Climate change contributions to increasing compound flooding risk in New York City

Abstract Efforts to meaningfully quantify the changes in coastal compound surge and rainfall driven flooding hazard associated with tropical cyclones (TCs) and extratropical cyclones (ETCs) in a warming climate have increased in recent years. Despite substantial progress, however, obtaining actionable details such as the spatial distribution and proximal causes of changing flooding hazard in cities remains a persistent challenge. Here, for the first time, physics-based hydrodynamic flood models driven by rainfall and storm surge simultaniously are used to estimate the magnitude and frequency of compound flooding events. We apply this to the particular case of New York City. We find that sea level rise (SLR) alone will increase the TC and ETC compound flooding hazard more significantly than changes in storm climatology as the climate warms. We also project that the return period of destructive Sandy-like compound flooding will increase by up to five times by the end of the century. Our results have strong implications for climate change adaptation in coastal communities.