Potential impacts of sea-level rise on the Atlantic and the gulf of Mexico Coast of the United States

We made projections of relative sea-level rise, horizontal inundation, and the associated impacts on people and infrastructure in the Atlantic and the Gulf of Mexico coast of the United States. We first estimated the relative sea-level rise by 2100 in the study area by using (1) rates of subsidence in different localities derived from historical tide gauge observations and (2) rates of global sea-level rise from the semi-empirical model developed by Rahmstorf (2007). The range of sea-level rise projections mainly reflects equal contributions of spatial variability (due to subsidence) and the range of projected greenhouse gas scenarios, the range of projected temperature change (from global climate models) for a given scenario, and uncertainty in the semi-empirical model itself. Using the USGS 30-m National Elevation Dataset, projected sea-level rise, and local subsidence estimates, we mapped the horizontal inundation in the region, and examine the different land use categories in the inundated zones. Finally, we overlaid the inundation maps with census block data to determine the number of people and housing units located in the area vulnerable to future sea-level rise. Analysis results were summarized by state to indicate spatial variability and facilitate information usage by stake holders. In total, 31-53 thousand km² of land will be inundated depending on different sea-level rise scenarios; 3.8 - 6.6 million people and 1.8 - 3.2 million housing units are at risk of inundation by future sea-level rise. The risk is not distributed evenly. In general, northern states are less vulnerable because of relatively small future sea-level rise and the steep coastal terrain, whereas southern states are more vulnerable because of the higher sealevel rise, low elevation and flat terrain profile. However, some northern states such as New York and New Jersey have highly developed coast. As a result, even moderate amount of inundation area may lead to large number of people and housing units at risk of future sealevel rise.