A new study has confirmed that the ground beneath the Chesapeake Bay is sinking, and models that the Washington, DC area is likely to subside at least six inches over the next 100 years.

Washington DC Faces Subsidence And Sea Level Rise: Study

The study authors point out that the subsiding land will significantly worsen the flooding the region faces from rising ocean waters due to global warming and melting ice sheets. The news confirming the rate of land sinking due to geological processes means that rising seas are a much greater threat to the region’s roads, wildlife refuges and military bases than had been previously anticipated.

Oceanographers have noted for more than 50 years that tide gauges are shoeing that sea level in the Chesapeake is rising at a rate over twice the global average, and more rapidly than anywhere else on the East Coast. Geologists have speculated for some time that the land in this area was pushed up by the weight of a pre-historic ice sheet to the north, and is still currently in the process of settling back down since the ice melted thousands of years ago.

The new research confirms this hypothesis, and the data can be used to develop models to predict future subsidence in the area.

The subsidence study was undertaken by a team from the University of Vermont, the U.S. Geological Survey and other organizations. It was published in GSA Today, the journal of the Geological Society of America, on Monday.

More on new study on subsidence in Washington DC area

Lead author Professor Ben DeJong from the University of Vermont and the rest of the team drilled multiple holes in the Blackwater National Wildlife Refuge near Washington DC, and studied the sediment layers. They combined the findings from the sediment with satellite scans of the area, and developed predictive models that gave a very high probability of a six-inch or greater subsidence within the next century.

“Right now is the time to start making preparations,” DeJong noted in a recent interview. “Six extra inches of water really matters in this part of the world.”

Researchers and policy analysts point out that this new data significantly increases the danger already identified by the Intergovernmental Panel on Climate Change, which projects at least a foot of sea-level rise by 2100. Another recent study by a team including ex-NASA climate scientists James Hansen, argues that the rise in sea level could be as much as 10 feet by 2050 or so.