Flooding in Bø caused significant damage to several bridges. Access to Folkestad school became difficult after the storm. Photo: Gunnar Myhre
Quantifying changes in intensity and spatial extent of recent short-duration high-impact extreme precipitation events
New paper in npj Natural Hazards by Iris Mužić, Øivind Hodnebrog, Gunnar Myhre, Jana Sillmann, and Camilla Weum Stjern as part of CICERO’s XXN project.
We quantify changes in intensity and spatial extent of recent short-duration high-impact extreme precipitation events in southern Norway, "Gyda" (January 2022), "Hans" (August 2023), and "Bø" (July 2024) under past colder (-2 °C) and future warmer (+2 °C and +4 °C) climate. We use a climate storyline/pseudo-global warming approach and convection-permitting regional climate modelling at horizontal resolutions of 1 km and 200 m to examine changes at event, hourly, and minute scales.
Main findings:
- Extreme precipitation intensifies with warming, but at different rates depending on the atmospheric processes driving each event. In almost all cases, the increase exceeds what would be expected from increases in atmospheric moisture alone (~7% per °C of warming).
- Rainfall intensification is strongest at the shortest timescales. Per-minute and per-hour precipitation extremes increase more rapidly with warming than daily precipitation extremes.
- The spatial extent of all investigated extreme precipitation events substantially increases with warming.