As state Rep. Pat McElraft prepares this week to unveil compromise language on a bill to slow down the science of sea-level forecasting in North Carolina, a new study by the U.S. Geological Survey finds that the rate of sea-level rise is increasing several times faster on the northern Atlantic Coast from Boston to Cape Hatteras than around the world as a whole.
The rates are increasing up to four times faster along portions of the U.S. Atlantic coast than globally, according to a new U.S. Geological Survey report published in Nature Climate Change.
According to a news release issued Sunday, since about 1990, the sea-level rise in the coastal zone between Cape Hatteras to north of Boston has increased between 2 and 3.7 mm per year, compared to 0.6 to 1 mm per year globally.
Global sea level is projected to rise 2 to 3 feet or more by the end of the 21st century, but will not climb at the same rate everywhere. Differences in land movements, strength of ocean currents, water temperatures and salinity can affect sea level highs and lows, the release states.
The studys lead author, Asbury Sallenger Jr., an oceanographer at the agency, looked at sea levels starting in 1950, and noticed a change beginning in 1990.
The study focused on establishing whether a hotspot of accelerated sea-level rise existed along the northeast coast.
We detected that a statistically significant acceleration hotspot was present, Sallenger wrote in an email to The News & Observer on Sunday. This acceleration refers to increasing rates of sea level rise, not to the rate of sea level rise alone.
McElraft, a Republican from coastal Carteret County, sponsored a bill passed by the House last year to modify state setback requirements for some coastal properties. The Senate rewrote her bill, using it in an effort to nullify scientific predictions that the rate of sea-level rise along the North Carolina coast will accelerate later in this century and that the state can expect an increase of 39 inches in the sea level by 2100.
The House unanimously rejected the Senate version at the request of McElraft, and she chaired a House-Senate conference committee that produced compromise legislation last week.
McElraft told The Associated Press that the new bill, to be introduced this week, dropped the controversial Senate language that would have required any forecasts to be based solely on historic trends. She said the revised measure would bar state agencies from using the 39-inch prediction made by a panel of scientists for the Coastal Resources Commission, and direct the commission to conduct more studies during the next three or four years.
Since 1990, sea levels have gone up globally about 2 inches. But in Norfolk, Va., where officials are scrambling to fight more frequent flooding, sea level has jumped a total of 4.8 inches, the research showed. For Philadelphia, levels went up 3.7 inches, and in New York City, it was 2.8 inches.
The accelerated rate along the East Coast could add about 8 inches to 11 inches more, Sallenger said. Climate change pushes up sea levels by melting ice sheets in Greenland and west Antarctica, and because warmer water expands.
USGS: Study first proof of rise
Computer models long have projected higher levels along parts of the East Coast because of changes in ocean currents from global warming, but this is the first study to show thats already happened.
I suspect that the additional amount will first become noticeable during storms by adding to the vertical reach of waves and storm surge on the coast, Sallenger wrote. Hence, storms in the future with the same meteorological characteristics as today could have greater impact within the hotspot.
The USGS study suggests the Northeast would get hit harder because of ocean currents. When the Gulf Stream and its northern extension slow down, the slope of the seas changes to balance against the slowing current. That slope then pushes up sea levels in the Northeast. It is like a see-saw effect, Sallenger theorizes.
On the West Coast, a National Research Council report released Friday projects an average 3-foot rise in sea level in California by the year 2100, and 2 feet in Oregon and Washington. The land mass north of the San Andreas Fault is expected to rise, offsetting the rising sea level in those two states.
The Associated Press contributed
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