NEWS

UVM study: Washington DC sinking into sea

Adam Silverman
Free Press Staff Writer

Many people hold a low opinion of the nation's capital, or at least of many politicians in it. Now, Washington, D.C., is lowering itself to meet those expectations — literally.

New research by geologists from the University of Vermont, the U.S. Geological Survey and elsewhere shows that the District of Columbia is sinking. Land is expected to fall 6 inches or more during the next 100 years, raising flood fears and adding to worries about the effect of rising sea levels on low-lying cities.

"It's ironic that the nation's capital — the place least responsive to the dangers of climate change — is sitting in one of the worst spots it could be," Paul Bierman, a UVM geologist and senior author of a new paper about D.C.'s descent, said in a statement. "Will the Congress just sit there with their feet getting ever wetter?"

The researchers, in a study published online this week in the journal GSA Today, concluded that "this falling land will exacerbate the flooding that the nation's capital faces from rising ocean waters due to a warming climate and melting ice sheets — accelerating the threat to the region's monuments, roads, wildlife refuges and military installations," UVM announced in releasing the findings Tuesday.

Washington was founded July 16, 1790, near the confluence of the Potomac and Anacostia rivers. Although long-told tales of the region say the city named after George Washington was built on a swamp, the story is little more than urban legend, according to a 2014 essay by city historian Don Hawkins in the Washington Post.

But UVM’s study indicates Washington is likely to become a lot wetter by the year 2100.

Study results confirm a long-held hypothesis, said Ben DeJong, the report's lead author. He researched land and sea around the Chesapeake Bay while a doctoral student at UVM's Rubenstein School of Environment and Natural Resources, with support from the USGS.

Tide gauges in the Chesapeake Bay have shown for 60 years that sea level "is rising at twice the global average rate and faster than elsewhere on the East Coast," the University of Vermont said. The hypothesis: Land in the Chesapeake region that had been pushed up by the weight of a prehistoric ice sheet has been settling down again since the ice sheet melted some 20,000 years ago.

To prove the theory, scientists drilled extensively in Maryland's coastal plain — 70 boreholes, some as deep as 100 feet, in and around the Blackwater National Wildlife Refuge on the Chesapeake Bay's eastern shore.

Then DeJong and the research team "examined layers of sediment in these deep cores, using a suite of techniques to calculate the age of the sand, other rocks, and organic matter in each layer," UVM said.

Finally, geologists combined the data with maps to create detailed, three-dimensional portraits of "current and previous post-glacial geological periods" in the Chesapeake that stretched back several million years.

Taken together, UVM said, the data convinced the scientists their model is "bullet-proof."

The sinking, known as land subsidence, is just beginning, geologically speaking, and "will last for millennia," the university said.

A sinking capital could be problematic enough, but climate change adds to the concerns. The Intergovernmental Panel on Climate Change predicts a rise in the global sea level of 1 to 3 feet by 2100 due to global warming, the University of Vermont noted.

"Right now is the time to start making preparations," DeJong said. "Six extra inches of water really matters in this part of the world."

Participating in the study were scientists from UVM, the USGS, Utah State University, Berkeley Geochronology Center in California and Imperial College in London.

Contact Adam Silverman at 802-660-1854 or asilverman@freepressmedia.com. Follow him on Twitter at www.twitter.com/wej12.