Once upon a future heatwave: A practical storyline chain from existing climate data to stakeholder engagement

With ongoing global warming, the occurrence of unprecedented, record-breaking heat extremes steadily rises. Storylines, or tales of future weather, are an increasingly popular climate communication strategy that describe how specific, individual events may arise and how severe they may become under different background climates. By focusing on plausibility rather than probability, they can help stress-test current policy and infrastructure, and support adaptation planning and heat-risk preparedness. What remains less developed is a practical workflow for building event-based storylines and bringing them into stakeholder discussions. Here, we present a readily applicable chain of methodological steps for constructing stakeholder-oriented tales of future weather using only existing simulation output and observational datasets. The chain incorporates Global Warming Scaling and ensemble mining to identify plausible future years of extreme heat in climate-model projections by matching specific indices derived from scaled observations. We apply the method to the EURO-CORDEX ensemble to assess heat extremes in a future Belgian climate corresponding to 2°of global warming. From the mining results, an example event is chosen and used as input for impact modeling, after which model outputs are translated into a coherent and communicable tale. This tale is presented to national stakeholders as part of an iterative development process aimed at further co-producing the storyline prior to its broader dissemination. We present results from a first workshop with city officials and emergency coordinators, which successfully launched an ongoing dialog between stakeholders and scientists about the broader use of storylines as an accessible tool for climate adaptation.