The long-term study Heat, Health, and Habitats, conducted by the Complexity Science Hub with the participation of Hannah Schuster, Axel Polleres, and Amin Anjomshoaa from WU shows that even small changes can significantly improve well-being. With global temperatures on the rise, the health impacts of heat waves are becoming an increasingly pressing concern, particularly for vulnerable populations like the elderly. The interactive map tracks the evolving heat vulnerability across Austrian regions, offering a valuable data-driven tool to understand and mitigate these risks.

Insights: Austria’s vulnerability to heat

According to the research findings, each additional day with temperatures exceeding 30°C during the summer months between 2015 and 2022 led to a 2.4% increase in mortality rates per 1,000 inhabitants across Austrian districts. “The impact was more pronounced in areas where over 25% of the population was aged 65 and older, doubling mortality rates during heatwaves,” explains Hannah Schuster from CSH and WU Vienna University of Economics and Business. Furthermore, during heatwaves, defined as a week with three or more heat days, the rise in death rates was nearly three times higher compared to single heat days.

“In 2023, only 15% of districts had a quarter of their population aged over 65. By 2050, this figure is expected to rise to 80%, indicating a significant increase in heat-related health issues,” says Johannes Wachs from CSH. This demographic shift underscores the urgent need for preemptive measures to protect public health from escalating heat risks in the coming decades.

Austria’s geographic differences

Heat vulnerability across Austria varies significantly due to climatic factors and demographics. From 2018 to 2023, the number of districts facing medium to very high heat risk expanded. Eastern Austria, especially Hollabrunn, Eisenstadt Umgebung, and Rust, recorded the highest heat stress levels in 2023, while Graz, Rohrbach, Tamsweg, Reutte, Imst, Dornbirn, and Feldkirch reported the lowest heat risk that year. Vienna has a low heat risk index overall, which is due to the low average age of the population. The districts Innere Stadt and Hietzing, however, stand out as very high-risk areas due to their older demographics.

Looking ahead, without stringent emission regulations, most Austrian districts could face very high heat risk by 2050. However, adherence to strict climate policies (RCP 2.6) could moderate risks to a medium to high range. Despite occasional cooler years like 2020, the overarching trend towards warming temperatures underscores the imperative for proactive measures against heat-related challenges nationwide.

“For example, the year 2041 in the strict regulation scenario shows significantly higher heat stress compared to the moderate regulation scenario. However, it should be noted that overall, the moderate regulation scenario is associated with higher heat stress,” Schuster says.

Powerful green

Addressing these challenges, researchers emphasize the positive impact of urban green spaces in mitigating heat-related health risks. “While local governments may not directly control global warming, expanding green spaces within cities offers effective, incremental solutions. Such investments are effective because cities can be greened piece by piece without high initial costs,” notes Hannah Schuster from CSH and WU Vienna.

Heat and health: A global concern

High temperatures not only affect our mood and overall well-being but can also pose serious health risks, even leading to fatal outcomes worldwide. This has been starkly demonstrated by recent events: the hundreds of deaths during the Hajj pilgrimage in southern Arabia, temperatures exceeding 40°C in the Balkans, 86 million people in the USA under a heat warning at the end of June, and the hottest night-time temperature ever recorded in New Delhi. Older adults are particularly susceptible to heat waves, with stark increases in mortality rates observed during periods of extreme heat.

Key Facts

Key facts

• Heat susceptibility varies significantly from region to region.

• From 2018 to 2023, the number of districts with medium and very high heat risk levels went up noticeably.

• The causes are more frequent hot days and an ageing population.

• Vienna has a low heat risk index overall, which is due to the low average age of the city’s population. However, the Inner City and Hietzing districts, which have higher proportions of older inhabitants, show that a high average population age increases the risk levels.

• The eastern parts of Austria are exposed to greater heat stress.

• In 2023, the districts of Hollabrunn, Eisenstadt Umgebung, and Rust had the highest heat stress levels for the population.

• In contrast, Graz, Rohrbach, Tamsweg, Reutte, Imst, Dornbirn, and Feldkirch had the lowest heat risk index in the same year.

• Without emissions regulation, almost every district in Austria would have very high risk levels by 2050. Under a strict climate policy (RCP 2.6), the health risk levels may remain in the medium to high range, which is partly due to the constantly ageing population.

• Despite the rising heat trend, there may be individual years with cooler temperatures (e.g. 2020), but this does not change the fact that temperatures will rise overall over time. This can also be seen in the various future scenarios. For example, the year 2041 in the strict mitigation scenario shows a significantly higher heat stress level compared to the moderate mitigation scenario. Nevertheless, it is important to note that the more moderate mitigation scenario is associated with higher heat stress levels overall.

This text is based on the original release published on the website of the Complexity Science Hub.