Extreme heat and drought events require more systematic risk assessment

The simultaneous extreme heat and drought have consequences in various areas, for example the economy, health and food production. Additionally, due to complex socio-economic linkages, such extreme events can have ripple effects, researchers from the University of Zurich have shown. More systematic risk assessments are needed to make affected regions more resilient.

In many parts of Europe, summer 2022 was brutal: long periods of drought combined with historic temperatures. Heat waves, water shortages and forest fires particularly affect southern, western and central Europe. These mutually reinforcing extreme weather events affect a wide range of sectors and systems – healthcare, agriculture, food manufacturing, energy supply and ecosystems, as well as the economy and society at large.

Significant financial losses due to extreme heat and drought

To better understand the consequences of these extreme climatic events in different regions, researchers from the Department of Geography of the University of Zurich (UZH) analyzed eight extreme heat and drought events in Europe, Australia and Africa that occurred during the 20 last years. In addition to examining the direct and indirect consequences for various sectors and systems, they also studied the impact of responses to such events. “The financial losses, for example, can be substantial,” says Laura Niggli, first author of the study. “In the cases studied, they ranged from several hundred million to several billion US dollars.” In extreme cases such as the 100/2020 Australian bushfires, losses have reached approximately 100 billion US dollars, which is equivalent to more than 5% of Australian GDP.

Additional damage due to cascading effects

As researchers show, the effects of simultaneous heat and dryness are not limited to their individual direct effects on different areas. “We have identified an interconnected web of sectors that interact directly and indirectly, resulting in additional loss and damage in several other sectors, in particular health, energy, agriculture and food supply,” explains doctoral student Niggli. It is this multi-layered interconnection that makes extreme event risks so complex and critical. Cascading effects ripple through many sectors and can have far-reaching consequences for critical systems. “Simultaneous extreme weather conditions are potentially capable of destabilizing entire systems important to society, such as global trade,” Niggli points out.

The analysis also shows that the measures Adaptation responses to extreme heat and drought episodes were mostly reactive and limited in scope. In several cases, the scientists found evidence of misalignment of measures: that is, actions taken by one sector sometimes had negative effects on other sectors, in particular on the sectors of the energy and water, economy, society, tradition and ecosystems.

A more systematic risk assessment for better adaptability

Researchers argue that in the future, risk assessment should not only take take into account the consequences of extreme events on individual sectors, but should systematically take into account the interdependence of sectors and systems. This would help improve the adaptability and resilience of the affected regions. “This is particularly crucial because in the future we are likely to see unprecedented combined extreme events with cascading effects surpassing all previous historical instances. These effects need to be carefully analyzed to support the planning of adaptive and reactive measures,” says UZH Professor of Geography Christian Huggel, who led the study.

As the As the climate warms, episodes of extreme heat and drought will occur more often, be more intense and last longer. In order to mitigate this growing risk to society, in addition to scaling up efforts and investments in adaptation to climate extremes, cross-sectoral and increasingly international cooperation will be required.

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