January 19, 2009
The Seas are Rising
EPA reports 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. 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. As a result, sea levels along the East Coast rose about a foot over the past century. EPA Sea Level Assessment and Adaptation Report
The IPCC's Fourth Assessment Report indicated that the rate of sea level rise has accelerated and, by the end of the century, global sea levels could be seven to 23 inches higher. Readers should remember that this IPCC estimate excludes the contribution of Antarctic and Greenland ice because of uncertainties about ice stability and dynamics at the time the Working Group I report was drafted. In the last two years, additional scientific research has begun to identify a more reliable range of sea level rise associated with those areas of ice, dramatically increasing the estimate of likely global sea level rise by 2100.
EPA had 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." Higher sea levels erode beaches and drastically change the habitats of species, often at a pace too fast for species to adapt and survive. 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." 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 and more likely to be damaged in extreme storm events that other scientists predict are increasing with global warming.
Rising sea levels have implications beyond the mid-Atlantic region. Ports challenged by rising waters could slow the transport of goods across the country, and disappearing beaches could hurt resorts and affect tourism revenue, damaging an already fragile U.S. economy.
EPA, NOAA, and USGS recommend:
- Federal, state and local governments should step in now to prepare for the rising seas
- Governments should protect residents through policies that preserve public beaches and coastal ecosystems and encourage retrofits of buildings to make them higher
- Engineering rules for coastal areas be revised because those used today are based on current sea levels
- Flood insurance rates also could be adjusted to accommodate risk from rising sea levels
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