Sea levels along much of the East Coast, one of the most costly coastlines, are increasing three to four times more rapidly than the global average.
The 600-mile coastal zone, from Cape Hatteras to just north of Boston, has seen sea levels rise by 2-3.7 millimeters per year since 1990, according to a new United States Geological Survey study. The global average is less than 1.0 millimeter per year for the same time period.
"Many people mistakenly think that the rate of sea level rise is the same everywhere as glaciers and ice caps melt, increasing the volume of ocean water, but other effects can be as large or larger than the so-called 'eustatic' rise," USGS Director Marcia McNutt said. "As demonstrated in this study, regional oceanographic contributions must be taken into account in planning for what happens to coastal property."
By the end of the 21st century, global sea level is expected to increase by 2-to-3 feet, according to the USGS study. Land movement, ocean current strength, water temperatures and salinity will determine how quickly the increase occurs.
"Cities in the hotspot, like Norfolk, New York, and Boston already experience damaging floods during relatively low intensity storms," said Dr. Asbury (Abby) Sallenger, USGS oceanographer and project leader. "Ongoing accelerated sea level rise in the hotspot will make coastal cities and surrounding areas increasingly vulnerable to flooding by adding to the height that storm surge and breaking waves reach on the coast."
The study, published June 24 in Nature Climate Change, comes less than a month after the 2012 CoreLogic Storm Surge report putting the New York metropolitan area at greater risk for hurricane damage.
There are more than 4 million homes across the country at risk from flood damage related to hurricanes, totaling more than $700 billion in potentially vulnerable property, according to the storm surge report. The majority of those homes, 2.2 million worth more than $500 billion, are located along the Atlantic Coast. The remaining 1.8 million homes, worth $200 billion, are on the Gulf Coast.
Hurricane season in the Atlantic begins June 1 and ends Nov. 30, according to the National Weather Service. The Eastern Pacific hurricane season begins May 15 and also ends Nov. 30.