East Coast May Feel Rise in Sea Levels the Most
Monday, June 8, 2009
Sea levels could rise faster along the U.S. East Coast than in any other densely populated part of the world, new research shows, as changes in ice caps and ocean currents push water toward a shoreline inlaid with cities, resort boardwalks and gem-rare habitats.
Three studies this year, including one out last month, have made newly worrisome forecasts about life along the Atlantic over the next century. While the rest of the world might see seven to 23 inches of sea-level rise by 2100, the studies show this region might get that and more -- 17 to 25 inches more -- for a total increase that would submerge a beach chair.
Scientists say the information comes from computer models, which could be wrong. And the mid-Atlantic region's ample high ground means it will probably never be as vulnerable as Louisiana and Florida.
But some are already sketching a new vision for the East Coast, as a region under siege by the ocean. In the coming decades, they say, it will probably be necessary to spend heavily to defend some waterside places -- and to make hard choices about where to let the sea win.
"There will probably be some very difficult decisions that have to be made," said Rob Thieler, a scientist with the U.S. Geological Survey. "Are there places where we should simply retreat because the cost of holding the line is unacceptably high?"
On Thursday, the governors of coastal states from New York to Virginia released an agreement on Atlantic Ocean issues, including the need to prepare for sea-level rise. The governors pledged to identify places and facilities most vulnerable to high water, including port areas, parts of the power grid and other infrastructure.
Researchers say rising seas are one of the most tangible consequences of a changing climate. They rise because they are warming, expanding in volume like a highway bridge on a summer day. And they rise because they are filling up, fed by melting ice.
In the 20th century, global seas rose about 0.07 inches per year -- a steady climb up tide gauges, even as the world debated the existence and the science of climate change.
"It doesn't matter who's causing global warming. Sea-level rise is something we can measure," said Rob Young, a geosciences professor at Western Carolina University. "You can't argue that sea level isn't rising."
And it has been rising faster in the mid-Atlantic because the land here is sinking.
Understanding this phenomenon requires thinking of the Earth as an enormous balloon. Push down in one spot on the ball's surface and surrounding areas are raised up. Glaciers did this to Earth's surface during the last ice age: they pressed down on northern North America and areas to the south tilted up, like the other end of a seesaw. Today, thousands of years after the glaciers retreated, the seesaw is tipping back the other way, and the region from New York to North Carolina is falling about six inches per century.