Amidst a summer of blistering temperatures, a disturbing trend has emerged in the United States: heat-related deaths have more than doubled over the past two decades. According to new research published in the Journal of the American Medical Association (JAMA), the number of deaths attributed to extreme heat rose by 117 percent between 1999 and 2023. This alarming increase underscores the deadly impact of climate change and the urgent need for comprehensive public health measures.
Researchers from the University of Texas at San Antonio, Pennsylvania State University, and the Uniformed Services University of the Health Sciences analyzed data from the U.S. Centers for Disease Control and Prevention (CDC) spanning 25 years. They identified 21,518 deaths during this period where heat was either the underlying or a contributing cause of death. The number of fatalities fluctuated year to year, but the overall trend reveals a significant and troubling rise.
In 1999, there were 1,069 heat-related deaths recorded. This figure dipped to a low of 311 in 2004, but by 2023, the number had surged to 2,325—the highest annual total recorded in the study. Last year also marked the hottest year on record globally, a dubious milestone that scientists warn could be surpassed in 2024. The researchers found that the sharpest increases in heat-related mortality occurred after 2016, with deaths rising by 16.8% per year from 2016 to 2023.
Dr. Jeffrey Howard, an associate professor at the University of Texas at San Antonio and lead author of the study, noted that the rising temperatures are directly influencing the increase in deaths. “The current trajectory that we’re on, in terms of warming and the change in the climate, is starting to actually show up in increased deaths,” he told USA Today. “That’s something that we hadn’t had measured before.”
The increase in heat-related deaths is not evenly distributed across the country. The study found that Arizona, California, Nevada, and Texas had the highest number of fatalities. These states are known for their extreme summer temperatures, but the findings highlight the regional disparities in heat vulnerability. “This is not terribly surprising because we know that these are some of the hottest regions in the country, but it does reinforce that the risk varies regionally,” Howard explained.
Rising temperatures due to climate change are undoubtedly a significant factor in the surge of heat-related deaths. The study’s authors point to the increasing number of “hot days” and the growing frequency and intensity of heatwaves as key contributors. However, social and behavioral factors also play a crucial role in this public health crisis. Differences in access to air conditioning, the prevalence of outdoor work, and the number of un-housed individuals are all factors that exacerbate the risk of heat-related illnesses and fatalities.
The dangers of extreme heat are not confined to the United States. A recent study published in Nature Medicine estimated that 47,000 people died due to heat in Europe last year. The global nature of this crisis underscores the need for international cooperation and action to address the impacts of climate change on public health.
Despite the alarming rise in heat-related deaths, experts caution that the true toll of extreme heat may be even higher than reported. The way heat-related deaths are tracked can lead to underestimation. “People may present to the Emergency Department or the hospital with a heart attack, stroke, asthma attack, or kidney failure, and heat is often not recorded in medical records as the underlying cause,” Dr. Céline Gounder, a medical contributor for CBS News, explained. This misclassification can obscure the full extent of the impact that rising temperatures have on mortality rates.
As temperatures continue to climb each year, local and state governments are scrambling to implement life-saving measures. The JAMA authors recommend expanding access to cooling centers, increasing the availability of air conditioning in homes, and investing in hydration centers to help people cope with extreme heat. These measures are particularly critical in high-risk areas like the U.S. Southwest, where the combination of scorching temperatures and socioeconomic factors makes the population especially vulnerable.
The study also calls for improvements in the way heat-related deaths are recorded. Howard pointed out the variability in death certification procedures across U.S. counties, which could be mitigated with additional standardization. Properly counting these deaths is essential for understanding the full scope of the problem and for implementing effective public health strategies.
In addition to these public health measures, there is a growing movement to hold fossil fuel companies accountable for their role in the climate crisis. A legal memo published by the watchdog group Public Citizen in June argued that local or state prosecutors could bring criminal charges against oil and gas companies for deaths linked to extreme heat. “These victims deserve justice no less than the victims of street-level homicides,” said Aaron Regunberg, senior policy counsel for the group. “And this memo shows that prosecutors have a path to secure that justice, if they choose to pursue it.”
“The current trajectory that we’re on, in terms of warming and the change in the climate, is starting to actually show up in increased deaths,” Howard said.
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