Science: Jun 25, 2012

Sea levels are rising much more rapidly along the U.S. East Coast than they are around the globe, putting one of the most expensive costs in danger of floods, government researchers report.

U.S. Geological Survey scientists call the 600 miles (965 km) swath a "hot site" for climbing sea levels caused by global warming. Throughout the region, the Atlantic Ocean is growing at an annual rate three times to four times faster than the global average since 1990, according to a study published Sunday in the journal Nature Climate Change.

It is not only a fast-paced, but at a fast pace, like a car on a highway "jamming on the accelerator," said study lead author, Ashbury Sallenger Jr., the oceanographer at the agency. He looked at sea level starting in 1950, and have noticed a change starting in 1990.

Since then, sea levels went up a total of about 2 inches (5 centimeters). But in Norfolk, Virginia, where officials scrambling to fight more frequent floods, sea level jumped a total of 4.8 inches (12.19 centimeters), the research showed. For Philadelphia, levels were 3.7 inches (9.4 centimeters), and in New York, was 2.8 inches (7.11 centimeters).

Climate change pushes up sea levels by melting ice sheets in Greenland and West Antarctica and because warmer water expands.

Computer models had long planned high levels along parts of the east coast due to changes in ocean currents of global warming, but this is the first study to show that it is already happened.

By 2100, scientists and computer models estimate that sea levels globally could rise as much as 3.3 feet (1.01 meters). The accelerated pace along the East Coast would add about 8 inches (20 centimeters) to 11 inches (28 centimeters) more, Sallenger said.

"Where do such a thing becomes important is during a storm," Sallenger said. This is when you can damage buildings and eroded coasts.

On the West Coast, National Research Council report released Thursday projected an average 3-foot (nearly 1-meter) rise in sea level in California by the year 2100, and 2 feet (0.61 meters) in Oregon and Washington. The mass of land to the north of the San Andreas Fault is expected to rise, offsetting the rising sea levels in these two states.

The USGS study suggests the Northeast would get hit harder because of ocean currents. When the Gulf Stream and its northern extension stop, the slope of the sea changes to balance against the slowing flow. This slope then push up sea levels in the Northeast. It is like a see-saw effect, Sallenger theorizes.

Scientists believe that with global warming, the Gulf Stream and other ocean currents are slowing and will slow further, Sallenger said.

Jeff Williams, a retired USGS expert who was not part of the study, and Stefan Rahmstorf, a professor of ocean physics at the Institute Potsdam in Germany, said the study does a good job of making the case for sea-level rise acceleration.

Margaret Davidson, director of the Coastal Services Center by the National Oceanic and Atmospheric Administration in Charleston, South Carolina, said the implications of the new research is "an enormous when you think about it. Somewhere between Maryland and Massachusetts, you have some bodaciously expensive property in risk. "

Sea-level projections matter in coastal states because of flood maps based on these predictions can result in restrictions on property development and affect flood insurance rates.

These estimates become a problem in North Carolina recently when Parliament proposed using historical figures to calculate future sea level, rejecting high rates of state panel of experts. The USGS study suggests even higher level than the panel estimate for 2100.

The North Carolina proposal used data from University of Florida professor Robert Dean, who found no regional differences in sea-level rise. Dean said he can not argue with the results of Sallenger the study shows accelerating sea level rise in the region, but he said that it is more likely to be of natural cycles. Sallenger said there is no evidence to support that assertion.

Science

Monday, June 25, 2012

Sea rise faster on US East than rest of globe

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