The added value of yet another attribution study 

Event attribution studies, which assess whether and to what extent human-induced climate change has made extreme weather events more likely or severe, have become routine in recent years. For many regions, multiple studies now exist for the same type of extreme event, with research on heatwaves dominating in Europe and globally, while studies on heavy rainfall are the most represented ones in Asia and North America. However, significant gaps remain, particularly for small island states, which have been largely neglected by attribution research. The growing abundance of studies in certain regions and for certain hazards raises questions about the added value of additional attribution analyses, for example, extreme heat in Europe or India, or heavy rainfall in Ireland or China, where sufficient evidence already exists. While the precise definition of an extreme event can influence quantitative attribution results, recent findings indicate that the effect of different datasets often explains more variance than event definition, particularly for temperature extremes. This lecture will present these new insights, drawing on a decade of experience from World Weather Attribution, and discuss their implications for the broader field of event attribution and for proposed operational services, including when new studies are necessary and how methodological choices affect the interpretation of results.