Aligning local adaptation needs with ETCCDI indices in Freudenstadt, a German municipality

Abstract German municipalities are facing increasing challenges in terms of climate adaptation, not least because complex climate information is often difficult to translate into locally actionable knowledge. Although climate indices developed by the Expert Team on Climate Change Detection and Indices (ETCCDI) provide a standardized and widely used framework for describing climate variability, they are originally defined primarily from a scientific perspective and may therefore not fully reflect local information needs. This study reverses the conventional workflow, using practitioners’ perspectives as the starting point for selecting and interpreting indices. The municipality of Freudenstadt in Germany was used as a case study. Semi-structured interviews with municipal departments identified locally relevant climate-related impacts and opportunities, guiding the targeted selection of four ETCCDI indices capturing heavy precipitation, reduced snow, heat, and drought. These indices were calculated at district level using high-resolution regional climate model simulations with a resolution of 2.8 km for the period 1991–2020 and + 3 K global warming level. The results indicate an increase in heat and drought stress in the more densely populated eastern parts of the district, alongside with less frost and more frequent heavy precipitation events in mountainous areas. The experience-driven selection of high-resolution indices aligns with the perceptions of practitioners and provides a shared baseline to support dialogue and comparable adaptation planning. However, some planning-relevant climatic conditions are not fully captured by ETCCDI indices, suggesting the value of complementing them with tailored indices for a more comprehensive local assessment.