by Daniel Brouse
July 25, 2025
Extreme heat doesn't just make you uncomfortable--it makes you age faster. Prolonged exposure to high temperatures accelerates biological aging by damaging cells and tissues, undermining human health at the molecular level.
"An accelerated biological age is the ‘canary in the coal mine' for future risk of earlier onset of diseases such as cancer, dementia, and diabetes, and early death," explained Jennifer Ailshire, professor of gerontology and sociology at the University of Southern California Leonard Davis School of Gerontology.
As climate change drives increasingly severe and longer-lasting heat waves, life expectancy is likely to decrease. This is not a distant projection but a direct, ongoing reality. Extreme heat disrupts sleep, increases dehydration, and places chronic stress on the cardiovascular and respiratory systems, worsening preexisting conditions and triggering new ones.
This is just one example of how climate change is reducing both the quantity and quality of human life. The impacts of extreme heat are not evenly distributed: older adults, children, outdoor workers, and low-income communities face disproportionate risks due to limited access to cooling, healthcare, and adaptive infrastructure.
Our DNA provides the blueprint for how our bodies function, and while the sequence of our DNA is set at birth, the expression of these genes--how that blueprint is carried out--can change in response to environmental factors.
Extreme heat can trigger epigenetic changes, chemical modifications that turn genes on or off like a light switch. These changes can activate high-risk genes associated with cancer, diabetes, cardiovascular disease, and neurological disorders, increasing susceptibility to these conditions later in life.
The USC study found that older adults exposed to extreme heat showed markers of accelerated biological aging. This cellular aging is a predictor of early disease onset and mortality, highlighting the hidden toll of rising temperatures.
As temperatures rise, reliance on air conditioning increases, leading to higher energy demand, which--if powered by fossil fuels--further accelerates climate change and increases heat exposure. This creates a vicious cycle of heat, emissions, and health decline.
At the same time, heat waves often coincide with higher levels of ground-level ozone and particulate pollution, compounding cellular damage and inflammation, and worsening cardiovascular and respiratory health.
Mitigating climate change is a public health imperative. Policies that rapidly transition energy systems away from fossil fuels, expand urban green spaces, and improve building designs to keep people cool without excessive energy use are critical.
At the individual level, strategies to reduce heat exposure, stay hydrated, and monitor health during heat waves can help, but systemic changes are necessary to address the accelerating threat of climate-driven aging and mortality.
Extreme heat is not just a discomfort or inconvenience; it is a biological stressor accelerating aging, reducing lifespans, and increasing the risk of chronic disease. As climate change continues to intensify heat waves, we can expect an increase in age-related health conditions occurring earlier in life, underscoring the urgency of climate action as a health intervention.
Climate Change and the Surging Threat of Pathogen Vectors Brouse (2025)
Climate-Driven Health Collapse: The Compounding Feedback Loops of Disease, Pollution, and Extreme Weather Brouse (2025)
How Extreme Heat Accelerates Aging and Cuts Life Expectancy Brouse (2025)
* Our climate model -- which incorporates complex social-ecological feedback loops within a dynamic, non-linear system -- projects that global temperatures could rise by up to 9°C (16.2°F) within this century. This far exceeds earlier estimates of a 4°C rise over the next thousand years, signaling a dramatic acceleration of warming.
We analyze how human activities (such as deforestation, fossil fuel use, and land development) interact with ecological processes (including carbon cycling, water availability, and biodiversity loss) in ways that amplify one another. These interactions do not follow simple cause-and-effect patterns; instead, they create cascading, interconnected impacts that can rapidly accelerate system-wide change, sometimes abruptly. Understanding these dynamics is essential for assessing risks and designing effective climate adaptation and mitigation strategies.