WCD Ideas: The transition from event-based storylines to conditional climate trajectories

Abstract. The recent emergence of studies using multi-year storyline simulations raises questions regarding the interpretation of the climate information they provide. We argue that these simulations can be viewed as conditional climate trajectories, extending the original event-based storyline concept while preserving its fundamental philosophy of conditioning on atmospheric circulation. The transition of storylines from assessing individual events to continuous multi-year simulations changes how the associated statistics and attribution statements should be interpreted and communicated. Therefore, in this paper, we revisit the conceptual interpretation of multi-year storyline simulations and examine the implications of viewing them as conditional climate trajectories.