pulmonary Disease] and heart disease. This means during heat waves, it's especially important to monitor local air quality reports and limit outdoor activity if needed."
Anticipating these risks, she said, can help prevent complications before they occur.
What Can Extreme Heat Teach Us About Protecting Ecosystems?
The impacts of rising temperatures extend far beyond human health.
At the Duke University Marine Laboratory , researchers are studying how coral reefs respond to heat stress. They found that small reef-dwelling crabs may help certain corals survive heat waves and injury .
"Foundation species like corals create the base of an ecosystem," said Julianna Renzi, who conducted the research as a graduate student at Duke. "Learning how these species respond to stress can help us design better strategies to conserve them."
The findings show how ecological partnerships can sometimes buffer species from environmental stress.
"This work challenges a paradigm about corals," said Brian Silliman , a marine ecologist at the Nicholas School of the Environment. "An intricate biological partnership greatly increases the ability of corals to resist heat stress."
Keeping corals healthy is critically important as they support communities of both marine life and people. The National Oceanic and Atmospheric Administration estimates that a quarter of all marine life relies on reefs, which only take up 1% of the world's oceans, and the economic value of reefs to U.S. fisheries is more than $100 million.
What Will It Take to Prepare for a Hotter Future?
Across these projects, Duke researchers are studying extreme heat from multiple angles - from human health and infrastructure to ecosystems and infectious disease.
Their work underscores a growing reality: Heat is no longer just a seasonal inconvenience. It's becoming a defining challenge for public health, cities, agriculture and the environment.
Through interdisciplinary research - often supported by philanthropic and federal investment - scientists at Duke are working to understand heat risks and help communities prepare for the hotter decades ahead.
Learn more about how federally funded Duke Research Saves Lives .
