The importance of (natural) variability for present and future extreme precipitation risk

The statement that precipitation variability matters will not surprise anyone. Yet, in this seminar I hope to provide some new perspectives on just how vital past, present, and future precipitation variability is for current and future extreme precipitation risks and impacts. Extreme precipitation variability contributes to extreme precipitation disaster risk in multiple ways. I will demonstrate the driving role of forced change in extreme precipitation variability for future record-breaking or -shattering probability increases. The RAINETM effect: Rareness-Amplified INtensification of Extremes, is a particularly relevant, yet highly uncertain, aspect of extreme precipitation change, especially in a record-breaking context. I will outline this concept and present work-in-progress on constraining RAINE-estimates. After this rather statistical discussion, I will dedicate the last part of the seminar to a more practical approach to climate risk. When it comes to real-world impacts, the relevant quantities to look at are local probabilities of breaking the standing record, i.e. conditional record-breaking probabilities. Given the dependence of local records on historical weather, (unforced) natural variability plays a key role in shaping present and future precipitation risk – both from a statistical and a social point of view. I will present a pragmatic framework for the assessment of real-world local “extreme precipitation disaster potential” conditional on historical observations.