The change is occurring a lot faster than in other areas of the world

Jun 25, 2012 08:01 GMT  ·  By

According to a new report, it would appear that sea levels are increasing three to four times faster along certain portions of the US East Coast than globally. The study was compiled by researchers at the United States Geological Survey (USGS).

The document, published in the June 24 online issue of the top scientific journal Nature Climate Change, covers a period stretching from 1990 to present day. Over this interval, sea levels have increased by 2 to 3.7 millimeters annually, compared to the global average of 0.6 to 1 mm per year.

The area in question stretches from Cape Hatteras, North Carolina to north of Boston, Massachusetts, and is around 600 miles (965 kilometers) in length. Scientists say the region is a so-called hotspot for sea level rise.

USGS experts behind the report also say that sea levels at this location will continue their rapid rise if global temperatures are not lowered. Global warming is currently slowing down the Atlantic Ocean circulation, which is the primary driver of East Coast sea level rise.

Increased global temperatures are increasing water temperature, salinity and density in the sub-polar north Atlantic, an area that exerts a huge influence on the speed of the ocean's circulation patterns.

“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,” explains Marcia McNutt.

“As demonstrated in this study, regional oceanographic contributions must be taken into account in planning for what happens to coastal property,” adds the expert, who is the director of the USGS.

Current projections indicate that global sea levels will increase by 2 to 3 feet (0.6 to 0.9 meters) by 2100. However, regional and local highs and lows are expected to occur, brought on by differences in land movements, strength of ocean currents, water temperatures, and salinity.

“Cities in the hotspot, like Norfolk, New York, and Boston already experience damaging floods during relatively low intensity storms,” says the leader of the project, USGS oceanographer Dr. Asbury Sallenger.

“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,” she concludes.