In the wake of Superstorm Sandy, scientists now have a measurement of how sea levels changed over the past 10,000 years on the New Jersey coastline.
The last time that sea levels were rising near their current rate on the state's coast -- roughly 3 to 4 millimeters per year -- was 6,000 years ago during an unusually warm period with melting ice sheets, according to a study supported by the Department of Energy, National Science Foundation and National Oceanic and Atmospheric Administration. Then, the melting spurred from a combination of factors, including orbital variations and ocean circulation.
The research confirms the current impact of climate change and provides further detail about how New Jersey is reacting to warming temperatures in comparison to other locations along the Atlantic Coast, according to the study's lead author, Benjamin Horton, an associate professor at the University of Pennsylvania. The rate of sea-level rise can vary among Delaware and New Jersey and Florida, said Horton.
Photo by: Flickr user Bob Jagendorf
"New Jersey now has the most detailed sea-level record for the last 10,000 years for anywhere along the Atlantic Coast," said Horton. The research was published in the Journal of Quaternary Science.
By examining 20-meter-deep cores taken from marshlands along New Jersey's coast, the research team determined that sea levels rose 4 millimeters per year on average from 10,000 to 6,000 years ago. That coincided with melting of the world's ice sheets.
"Now what's happening? Greenland and Antarctica are melting and could trigger similar rates of sea-level rise," Horton said.
As the climate gradually stabilized, sea-level rise tapered off -- from 6,000 to 2,000 years ago, the rate was 2 millimeters annually. Between 2,000 years ago and 1900, the New Jersey rate was 1.3 millimeters a year, the scientists said.
The last figure is noteworthy because the rate has doubled since the beginning of the 20th century, largely because of climate change, according to Horton.
From the fossil record, the researchers also determined how non-climate factors are playing into rising water levels along the state's coast. Of the roughly 3 to 4 millimeters of annual sea-level rise now, about 1 millimeter of that in New Jersey is caused by geological land subsidence, said Horton.
"We were only able to determine what that value was from going back through time," he said. The scientists made their conclusions by measuring the abundance of small organisms that are very sensitive to changes in salinity. They also used new methods, such as consideration of sediment compaction, that make the measurements more accurate than prior estimates, according to Horton.
Last year, scientists at the U.S. Geological Survey reported that sea levels along a 600-mile "hotspot" between Cape Hatteras, N.C., to north of Boston have increased three times the global average since 1990.
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500.
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