[A-CG35] Projection and detection of global environmental change

[ACG35-06] Global exposure to river flooding in the CMIP6 future projections

*Yukiko Hirabayashi¹, Masahiro TANOUE², Orie Sasaki¹, Xudong Zhou³, Dai Yamazaki³ (1.Shibaura Institute of Technology, 2.National Institute for Environmental Studies, 3.Institute of Industrial Science, The University of Tokyo)

Keywords:global warming, river flood, exposure

Flood risk is changing drastically worldwide, associated with socioeconomic growth and climate change. Global flood risk assessments have investigated the populations and assets potentially exposed to future flooding, based on the multiple atmosphere-ocean general circulation model (AOGCM). Here, global exposure to river flooding by a new generation of climate models, the collectively known as Coupled Model Intercomparison Project Phase 6 (CMIP6) showed that potential flood exposure will increase induced by future climate change. Increased potential flood exposure due to warming was observed in Asia, North America, and Africa, whereas exposure was stable or lower at higher specific warming levels (SWLs) in Europe and North Africa. In snow dominant rivers, projected flood peak was earlier and lower due to decreased snowmelt flood, causing decrease in potential flood exposure. The increase in flood exposure at the end of 21st century was high in Africa and Asia, particularly with 3℃ warming (1.7-fold and 1.5-fold higher than the average of 1971–2000, respectively) only due to climate change, reflecting a significant increase in flooding. We also demonstrated that the spatial patterns of the multi-model median signs of change and potential flood exposure in the CMIP6 were similar to those estimated by CMIP5. Moreover, the consistent projections of models from the same institute suggest the potential to reduce uncertainties caused by model differences. The robustness of the flood projection between CMIP5 and CMIP6 supports the efforts to make decision needed to adapt to climate impacts and mitigate greenhouse gas emissions.