Compound flooding, a severe threat to densely populated low-lying coastal areas, arises from storms causing concurrent extreme meteorological tides (storm surge and waves) and precipitation. This study analyzes the concurrence probability of these meteorological conditions using climate and ocean models. Under a high emissions scenario, the global concurrence probability is projected to increase by over 25% by 2100, with latitudes above 40° North experiencing a more than 2.5-fold increase. Changes in extreme precipitation (77%) and meteorological tides (20%) account for most of this projected increase. The dependence between precipitation and meteorological tide is a significant source of uncertainty in projections, highlighting the need to account for these effects in adaptation planning to adequately protect coastal communities.

Emanuele Bevacqua, Michalis I. Vousdoukas, Giuseppe Zappa, Kevin Hodges, Theodore G. Shepherd, Douglas Maraun, Lorenzo Mentaschi, Luc Feyen