When heat becomes a health emergency
A warning sent before a dangerous heatwave can keep an older person out of hospital, protect an outdoor worker and ease pressure on an emergency department. At Adelaide University, researchers are turning evidence about climate change into practical systems that help governments, health services and communities protect people from one of this century’s defining public health threats.
Climate change is often described through rising sea levels, heatwaves and biodiversity loss. Its health toll is less visible, but it is increasingly recorded in deaths, hospital admissions, infectious and chronic disease, workplace injury, mental ill-health and widening inequity. The environmental crisis is also a health crisis.
The World Health Organization describes climate change as "the single biggest health threat facing humanity" and estimates that, between 2030 and 2050, it will cause approximately 250,000 additional deaths each year from malnutrition, malaria, diarrhoeal disease and heat stress alone. ¹
Those impacts are already being felt around the world, with more frequent and severe weather events bringing significant health consequences. In June 2026, a record-breaking heatwave swept across large parts of Europe, prompting heat-health warnings from the World Meteorological Organization, national weather agencies, and public health authorities. France recorded its hottest day on record, temperatures exceeded 40°C in parts of Spain and several countries issued their highest-level heat alerts.
By July, the World Health Organization's Regional Office for Europe reported that mortality data from five countries showed nearly 10,000 more deaths than would normally be expected for that time of year during the northern summer heatwave. The figures highlighted the substantial health impacts associated with extreme heat and the growing pressure climate change is placing on health systems and vulnerable communities.
The Adelaide University story is not simply that researchers are documenting these risks. It is that their evidence is moving into warning systems, workplace guidance, community programs and international health policy.
"Climate change has made a substantial impact on our society,"
Professor Peng Bi’s work shows how climate evidence can become protection during extreme heat. Associate Professor Zohra Lassi’s work shows why that protection must reach women, children and communities already facing barriers to care.
For Professor Bi, a public health researcher whose work has focused on climate change and health, the connection between the two is clear.
"Climate change has made a substantial impact on our society," he says.
As temperatures rise, rainfall patterns shift and extreme weather events become more frequent, health consequences emerge in ways that are not always immediately visible. Changing environmental conditions can contribute to higher rates of mosquito-borne diseases, food-borne illnesses, cardiovascular and kidney disease, workplace injuries and mental health problems.
"Infectious diseases are one example," says Professor Bi. "We have vector-borne diseases such as Ross River virus, Barmah Forest virus and Japanese encephalitis. All of these are relevant to increases in temperature and changing rainfall patterns."
Australia's exposure to extreme heat, drought, bushfires and other climate-related hazards has provided researchers with valuable insights into how environmental change affects human health.
Professor Bi's work has examined the effects of extreme heat, changing patterns of infectious and chronic diseases and occupational health risks, particularly among outdoor workers, emergency responders and older Australians.
Heat is among the deadliest climate-related health risks, yet it is easily underestimated because its damage is dispersed across homes, workplaces, ambulances and hospital wards rather than concentrated in a single visible disaster.
"Heat is often called the silent killer," says Professor Bi.
For many South Australians, the devastating 2009 heatwave remains a defining memory. The event exposed vulnerabilities across the community, particularly among older residents living alone.
Following that heatwave, Professor Bi and colleagues worked with SA Health, State Emergency Services, Bureau of Meteorology and other partners to establish South Australia's Heat and Health Warning System (HHWS). Implemented in 2010, the system provides early warnings when weather conditions are likely to pose significant health risks.
A subsequent evaluation comparing Adelaide's 2009 and 2014 heatwaves found significant reductions in ambulance callouts and heat-related emergency presentations following implementation of the warning system. ² An economic evaluation later estimated that every dollar spent activating the system could return between $2 and $3.30 in avoided health and emergency-service costs.
In 2022, the warning system was adopted nationally through Australia's National Emergency Management Agency framework. For Professor Bi, the achievement illustrates the value of research translated into policy and practice, including the Work in Heat policy for Safe Work Australia, and WHO’s Heat, air pollution and solar ultraviolet radiation report.
That approach has shaped a series of community-focused interventions. One initiative involving older South Australians combined simple educational materials and targeted messaging during periods of extreme heat.
The 2017 results, published in the International Journal of Environmental Research and Public Health, were striking. Professor Bi reports a 63% reduction in self-reported heat stress among senior citizen participants who received the intervention compared with those who received routine information.
The research has also extended to migrant communities, with multilingual health resources and community-led education campaigns designed to ensure critical health information reaches populations that may otherwise be overlooked because climate change does not affect everyone equally.
For Associate Professor Zohra Lassi, an epidemiologist whose research focuses on reproductive, maternal, newborn, child and adolescent health, the climate crisis is also an equity crisis.
"The same communities already facing the weakest healthcare access are the ones facing the sharpest climate risks," she says. "It's not two problems sitting side by side; it's one problem compounding another."
Her work examines how environmental pressures influence nutrition, maternal health, adolescent wellbeing and healthcare access, particularly in disadvantaged and low-resource settings.
"We started mapping the evidence on climate change and reproductive, maternal, newborn, child and adolescent health a few years ago, before it was as prominent an issue as it is now," she says.
For Associate Professor Lassi, one of the clearest messages from the evidence is that climate change can shape health outcomes before a child is even born. Extreme heat has emerged as a significant concern in maternal health research, while reviews of studies involving young children identified preterm birth, low birth weight and malnutrition among the most frequently reported outcomes associated with climate-related exposures. Research examining adolescents has highlighted growing concern about mental health impacts, while many physiological and psychosocial effects remain insufficiently understood. These findings were drawn from reviews of 133 studies on maternal health and 196 studies involving children under five.
She believes universities have a critical role to play in identifying emerging challenges before health systems are forced to respond to them.
"That's really the value universities add," Associate Professor Lassi says. "Doing the slow, unglamorous mapping work while everyone else is putting out fires."
Like Professor Bi, she is focused not only on generating evidence but on ensuring it informs decision-making.
Her work on reproductive, maternal, child and adolescent health has contributed to multiple World Health Organization advisory groups and global guideline development processes.
"Policy gets written whether the evidence is strong or not," she says. "Someone still has to make a decision. My job is to make sure that when they do, they are working with the best available answer, not a guess dressed up as one.”
Together, Professor Bi and Associate Professor Lassi show what research impact looks like when it is made visible: evidence becomes an early warning, a safer workplace, a more inclusive health message or a stronger policy decision.
Their work also reveals the larger Adelaide University narrative. Research does not finish when a paper is published. Its purpose is realised when people can understand it, institutions act on it and communities are better protected because of it.
1. World Health Organization, Climate Change, WHO Health Topics, accessed September 2026. WHO states that climate change is "the single biggest health threat facing humanity" and is expected to cause approximately 250,000 additional deaths annually between 2030 and 2050 from malnutrition, malaria, diarrhoeal disease and heat stress.
2. Monika Nitschke et al., "Evaluation of a Heat Warning System in Adelaide, South Australia, Using Case-Series Analysis," BMJ Open 6, no. 7 (2016): e012125. The study compared health outcomes during Adelaide's 2009 heatwave and the 2014 heatwave after implementation of the Heat and Health Warning System.
3. Susan Williams et al., "Evaluating Cost Benefits From a Heat Health Warning System in Adelaide, South Australia," Australian and New Zealand Journal of Public Health 46, no. 2 (2022): 149-154. The study estimated a benefit-cost ratio of 2.0-3.3 based on avoided hospital admissions, emergency department presentations and ambulance callouts.
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