Regional climate scenario products in a global warming level perspective. Heat indicators in Switzerland.

With ongoing climate change, national climate scenarios based on current scientific knowledge are indispensable for developing regional and local mitigation and adaptation strategies. In this context, the project Klima CH2025 currently develops the upcoming edition of Swiss climate change scenarios, facilitated by collaborative efforts involving the Swiss Federal Office of Meteorology and Climatology MeteoSwiss, ETH Zurich and further partners. Klima CH2025 will provide an updated basis of user-relevant climate information and related products containing regional and local assessments of future climate change in Switzerland. The backbone of the data production chain within Klima CH2025 is a comprehensive ensemble of CMIP-driven EURO-CORDEX climate simulations. These simulations are bias-adjusted and downscaled through quantile mapping, ensuring the reliability and accuracy of the derived climate scenarios on a localized level. By combining model simulations and observations through quantile mapping, also regional to local scale heat indicators representing the current and future climates are computed. These heat indicators portraying both current climatic conditions and projected future trends are presented in a global warming level framework. The significance of understanding heat-related extremes within a changing climate cannot be overstated. Such extremes exert direct and indirect impacts on several levels such as the human well-being and critical infrastructure. Thus, gaining insights into changes of heat extremes is crucial for formulating effective adaptation strategies and provides an important basis for decision-making across different sectors. In this contribution, our aim is to validate the representation of different heat extreme indicators formulated within the framework of Klima CH2025 and present their projected future changes for different global warming levels.