Rising Sea Levels Seen as Threat to Coastal U.S.
Manteo, N.C., residents navigate streets that were flooded by Hurricane Irene in August. Rising tides are likely to mean more frequent coastal flooding.
About 3.7 million Americans live within a few feet of high tide and risk being hit by more frequent coastal flooding in coming decades because of the sea level rise caused by global warming, according to new research.
If the pace of the rise accelerates as much as expected, researchers found, coastal flooding at levels that were once exceedingly rare could become an every-few-years occurrence by the middle of this century.
By far the most vulnerable state is Florida, the new analysis found, with roughly half of the nation’s at-risk population living near the coast on the porous, low-lying limestone shelf that constitutes much of that state. But Louisiana, California, New York and New Jersey are also particularly vulnerable, researchers found, and virtually the entire American coastline is at some degree of risk.
“Sea level rise is like an invisible tsunami, building force while we do almost nothing,” said Benjamin H. Strauss, an author, with other scientists, of two new papers outlining the research. “We have a closing window of time to prevent the worst by preparing for higher seas.”
The project on sea level rise led by Dr. Strauss for the nonprofit organization Climate Central appears to be the most elaborate effort in decades to estimate the proportion of the national population at risk from the rising sea. The papers are scheduled for publication on Wednesday by the journal Environmental Research Letters. The work is based on the 2010 census and on improved estimates, compiled by federal agencies, of the land elevation near coastlines and of tidal levels throughout the country.
Climate Central, of Princeton, N.J., was started in 2008 with foundation money to conduct original climate research and also to inform the public about the work of other scientists. For the sea level project, financed entirely by foundations, the group is using the Internet to publish an extensive package of material that goes beyond the scientific papers, specifying risks by community. People can search by ZIP code to get some idea of their own exposure.
While some coastal governments have previously assessed their risk, most have not, and national-level analyses have also been rare. The new package of material may therefore give some communities and some citizens their first solid sense of the threat.
Dr. Strauss said he hoped this would spur fresh efforts to prepare for the ocean’s rise, and help make the public more aware of the risks society is running by pumping greenhouse gases into the air. Scientists say those gases are causing the planet to warm and its land ice to melt into the sea. The sea itself is absorbing most of the extra heat, which causes the water to expand and thus contributes to the rise.
The ocean has been rising slowly and relentlessly since the late 19th century, one of the hallmark indicators that the climate of the earth is changing. The average global rise has been about eight inches since 1880, but the local rise has been higher in some places where the land is also sinking, as in Louisiana and the Chesapeake Bay region. READ THE REST OF THE ARTICLE