As global temperatures escalate and heatwaves become increasingly frequent and severe, the human toll of extreme heat is reaching alarming proportions. Recent summers across Europe in 2022 and 2023 saw more than 100,000 deaths attributable to heatwaves alone, underscoring the urgent need to rethink our approach to managing heat stress. Traditional strategies centered on cooling the environment — primarily through reducing air temperature — are proving insufficient and often unsustainable. Leading experts from the University of Sydney advocate for a transformative paradigm shift: prioritizing the cooling of human bodies over solely focusing on ambient air temperature.
The human body’s response to heat is a complex interplay of environmental and physiological factors. When exposed to excessive heat, the body struggles to dissipate heat efficiently, leading to dangerous conditions such as heat stroke, exacerbation of cardiovascular and respiratory diseases, heart attacks, and even kidney failure. Heat stress does not merely hinge on the air temperature; radiation, humidity, and wind speed critically influence the body’s thermal load. Professor Ollie Jay and Dr. Federico Tartarini emphasize that a comprehensive understanding of these factors, combined with the physiological variability among individuals, is paramount to devising effective heat mitigation strategies.
Indeed, physiological differences—such as age, pre-existing health conditions, and medication—significantly dictate how the body regulates heat. Individuals with cardiovascular or renal impairments are disproportionately vulnerable to extreme heat. Despite this knowledge, existing public health policies often treat populations homogenously, failing to account for these physiological nuances. Professor Jay and Dr. Tartarini argue for a physiology-first model that integrates individual susceptibility to offer precise predictions about heat strain, enabling timely and targeted interventions.
This innovative approach is exemplified by the HeatWatch tool, a pioneering digital platform developed to personalize heat risk assessment. Users input personal data including age, health conditions, medication use, and access to cooling resources such as air conditioning. HeatWatch then generates a seven-day forecast tailored to their unique profile, offering evidence-based advice on mitigating heat-related health risks. By accounting for both environmental stressors and individual physiology, HeatWatch represents a significant advance in dynamic heat-health risk management.
Importantly, this tool is not merely theoretical. It has undergone pilot programs with various Sydney communities, including culturally and linguistically diverse and Indigenous groups, aiming to ensure inclusivity and practical applicability. The developers envision scaling this personalized physiology-based framework globally, especially targeting heat-vulnerable hotspots like Delhi, India, where heat stress incidents are rapidly increasing due to climate change.
A physiology-centric approach reframes the problem of heat resilience. Contrary to popular belief, cooling a person is not synonymous with cooling the surrounding air. Air conditioning, while effective, is resource-intensive, costly, and unavailable to many vulnerable populations worldwide. Moreover, environmental cooling measures like ground shading, designed to reduce ambient air temperature, do not necessarily translate to effective body cooling because human exposure to heat is influenced by complex factors beyond mere air temperature, such as radiation and airflow.
Professor Jay highlights that alternative strategies can effectively reduce bodily heat without incurring excessive carbon footprints. Increasing air movement using fans enhances evaporative cooling on the skin, while direct application of water can immediately dissipate heat. Furthermore, targeted shading that protects the human body from solar radiation, rather than simply shading the ground, provides more efficacious relief. Behavioral adaptation plays a significant role too; modulating physical activity to avoid peak daytime heat and optimizing work efficiency can reduce internal heat production, thus alleviating heat strain.
These insights underscore the multidimensional nature of heat stress and the importance of integrating physiology with environmental science to address it holistically. Such an approach balances technological innovation, public health imperatives, and sustainability. HeatWatch’s forward-looking, individually tailored forecasts aim to empower individuals and policymakers alike, creating adaptable response strategies that are both practical and equitable.
Global climate projections suggest that if the planet warms by 2 degrees Celsius from pre-industrial levels, heat-related mortality could surge nearly fourfold by 2050. This harrowing prediction compels urgent, innovative responses that transcend traditional interventions. The University of Sydney research underscores that managing heat stress requires nuanced appreciation of human thermoregulation and the socio-environmental contexts in which people live and work.
Ultimately, adopting a physiology-first framework heralds a new era in heatwave management, emphasizing precision, inclusivity, and sustainability. As climate change accelerates, such strategies will be indispensable in safeguarding public health. The integration of sophisticated physiological models with real-time environmental data for personalized risk assessment signals a transformative shift that could save countless lives worldwide during heatwaves.
Heatwaves are no longer just meteorological events—they are complex physiological challenges that demand equally sophisticated, human-centric solutions. Through innovations like HeatWatch and a foundational reimagining of heat adaptation strategies, science is charting a path towards effective, equitable, and sustainable heat resilience on a global scale.
Subject of Research: People
Article Title: To save lives in heatwaves, focus on how human bodies work
News Publication Date: 4-Aug-2025
Web References:
- Heat-related deaths projections: https://doi.org/10.1016/S0140-6736(23)01859-7
- Nature journal: https://www.nature.com/
- Professor Ollie Jay: https://www.sydney.edu.au/medicine-health/about/our-people/academic-staff/ollie.jay.html
- Dr Federico Tartarini: https://www.sydney.edu.au/medicine-health/about/our-people/academic-staff/federico-tartarini.html
- Heat and Health Research Centre: https://www.sydney.edu.au/medicine-health/our-research/research-centres/heat-and-health-research-centre.html
- HeatWatch: https://heatwatch.sydney.edu.au/
References: See above DOI and institutional links
Keywords: Environmental health, Physiology, Homeostasis, Body temperature regulation, Environmental stresses, Stressors, Europe, Australia, Environmental impact assessments, Climate policy, Environmental issues, Climate change, Climate zones, Global temperature
