Researchers at the University of Vermont have confirmed in a new scientific paper that Washington is growing more flood-prone at a faster clip than the rest of the East Coast thanks to an irreversible sinking process that is lowering the land mass around the Chesapeake Bay.
Washington’s elevation will drop by six inches by 2100, geologists Paul Bierman and Ben DeJong determined in their research, which was released Tuesday in GSA Today, a journal published by the Geological Society of America. The sinking effect, they write, is not due to any man-made cause, but the result of “forebulge collapse,” due to the prehistoric melting of a massive glacier that once covered everything north of Long Island. The massive, mile-thick ice sheet—which melted 20,000 years ago—was so heavy that it raised the elevation of land mass to the south.
“It’s a bit like sitting on one side of a water bed filled with very thick honey,” DeJong said in a UVM press release. “Then the other side goes up. But when you stand, the bulge comes down again.”
Bierman and DeJong conducted their research by drilling 70 holes, some as deep as 100 feet, around the Blackwater National Wildlife Refuge near Cambridge, Maryland. Data collected from the exposed sedimentary layers allowed their research team to create a three-dimensional model of the Chesapeake Bay region stretching back millions of years, leading to a “bullet-proof” conclusion that Washington is sinking, and will continue to for the next several millennia.
While there’s nothing to do about the six inches Washington will lose between now and the end of the century, it has the potential to make preventable sea-level increase—that caused by man-made climate change—even worse. The International Panel of Climate Change determined in a 2013 publication that global sea levels are on course to rise by as much as 2.5 feet by 2100.
Combining climate-change-fueled sea-level increases with the Chesapeake region’s sinking predicts bad, watery news for the Washington area. An interactive sea-level map from Climate Central, an organization of scientists and journalists researching the effects of climate change, shows that a three-foot increase would drastically reshape the greater Washington area’s coastlines.
Close in, the banks of the Anacostia and Potomac rivers would feel the greatest impact of a three-foot rise, while park areas around the Tidal Basin would also diminish. The areas shaded in yellow, orange, and red are subject to increasing levels of social vulnerability as a result of environmental change.
The situation is even grimmer on the Eastern Shore, with seaside towns like Cambridge and Saint Michael’s seeing the greatest risk of being submerged, and even upriver communities like Salisbury facing a water-logged future. And Delaware’s beaches will be moving significantly inland.
If the UVM findings sound alarmist, that’s because they’re supposed to. “Six extra inches of water really matters in this part of the world,” DeJong said. “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 in terms of this land subsidence. What’s next? Forebulge denial?”