Challenges and lessons learned from the development of Swiss climate scenarios

The latest generation of Swiss climate scenarios “Climate CH2025” were published in November 2025. The scenarios were developed by the Swiss Federal Office of Meteorology and Climatology MeteoSwiss, ETH Zurich, and Center for Climate Systems Modelling (C2SM), with contributions from the University of Bern and the University of Lausanne, and implemented under the umbrella of the National Centre for Climate Services (NCCS).

The aim of the Climate CH2025 project was to develop, update and provide the physical basis of climate change in Switzerland. The information links the past development from observations with expected changes from climate scenarios and focuses on changes in climate extremes. The impacts can be summarized in clear key messages:

• Climate change is particularly evident in Switzerland
• Extreme heat is becoming more frequent and more intense
• Soils in Switzerland are drying out increasingly in summer
• Heavy precipitation is becoming more frequent and more intense
• Precipitation is falling more often as rain instead of snow
• Many effects of climate change can be avoided or reduced through climate mitigation

A key objective of the project was to provide climate information that is both scientifically robust and actionable for a wide range of stakeholders. To achieve this, Climate CH2025 emphasized clear, accessible, and consistent communication of local and regional climate changes in Switzerland. Building on previous scenario generations, Climate CH2025 expands its range of outputs to better address the needs of stakeholders. The resulting product portfolio is designed to meet the diverse needs of different user groups. It includes a vast variety of products consisting of scientific reports, daily datasets, a webatlas, brochures, videos, and more. Each of these products was specifically tailored and communicated to a user group.

This presentation reflects on challenges and lessons learned throughout the Climate CH2025 process. These include the value of user feedback, the advantages of a standardized product design, and the importance of targeted communication.