Rapid intensification of recent extreme precipitation events in southern Norway under warmer climate conditions

Abstract High sub-daily intensity of extreme precipitation events in southern Norway causes landslides, debris flows, and infrastructure damage, affecting safety. Using a climate storyline approach and convection-permitting regional climate modeling, we investigate how recent rainfall extremes Gyda (12–14 January 2022), Hans (7–9 August 2023), and Bø (21–22 July 2024), could have developed under +2 K and +4 K regional warming levels and in a colder (−2 K) past climate. The average change in precipitation intensity per degree of warming for the entire events of Gyda, Hans, and Bø is 3.9 ± 0.4% K −1 , 9 ± 1% K −1 , and 19 ± 4% K −1 , while the change in maximum 1-hour intensity is 10 ± 0.7% K −1 , 15 ± 2% K −1 , and 30 ± 8% K −1 , respectively, indicating intensification exceeding the rate expected from atmospheric moisture scaling alone (~7% K −1 ). Additionally, the area extent affected by heavy precipitation of all events substantially increases with warming. Overall, extreme precipitation responses to warming depend on event-specific atmospheric processes.