Study Reveals Extreme Heat Accelerates Molecular Aging in Humans

Extreme heat poses a significant threat to human health, with recent research indicating that it may accelerate biological aging at the molecular level. This alarming finding raises urgent public health concerns, particularly as climate change continues to intensify heatwaves worldwide.

In a study published in the journal *Science Advances* in March 2025, researchers led by Dr. Eunyoung Choi, a postdoctoral associate in Gerontology at the University of Southern California, analyzed blood samples from over 3,600 older adults across the United States. The study measured biological age using epigenetic clocks, which assess DNA methylation patterns that alter with age. These modifications serve as switches that can turn genes on or off, influencing aging and disease risk over time.

Dr. Choi noted, "Our findings suggest that long-term exposure to extreme heat may speed up biological aging, raising concerns about the long-term health risks posed by a warming climate."

The research revealed that older adults living in areas with frequent extreme heat days—defined as days when the heat index exceeds 90 degrees Fahrenheit (32.2 degrees Celsius)—experienced up to 14 months of additional biological aging compared to those in cooler environments. This association persisted even after controlling for various factors, including socioeconomic status and physical activity levels.

The results indicate that extreme heat may affect biological aging similarly to major lifestyle factors such as smoking and excessive alcohol consumption. According to Dr. Choi, "Extreme heat exposure may be silently accelerating aging, akin to other known environmental stressors."

The study’s findings underscore the urgent need for public health strategies to mitigate the impact of extreme heat, especially for vulnerable populations like older adults, who may struggle to regulate their body temperature effectively. This demographic is particularly at risk as many take medications that impair their heat tolerance, making even moderately hot days potentially hazardous.

Dr. Sherry L. Van Tine, a geriatrician at the Mayo Clinic, emphasized, "The link between extreme heat and accelerated aging is concerning. We must prioritize developing age-appropriate solutions that enable older adults to remain safely within their communities despite the rising temperatures."

Furthermore, the implications of these findings extend beyond individual health. As the global population ages and climate change progresses, the potential for increased healthcare costs and a greater burden on health systems becomes apparent. According to the World Health Organization (WHO), climate change is expected to cause 250,000 additional deaths per year between 2030 and 2050 due to heat-related health issues.

In response to these challenges, communities are urged to adapt by improving access to cooling resources, such as air conditioning and public cooling centers, and by implementing urban planning strategies that prioritize heat reduction.

Dr. Choi concluded, "Our research highlights the need for continued investigation into how environmental factors influence aging. As we confront a future marked by climate change, understanding these connections will be crucial for protecting public health."

As this study reveals, extreme heat is not merely an immediate hazard; it may represent a silent accelerator of aging with significant long-term public health consequences. With the ongoing rise in global temperatures, the urgency to address this issue is more critical than ever, necessitating collaborative efforts from policymakers, healthcare providers, and communities alike.