Real-time Attribution of the Influence of Climate Change on Extreme Weather Events: a Storyline Case Study of Hurricane Ian Rainfall

As the Earth continues to warm due to human greenhouse gas emissions, there is a growing need to efficiently communicate the effect that global warming has on individual extreme weather events. Using a storyline approach, we present a rapid attribution of the increase in rainfall over Florida during Hurricane Ian in 2022 due to climate change as a case study. By comparing ensemble hindcast simulations of the "storm that was" to the "storm that might have been without global warming", we find that extreme accumulated rainfall amounts associated with Hurricane Ian increased by 18%, far in excess of what would be expected by Clausius–Clapeyron scaling. The study offers a blueprint for rapid operational climate change attribution statements about extreme storms and other very rare weather events.