Washington, DC sinking fast, adding to threat of sea-level rise

July 28, 2015
New research led by University of Vermont scientists Paul Bierman (left), and by his former graduate student, Ben DeJong (right), confirms that the land under the Chesapeake Bay is sinking rapidly and projects that Washington, DC, could drop by six or more inches in the next century -- adding to the problems of sea-level rise. The study also shows that this sinking land will continue, unabated, for tens of thousands of years. Credit: Joshua Brown, UVM

New research confirms that the land under the Chesapeake Bay is sinking rapidly 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.

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.

For sixty 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. And geologists have hypothesized for several decades 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—based on extensive drilling in the coastal plain of Maryland—confirms this hypothesis, and provides a firm estimate of how quickly this drop is happening. Additionally, the researchers' detailed field data make clear that the land sinking around Washington is not primarily driven by human influence, such as groundwater withdrawals, but instead is a long-term geological process that will continue unabated for tens of thousands of years, independent from human land use or climate change.

The new research was conducted by a team of geologists from the University of Vermont, the U.S. Geological Survey, and other institutions. The results were presented online July 27 in the journal GSA Today.

Geological Waterbed

Washington's woes come from what geologists call "forebulge collapse." During the last ice age, a mile-high North American ice sheet, that stretched as far south as Long Island, N.Y., piled so much weight on the Earth that underlying mantle rock flowed slowly outward, away from the ice. In response, the land surface to the south, under the Chesapeake Bay region, bulged up. Then, about 20,000 years ago, the began melting away, allowing the forebulge to sink again.

"It's a bit like sitting on one side of a water bed filled with very thick honey," explains Ben DeJong, the lead author on the new study, who conducted the research as a doctoral student at UVM's Rubenstein School of Environment and Natural Resources with support from the U.S. Geological Survey, "then the other side goes up. But when you stand, the bulge comes down again."

The new research provides the first high-resolution data from the same latitude as Washington, D.C., DeJong said, of how this forebulge has subsided—and will continue to. "Until recently, the age of the thing was really poorly constrained," he said.

To design the study, DeJong and others drilled seventy boreholes, many up to a hundred feet deep, in and around the Blackwater National Wildlife Refuge, near Washington, on the Chesapeake's eastern shore. Then he 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.

Combining this data with high-resolution LiDAR and GPS map data allowed the team—that included scientists from UVM, the US Geological Survey, Utah State University, Berkeley Geochronology Center, and Imperial College, London—to create a detailed 3D portrait of both the current and previous post-glacial geological periods in the Chesapeake, stretching back several million years. This longer view gives the geologists confidence that they have a "bullet-proof" model, DeJong says, showing that the region today is early in a period of land subsidence that will last for millennia.

Wet Feet

"Right now is the time to start making preparations," said DeJong. "Six extra inches of water really matters in this part of the world," he says—adding urgency to the models of the Intergovernmental Panel on Climate Change that project roughly one to three or more feet of global by 2100 from global warming.

"It's ironic that the nation's capital—the place least responsive to the dangers of —is sitting in one of the worst spots it could be in terms of this land subsidence," said Paul Bierman, a UVM geologist and the senior author on the new paper. "Will the Congress just sit there with their feet getting ever wetter? What's next, forebulge denial?"

Explore further: Risk of major sea level rise in Northern Europe

More information: GSA Today, www.geosociety.org/gsatoday/ar … 1052-5173-25-8-4.htm

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23 comments

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denglish
1.8 / 5 (10) Jul 28, 2015
DC was built on a swamp.

The Sea Level goes up, it goes down. There is nothing we can do about it, despite our anthropocentric fantasies.
gkam
2 / 5 (8) Jul 28, 2015
Mother Nature is slapping the faces of our Congressional crooks, corporate pimps, and goobers.
gkam
2.5 / 5 (11) Jul 28, 2015
Congressional Deniers are going to get their feet wet!
Shakescene21
3.9 / 5 (11) Jul 28, 2015
Anyone who looks at old maps can confirm that the Chesapeake Bay is getting larger as the land "erodes". Ordinary erosion is a problem but rising sea levels are probably a bigger factor.
Last month we sailed around a lighthouse that in the 1880s was on a point of land but is now hundreds of yards from the shore.
antigoracle
1.4 / 5 (9) Jul 28, 2015
What's next, forebulge denial?

Yep, that's a terrible condition. Damn you GloBULL warming!
ab3a
3 / 5 (4) Jul 28, 2015
Anyone who looks at old maps can confirm that the Chesapeake Bay is getting larger as the land "erodes". Ordinary erosion is a problem but rising sea levels are probably a bigger factor.


