Rising sea level puts US Atlantic coast at risk: report
June 25, 2012, 12:08 am TWN
PARIS--The sea level on a stretch of the U.S. Atlantic coast that features the cities of New York, Norfolk and Boston is rising up to four times faster than the global average, a report said Sunday.
This increases the flood risk for one of the world's most densely populated coastal areas and threatens wetland habitats, said a study reported in the journal Nature Climate Change.
Since about 1990, the sea level along the 1,000-kilometer (620-mile) "hotspot" zone has risen by two to 3.7 millimeters (0.08 to 0.15 inches) per year.
The global rise over the same period was between 0.6 and one millimeter per year, said the study by the U.S. Geological Survey (USGS).
If global temperatures continue to rise, the sea level on this portion of the coast by 2100 could rise up to 30 centimeters over and above the one-meter global surge projected by scientists, it added.
The localized acceleration is thought to be caused by a disruption of Atlantic current circulation.
"As fresh water from the melting of the Greenland Ice Sheet enters the ocean, it disrupts this circulation, causing the currents to slow down," USGS research oceanographer and study co-author Kara Doran explained.
"When the Gulf Stream current weakens, sea levels rise along the coast and the greatest amount of rise happens north of where the Gulf Stream leaves the coast (near Cape Hatteras)."
The hotspot stretches from Cape Hatteras, Northern Carolina to north of Boston, Massachusetts and also includes other big cities like Philadelphia and Baltimore.
"Extreme water levels that happen during winter or tropical storms, perhaps once or twice a year, may happen more frequently as sea level rise is added to storm surge," Doran told AFP.