Towards a storyline approach for representing uncertainty in climate change flood losses: A case study for Europe.

Abstract: Climate change will increase the frequency and intensity of many extreme weather events at the global scale. This has implications for societal exposure to these hazards and resultant financial losses. One such hazard is that of flood. There is, however, uncertainty in the spatial distribution of changes in river and surface water flood risk, which relates to different projections of climate change’s impact on large scale weather patterns. This uncertainty is typically quantified using an ensemble of climate models and assessing the range of potential hazard intensities for a given climate forcing. An alternative way is to use “physical storylines”, with each storyline representing different plausible future shifts in weather patterns for a given level of climate change.

Here, we present a range of potential physical storylines for flood hazard in Europe based on the output of three climate models, each showing distinct spatial patterns of precipitation and temperature trends. We use these climate model outputs to drive a hydrology model to assess trends in streamflow. The spatial distribution of the climate change signal is extracted through a pattern scaling approach, which scales the precipitation and streamflow changes with changes in global mean surface temperature. This is used to derive climate change adjustments (positive or negative), which are then used to create change factors to adjust the frequency and intensity of a multi-thousand year time series of extreme events. We use these “climate-conditioned event sets” in an industry standard catastrophe model to estimate changes in financial loss from flood events for the different physical storylines. This provides a novel way of exploring uncertainty in our projections of the impact of climate change on flood losses, and useful insights about future surface water and river flooding for the financial, insurance, and development sectors.
 

Biography: Anya joined JBA Risk Management’s Climate Change team in 2022 where she has worked to improve the understanding of changing flood hazard and risk under different climate change scenarios both within the UK and globally. Prior to joining JBA, Anya received a BSc in Geography from Newcastle University and a master’s degree in Earth Sciences from Uppsala University, Sweden. During her studies, Anya focused on changing polar environments and palaeoclimatology. For her master’s dissertation, this included reconstructing past climate in the Channel Islands with a focus on changing circulation patterns during the last glacial period.