I've personally observed the erosion around the Chesapeake Bay because I have lived and flown airplanes in the Maryland area for more than 25 years. While I can see the erosion, I don't see a whole lot of evidence of sea level rise. I have to wonder how you think that Sea Level rise is the greater culprit of the two.
OdinsAcolyte
3 / 5 (4) Jul 28, 2015
Subsidence is not the same as rising sea level.
denglish
1.4 / 5 (10) Jul 28, 2015
I have to wonder how you think that Sea Level rise is the greater culprit of the two.

It isn't.

http://www.nodc.n...5-07.png

Since 1960, its gone up .98 inch.
rgw
2 / 5 (4) Jul 28, 2015
Anyone who looks at old maps can confirm that the Chesapeake Bay is getting larger as the land "erodes". Ordinary erosion is a problem but rising sea levels are probably a bigger factor.


I've personally observed the erosion around the Chesapeake Bay because I have lived and flown airplanes in the Maryland area for more than 25 years. While I can see the erosion, I don't see a whole lot of evidence of sea level rise. I have to wonder how you think that Sea Level rise is the greater culprit of the two.


Pseudolus clones will not get any gold from Miles Gloriosus for raging in the forum that, "The earth is sinking... very very slowly..."
rgw
3 / 5 (4) Jul 28, 2015
I am driving to DC next week. Will it still be above water, or should I book a hotel in the Appalachians?
SamB
1.5 / 5 (8) Jul 28, 2015
I have to wonder how you think that Sea Level rise is the greater culprit of the two.

It isn't.

http://www.nodc.n...5-07.png

Since 1960, its gone up .98 inch.


I wonder how you measure .01 of an inch in a substance that is always changing, moving, expanding, contracting and subsiding. Anyone?
Cripes, to measure this in a still bathtub would almost be impossible, never mind trying this feat in the ocean! The surface tension alone would defeat the measurement.
denglish
1.4 / 5 (9) Jul 28, 2015
I wonder how you measure .01 of an inch in a substance that is always changing, moving, expanding, contracting and subsiding. Anyone?
Cripes, to measure this in a still bathtub would almost be impossible, never mind trying this feat in the ocean! The surface tension alone would defeat the measurement.

Yeah, it seems preposterous, doesn't' it? It gets even weirder when they make predictions and then try to terrorize us with the predictions.

This one's a gem:
"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," said Paul Bierman, a UVM geologist and the senior author on the new paper. "Will the Congress just sit there with their feet getting ever wetter? What's next, forebulge denial?"


More of the same. These AGW people are earning their place in hell; one paper at a time.

pauljpease
3.7 / 5 (6) Jul 28, 2015
Was excited until I read it's only going to sink 6 inches in next century. Not fast enough by far!
Shakescene21
4.2 / 5 (5) Jul 29, 2015
"Subsidence is not the same as rising sea level."

@odinsaccolyte: You are correct. I should have said 'land subsidence' rather than 'rising sea level'. (although the sea level has risen a bit too.)
When you' stand on the docks in the Bay and see that high tide is much higher than when you were a boy, it's easy to think that the sea is rising, when it's mostly that the land is subsiding. I'm glad we sold our waterfront property and moved above the Fall Line.
MR166
1 / 5 (2) Jul 29, 2015
Sea levels could fall 10 meters and DC would still be sinking or is that stinking. Oh---I thought the headline was referring to DC's ethics but the article was actually referring to it's height above sea level. Sorry for the mistake.
ralph638s
2.3 / 5 (3) Jul 29, 2015
Could be the best thing that could happen to USA... ;-)
chapprg1
3 / 5 (2) Jul 29, 2015
If only. At least one positive for "global warming"
gkam
2.3 / 5 (6) Jul 29, 2015
They will be floaters and survive. The scum always comes to the top.
eachus
2.3 / 5 (3) Jul 30, 2015
I can't believe these idiots. The water level in the Chesapeake Bay has nothing, nada, zero, to do with flooding in Washington, DC. If you have ever been there, you know that the normal water level in the Potomac River is just a few feet below many roads, and the Pentagon among other buildings. Yes the basement levels in the Pentagon have been flooded many times.

To be honest some of those floods have been due to the storm surge effect connected to hurricanes. Other flooding has been due just to heavy rainfall: http://www.weathe...ood.html
Shootist
3 / 5 (2) Aug 02, 2015
Washington, DC sinking fast


I'll take whatever I can get.
antigoracle
1 / 5 (1) Aug 02, 2015
Could be the best thing that could happen to USA... ;-)

Might explain why the 2 buggers are grinning their asses off.
antigoracle
1 / 5 (1) Aug 02, 2015
They will be floaters and survive. The scum always comes to the top.

A curse that has given us, you.
gkam
2 / 5 (4) Aug 02, 2015
Why are there Deniers?

Political prejudice.

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