title: Strong influence of El Niño Southern Oscillation on flood risk around the world.
abstract: El Niño Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability and has a strong influence on climate over large parts of the world. In turn, it strongly influences many natural hazards (such as hurricanes and droughts) and their resulting socioeconomic impacts, including economic damage and loss of life. However, although ENSO is known to influence hydrology in many regions of the world, little is known about its influence on the socioeconomic impacts of floods (i.e., flood risk). To address this, we developed a modeling framework to assess ENSO's influence on flood risk at the global scale, expressed in terms of affected population and gross domestic product and economic damages. We show that ENSO exerts strong and widespread influences on both flood hazard and risk. Reliable anomalies of flood risk exist during El Niño or La Niña years, or both, in basins spanning almost half (44%) of Earth's land surface. Our results show that climate variability, especially from ENSO, should be incorporated into disaster-risk analyses and policies. Because ENSO has some predictive skill with lead times of several seasons, the findings suggest the possibility to develop probabilistic flood-risk projections, which could be used for improved disaster planning. The findings are also relevant in the context of climate change. If the frequency and/or magnitude of ENSO events were to change in the future, this finding could imply changes in flood-risk variations across almost half of the world's terrestrial regions.
authors.affiliation: Institute for Environmental Studies and Amsterdam Global Change Institute, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands; philip.ward@ivm.vu.nl.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Ward
authors.affiliation: Institute for Environmental Studies and Amsterdam Global Change Institute, VU University Amsterdam, 1081 HV Amsterdam, The Netherlands;
authors.forename: Brenden
authors.initials: B
authors.lastname: Jongman
authors.affiliation: Water and Development Research Group, Aalto University, 02150 Espoo, Finland;
authors.forename: Matti
authors.initials: M
authors.lastname: Kummu
authors.affiliation: Climate Atmospheric Sciences and Physical Oceanography Division, Scripps Institution of Oceanography, La Jolla, CA 92093; United States Geological Survey, La Jolla, CA 92093; and.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Dettinger
authors.affiliation: Deltares, 2629 HD Delft, The Netherlands.
authors.forename: Frederiek C
authors.initials: FC
authors.lastname: Sperna Weiland
authors.affiliation: Deltares, 2629 HD Delft, The Netherlands.
authors.forename: Hessel C
authors.initials: HC
authors.lastname: Winsemius
mesh_terms: D001566:Benzocaine; D059000:El Nino-Southern Oscillation; D055868:Floods; D008962:Models, Theoretical
chemical_list: D001566:Benzocaine
keywords: El Niño Southern Oscillation; climate variability; flood hazard; flood risk; global scale