This story was originally published July 1, 2012:
DURHAM, N.C. - Sea levels in a 620-mile "hot spot" along the Atlantic Coast are rising three to four times faster than the global average, according to a new study by the U.S. Geological Survey.
The sharp rise in sea levels from North Carolina to Massachusetts could mean serious flooding and storm damage for major cities such as New York, Philadelphia, and Boston, as well as threats to wetlands habitats, the study said.
Since 1990, sea levels have risen 2 millimeters to 3.7 millimeters a year from Cape Hatteras, N.C., on the Outer Banks, to Boston, said the study, published in the journal Nature Climate Change. The global average for the same two-decade period was 0.6 millimeter to 1 millimeter per year.
Experts at the Geological Survey, along with other scientists, say that climate change and other factors will likely produce an average global sea level rise of 2 to 3 feet by 2100, said Asbury Sallenger, a USGS oceanographer who led the study, in an interview with the Los Angeles Times. The study predicts that sea levels will rise an additional 8 inches to 11 inches in the Atlantic Coast "hot spot," he said.
The main cause of recent sea level increases along the coast is the slowing of Atlantic currents caused by the arrival of fresh water from the melting of the Greenland Ice Sheet, the study said.
"Cities in the hot spot, like Norfolk, New York and Boston, already experience damaging floods during relatively low-intensity storms," Sallenger said. Accelerated sea level rise in the hot spot will raise the risk of flooding and the height of storm surges, he said.
The USGS report follows a study by the National Research Council predicting that sea levels along the California coast will rise as much as one foot in just 20 years, 2 feet by 2050 and 51/2 feet by 2100. The report says the increases are caused by climate change and by the sinking of land masses in much of California.
The study predicts that global sea levels will rise 9 inches by 2030, 18 inches by 2050, and 41/2 feet by 2100.
Sea-level rise is a sensitive subject for some political conservatives, who say that global warming is a hoax and that sea levels are not in danger of rising precipitously. The USGS study is significant because it provides data showing that sea levels have risen over the last two decades along the Atlantic Coast, regardless of the cause.
This spring, Republicans in the North Carolina legislature introduced a bill that would require sea-level rise forecasts to be based on past patterns and would all but outlaw projections based on climate change data.
Using climate change and other data, a science panel with the state Coastal Resources Commission said that sea levels along the North Carolina coast could rise an average of 39 inches by 2100. Coastal business and development interests complained to the Republican-controlled legislature, saying the projections could trigger regulations costing businesses and homeowners millions of dollars.
Sallenger called the North Carolina science panel's 39-inch prediction "totally sensible."