Impact of Simulated Twenty-First-Century Changes in Extratropical Cyclones on Coastal Flooding at the Battery, New York City

Abstract

his paper explores simulated changes to the cool-season (November?March) storm-surge and coastal-flooding events at the Battery in New York City, New York (NYC), during most of the twenty-first century using several climate models and a previously developed multilinear regression model. The surface wind and pressure forcing for the surge predictions are obtained from an ensemble of 6 coupled global climate models (GCM) and 30 members from the Community Earth System Model. Using the ?RCP8.5? emission scenario, both the single-model and multimodel ensemble means yielded insignificant (significance level p > 0.05) simulated changes to the median surge event (>0.61 m above astronomical tide) between a historical period (1979?2004) and the mid-to-late twenty-first century (2054?79). There is also little change in the return interval for the moderate-to-high surge events. By the mid-to-late twenty-first century, there is a poleward shift of the mean surface cyclone track in many of the models and most GCMs demonstrate an intensification of the average cyclone. There is little effect on the future surge events at the Battery because most of these storm changes are not in a region that favors more or higher-amplitude surges at NYC. Rather, projected sea level rise dominates the future simulated change in the number of flooding events by the mid-to-late twenty-first century. For example, the projections show about 23 times as many coastal-flooding events (tide + surge ≥ 2.44 m above mean lower low water; 1983?2001) in 2079 when compared with 1979, and the return intervals for some major coastal floods (e.g., the December 1992 northeaster) decrease by a factor of 3?4.