Sea-level rise may swamp Washington, D.C.

Sea-level rise may swamp Washington, D.C.

By Dan Vergano, USA TODAY, November 23, 2011

Washington, D.C., rose from swampy river banks, and thanks to global warming, the good ol' days may be set to return. Sea-level rise may swamp some Washington D.C., monuments by 2150, a study suggests, unless levees gird the nation's capital.

CAPTION

Architect of the Capitol

"A (sea) level rise is an inevitable future for Washington, D.C.," says the Risk Analysis journal led by civil engineer Bilal Ayyub of the University of Maryland, adding, "that would impact the city even with a relatively small rise."

So, the study analyzes the effects of sea level rise expected under various scenarios used in the 2007 Intergovernmental Panel on Climate Change report, from 2043 to 2150 for the nation's capital. Then the study overlaid the resultant sea-level rise on depth maps of the region, home to the Washington Monument, Lincoln Monument, White House and U.S. Capitol, among other attractions.

Depending on the amount of greenhouse gases pumped into the atmosphere by burning fossil fuels, the atmosphere will warm enough to trigger anywhere from a 4-inch sea level rise by 2043, on the low end, to more than 16 feet by 2150, on the high end.

"Even using a modest (sea-level rise) of 0.1 m (4 inches), the analysis of the data layers shows a relatively negative impact on the city. A total of 103 properties will be flooded," at a cost of $2.1 billion, says the study. "Above these levels, the numbers become staggering," it says next.

At the high end of sea level rise, 73 monuments and museums along the National Mall would be affected by 2150, along with hundreds of buildings, and land where 103,000 people now live, says the study, if nothing is done. The Lincoln Monument is on its own island in the maps at this point.

Concludes the study:

Decisions must be made in the near future by lawmakers or city planners on how to reduce the impact of and adapt to SLR (sea-level rise). A planned retreat is not an option when dealing with SLR in such an important area. City planners have to decide whether to build countermeasures to keep the city from flooding or to accommodate the SLR either by modifying land use regulations or by reducing current financial investments in the affected area. A "do- nothing" approach would directly lead to irrevocable losses. A short-term solution, like creating a small flood barrier, may give the city time to examine this challenge and produce cost-effective solutions. Cost-effective methods to deal with SLR should be developed, and long-term solutions that extend well into this millennium are necessary.

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