Heatwave Mortality Rise Linked to Climate Change and Urban Living

As temperatures soar globally, recent studies from The University of Queensland have highlighted a stark reality: human-induced climate change is significantly increasing mortality rates during heatwaves. This revelation calls for urgent action as urban populations face a heightened risk.

Research indicates that residents in metropolitan areas are more susceptible to the dangers of extreme heat compared to those in rural regions. Associate Professor Nicholas Osborne from the School of Public Health emphasizes that these findings aim to help communities and health authorities better prepare for such intense weather conditions.

“Our results suggest heatwaves with associated periods of higher mortality will occur more often than they did in the past. These higher mortality rates associated with extreme temperature heatwaves are projected to continue and we hope our research will help communities be better prepared for heatwaves.”

Dr. Nicholas Osborne, Associate Professor, School of Public Health, The University of Queensland

Urban Vulnerability to Heatwaves

By examining over 20 years of temperature and mortality data, researchers developed a Heatwave Vulnerability Index to pinpoint the most at-risk areas in Australia. PhD candidate Patrick Amoatey noted that city dwellers, particularly those with low income, low education, diabetes, and limited healthcare access, face the highest risk of heatwave-related fatalities.

“We used an index mapping tool to assess how human populations will fare under a range of heat scenarios,” Mr. Amoatey explained, adding that the tool effectively predicted heatwave-related deaths in Australia. This pattern was evident across all Australian capital cities, home to 70% of the nation’s population.

Impact of the ‘Heat Island Effect’

The studies revealed that even mild heatwaves could lead to increased mortality in cities due to the ‘heat island effect’, where urban areas absorb and retain more heat. “We believe the risk is higher in cities because of the ‘heat island effect’, as there are more heat-absorbing surfaces like roads, buildings, and railway lines,” said Mr. Amoatey.

Drawing parallels with Greater London, where similar tools have predicted spikes in ambulance callouts and mortality during heatwaves, Amoatey suggests that Australia’s existing infrastructure could benefit from incorporating a vulnerability index to enhance community resilience.

A heatwave is defined in the study as a period of three consecutive days with maximum temperatures in the top 5% for the area.

Climate Change and Heatwave Mortality

A separate investigation by researchers from UQ and The Australian National University focused on a severe heatwave in Victoria in January 2009. During this event, temperatures soared 12-15 degrees above normal, resulting in an estimated 374 excess deaths.

“Human-induced climate change had increased the excess heatwave-related mortality in the 2009 event by 20 per cent,” Dr. Osborne stated, aligning with broader research that links climate change to rising heat-related deaths.

These studies underscore the necessity of robust public health infrastructure and workforce preparedness to manage increased healthcare demands during future heatwaves.

The findings on the Heatwave Vulnerability Index can be found in Environmental Impact Assessment Review, while the mortality and climate change study, led by ANU’s Professor Sarah Perkins-Kirkpatrick, is published in Environmental Research Climate.