Flood risk on rise for New York City and New Jersey coast, study finds

http://www.eurekalert.org/pub_releases/2015-09/ru-fro092515.php

Public Release: 28-Sep-2015
Flood risk on rise for New York City and New Jersey coast, study finds
Researchers at 5 universities including Rutgers compare storm models from prehistoric to modern eras and find a dramatic increase in major storm occurrence
Rutgers University

Flood risk for New York City and the New Jersey coast has increased significantly during the last 1,000 years due to hurricanes and accompanying storm surges, according to a study by Penn State University, Rutgers University, Massachusetts Institute of Technology, Princeton University and Tufts University.

For the first time, climate researchers compared both sea-level rise rates and storm surge heights in prehistoric and modern eras and found that the combined increases of each have raised the likelihood of a devastating 500-year flood occurring as often as every 25 years.

"A storm that occurred once in seven generations is now occurring twice in a generation," said Benjamin Horton, a Rutgers marine and coastal sciences professor. Horton also is the principal investigator on the National Oceanic and Atmospheric Administration and National Science Foundation grants funding the research.

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Flooding heights increased 1.2 meters (3.9 feet) from the prehistoric era to the modern era, researchers found. "This is mainly due to the rising sea level. Sea levels have been rising in the modern era because of human activity," Horton said. "Sea-level rise between hurricanes raises the 'baseline' water level and makes flooding more likely."

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In the new study, researchers provided a continuous sea-level reconstruction since A.D 850. They showed that since the late 19th century sea level has risen at its steepest rate for more than 1,000 years. What does that mean for residents along the New York/New Jersey coast? "An extra 100,000 people flooded in the region during Hurricane Sandy who would not have flooded if sea level had not been rising," Horton said of the 2012 storm.

Climate scientists have established that two types of storms cause the most damage - big, slow-moving storms and smaller but higher-intensity storms - and this study found that both have significantly increased in the modern era. "What we do know is that as sea level rise accelerates into the future, we are going to have more frequent flooding," Horton said.

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