If risks cumulate – Analysis and management of cumulative climate risks in Switzerland

The Swiss Federal Office for the Environment (FOEN) had conducted eight case studies in Switzerland to assess climate change related risks and opportunities. The synthesis report of these case studies (Köllner et al., 2017) serves as a basis for the further development of the Swiss climate adaptation strategy but also identified knowledge gaps and missing planning tools among others for risks with a very low probability of occurrence and potentially very high impacts for society and/or the environment. Such risks often derive from a combination or cumulation of risks through process chains or from an exceptional accumulation of meteorological extreme events within a short time period.

In order to fill these knowledge gaps, FOEN funded a three-year research project, which was launched in spring 2019. It aimed at analyzing plausible ‘cumulative’ climate-triggered risks in Switzerland and related management strategies in response to such risks. In a first phase, the project reviewed the terminology and available methods for the analyses of cumulative climate-triggered risks. In a next step, the project analysed two related case studies in Switzerland, by including a stakeholder process.

Is it possible, that a meteorological Event can – in a worst case – lead to the loss of the protective function of a forest? To answer this questions, experts have analyzed the possible impacts of combined extreme event in the Val Mesocina.

In an extensive survey, 29 experts from practice and administration estimated the likelihood for a loss of protective function in different hazard-scenarios.

A detailed description of the case study and the results of the survey including figures fo all questions can be found here (in German). A factsheet summarizing the results is available here in German, Italian and French.

Is it possible, that subsequent years with estensive heat and drought periods can push human health, the water or energy supply, or other relevant systems of a city to the limit? To answer this questions, experts have analyzed the possible impacts of combined extreme event in Basel.

Based on structured interviews with experts from different sectors, process diagrams were drawn to characterize the potential impact of such a combined heat and drought extreme evant. The results were used to characterize possible worst-case scenarios and formulate adaptation options.

A factsheet describing the key results of the case study can be found here in German, French and Italian.

A report describing the methods used in the case studies and summarizing their potential and limitations can be assessed here (in German).

General conclusions and recommendations are available here (in German).

Raphael Neukom