Investigating the unthinkable

Drought, heavy rain, heatwaves: Climate-related extremes are increasingly breaking all records. How can Switzerland prepare for unprecedented emergencies? This is what researchers have been investigating for five years in collaboration with experts from the field in the WSL Extremes research program. They present their results at the «Forum für Wissen», in the conference proceedings and a web application.

• Climate-related extreme events such as droughts, heatwaves, heavy rainfall and storms will become more frequent and more intense in future (IPCC 2023).
• In the Extremes research program, WSL researchers have developed models and refined forecasts in order to better assess the effects of extreme weather events.
• Consequences of these events can be mitigated if research, administration and practice develop strategies in advance and take appropriate measures.

In the event of a disaster, insurance companies often provide initial financial assistance. However, if prolonged and costly events such as extreme droughts become more frequent, traditional insurance models reach their limits. Therefore, the Extremes researchers collaborated with individuals from insurance companies and authorities to clarify what information and actions are necessary to cope with droughts. One Extremes initiative involved civil protection: In November 2024, the project management organized a tabletop drought exercise in the WSL lecture hall together with the Federal Office for Civil Protection (FOCP) and the Center for Security Studies (CSS) at ETH Zurich. Experts who would be deployed in disaster response, such as the police, fire departments, or cantonal command staff, played out a drought lasting one and a half year. The goals were to assess how well these institutions would response to such a situation and to identify where adjustments would be necessary.

It is helpful when there is an early warning of impending extreme weather. In contrast to heavy thunderstorms, prolonged climate phenomena such as drought can be predicted with more lead time. This allows for drought warnings up to 30 days in advance using forecasting models, which the WSL has been experimenting with for several years. This year, the federal government is launching a drought platform based on the WSL models. As part of Extremes, the researchers also enhanced the 30-day forecasts by adding bark beetle spread, forest fire risk, surface water temperatures and groundwater levels to the 30-day forecasts (Malefix project).

Extreme storms, floods, droughts and forest fires are increasing worldwide due to climate change. For years, the mountainous region of northern Chile has been suffering from extreme rainfall deficits, leading to the abandonment of large areas of agricultural land. Such events, never experienced in Switzerland, can help assess the potential impacts of extreme drought on our Alpine country. A WSL project team has characterized mega-droughts around the world in order to better understand their development and describe possible drought scenarios for Switzerland (EMERGE project, news about megadroughts).

In the Alpine region, where warming is twice as high as the global average, the consequences of global warming can no longer be overlooked. The drought of 2003 lasted from mid-April to the end of August; in the dry years of 2018 to 2020, the beech leaves were already turning autumn brown as early as July. WSL's research helps to ensure that people are prepared for even unpredictable—or even unthinkable—climatic situations.