Research Says Washington D.C. Is Slowly Sinking

New research says the land under the Chesapeake Bay region is sinking and projects that Washington, D.C., could drop by six or more inches in the next century — adding to the problems of sea-level rise.

The research says the falling land in the Chesapeake Bay region, including Washington, D.C., would exacerbate the flooding that the nation’s capital faces from rising ocean waters. The research was conducted by the University of Vermont and the U.S. Geological Survey.

For 60 years, tide gauges have shown that sea level in the Chesapeake is rising at twice the global average rate and faster than elsewhere on the East Coast. Geologists have hypothesized that land in this area, pushed up by the weight of a pre-historic ice sheet to the north, has been settling back down since the ice melted. The new study — which uses data gathered from drilling in the coastal plain of Maryland — confirms this hypothesis.

The land sinking comes from “forebulge collapse.” During the last ice age, a mile-high North American ice sheet that stretched as far south as Long Island, New York, piled so much weight on the Earth that underlying mantle rock flowed slowly outward. In response, the land surface to the south, under the Chesapeake Bay region, bulged up. About 20,000 years ago, the ice sheet began melting, allowing the forebulge to sink again.

“Now is the time to start making preparations,” said Ben DeJong, lead author of the study. “Six extra inches of water really matters in this part of the world.”