Rising sea levels threaten US East Coast

Jasmin Melvin, Reuters 16 Jan 09;

WASHINGTON (Reuters) - Sea levels on the United States' mid-Atlantic coast are rising faster than the global average because of global warming, threatening the future of coastal communities, the Environmental Protection Agency said on Friday.

Coastal waters from New York to North Carolina have crept up by an average of 2.4 to 4.4 millimeters (0.09 to 0.17 inches) a year, compared with an average global increase of 1.7 millimeters (0.07 inches) a year, the EPA said in a report.

As a result, sea levels along the East Coast rose about a foot over the past century, the EPA's report, commissioned by the Climate Change Science Program, said.

The EPA focused on the mid-Atlantic region because it "will likely see the greatest impacts due to rising waters, coastal storms, and a high concentration of population along the coastline," the agency said.

Higher sea levels threaten to erode beaches and drastically change the habitats of species in the area, often at a pace too fast for species to adapt and survive, the EPA said.

Communities in the area are at greater risk of flooding as a "higher sea level provides an elevated base for storm surges to build upon and diminishes the rate at which low-lying areas drain," the report found.

Floods will probably cause more damage in the future as higher sea levels gradually erode and wash away dunes, beaches and wetlands that serve as a protective barrier. Consequently, homes and businesses would be closer to the water's edge.

Rising sea levels have implications beyond the mid-Atlantic region, the report said.

Ports challenged by rising waters could slow the transport of goods across the country, and disappearing beaches could hurt resorts and affect tourism revenue, the EPA said, damaging an already fragile U.S. economy.

"Movement to the coast and development continues, despite the growing vulnerability to coastal hazards," the EPA said.

Scientists have said the rate sea levels are rising has accelerated. By the end of the century, global sea levels could be seven to 23 inches higher, the Intergovernmental Panel on Climate Change has predicted.

Federal, state and local governments should step in now to prepare for the rising seas, said the EPA along with the National Oceanic and Atmospheric Administration and the U.S. Geological Survey, who contributed to the report.

Governments should protect residents through policies that preserve public beaches and coastal ecosystems and encourage retrofits of buildings to make them higher, the agencies said.

Engineering rules for coastal areas used today are based on current sea levels and will not suffice in the future, the report said.

Flood insurance rates also could be tweaked to accommodate risk from rising sea levels, the report said.

(Reporting by Jasmin Melvin; Editing by Marguerita Choy)

Study Warns of Threat to Coasts From Rising Sea Levels
Cornelia Dean, The New York Times 16 Jan 09;

Sea level rise fueled by global warming threatens the barrier islands and coastal wetlands of the Middle Atlantic States, a federal report warned on Friday.

The report, issued by the Environmental Protection Agency, the United States Geological Survey and other agencies, is one of a series examining the potential effects of a rising sea level on the nation’s coasts.

The rise in sea level is accelerating, the report said, because warmer water occupies more space and because of runoff from melting inland glaciers and ice sheets. The Middle Atlantic States are particularly vulnerable because the rates of rise are “moderately high” there, the region is subject to storms, it is densely populated and much of its infrastructure is in low-lying areas.

The report, which is available at climatescience.gov, says that in the 20th century, rates of erosion in the region varied from 2.4 millimeters to 4.4 millimeters a year, or about a foot over 100 years. In the future, the report said, “it is virtually certain” that coastal headlands, spits and barrier islands will erode faster than they have in the past.

If sea level rises at a rate of seven millimeters a year or about two feet per century, “it is likely that some barrier islands in this region will cross a threshold,” and begin to break up, the report said. The islands forming the Outer Banks of North Carolina are particularly threatened.

The Intergovernmental Panel on Climate Change, a United Nations climate effort, estimated in its most recent report that sea level might rise by about as much as two feet by 2100. Many experts regard the estimate as optimistic.

Even a modest acceleration of sea level rise will have a negative effect on the region’s coastal wetlands, the report says, adding, “It is likely that most wetlands will not survive” a two-foot rise.

In natural environments, wetlands survive rises in sea level by shifting inland to higher ground. But in the Middle Atlantic States, the report notes, valuable infrastructure like buildings and roads stands in their way.

The report said public officials should consider the vulnerability of coastal areas and take action when necessary, for example, by limiting development in vulnerable areas. But it noted that there was great uncertainty about the timing and extent of the effects of sea level rise and that the region had conducted “only a limited number of analyses and resulting statewide policy revisions” to address the issue.