Sea Level Rise in the New York CIty Metropolitan Area

Abstract

Sealevelriseduetoclimatewarming willamplifycoastalhazards such as stormsurges, beacherosion, and lossof wetlands. sea level in the NewYork metropolitan region has risen steadily by 22-39 cm dUring the 20th century. Projections basedon bothhistorictrendsand climatemodelsimulations (Hadley Centre, UK and CanadianCentre for Climat~ Modelling and Analysis) suggest that regional sea levelscouldclimbanother18-60cm by the 2050s and 24-108 cm by the 2080s,over late20thcenturylevels. The retumperiodof the 100-year stormfloodcouldbe reduced, on average, to 19-68yearsby the 2050sand 4-60 yearsby the 2080s, resulting in morefrequent damaging coastal floods.Around 38% of the landsurfaceof saltmarsh islands has disappeared in Jamaica Bay, New York City between 1974 and 1999, due to the interaction of a number of anthropogenic factorsand sea level rise. Giventhesestresses, the saltmarshes are not likelyto surviveaccelerated sea levelrisewithouturgentremedial action. The modest sea level change projected for the next 20-30 years provides a graceperioddUring which coastal managers, planners, and other stakeholders can develop appropriate mitigation/adaptation strategiesand policies to cope with longer-term sea level rise. INTRODUCTION Sea level rise, due to global warming, is an example of a slow-onset coastal hazard (shoreline changes are another), in contrast to rapid-onset hazards, such as flooding by storm surges and waves, or tsunamis (giant sea waves triggered off by earthquakes, volcanic eruptions, or submarine landslides. The accelerated sea level rise could lead to permanent inundation of low-lying coastal regions (particularly coastal wetlands, parts of major deltas, and beaches), as well as more frequent flooding episodes, and worsening beach erosion (IPCC, 200la,b). lCenter for Climate Sytems Research (Columbia University, GISS 2880 Broadway, New York, NY 10025, vgornitz@giss.nasa.gov