Sea Levels Rising Fast on U.S. East Coast - NationalGeographic

[WillyT]

Sea Levels Rising Fast on U.S. East Coast
Not clear whether human-caused global warming is to blame, experts say.
Charles Q. Choi for National Geographic News
Published June 25, 2012


The last house on Holland Island, Maryland, where 360 people lived before tides took over (file picture).
Photograph by Astrid Riecken for the Washington Post/Getty Images

<snip>

Sea level rise on the U.S. East Coast has accelerated much faster than in other parts of the world—roughly three to four times the global average, a new study says. Calling the heavily populated region a sea level rise hot spot, researchers warn that cities such as Boston, New York, Philadelphia, and Baltimore could face a more flood-prone future.


(Also see "New York, Boston 'Directly in Path' of Sea Level Rise.&quot : http://news.nationalgeographic.com/news/2009/05/090528-greenland-melt.html

Sea levels worldwide are expected to rise as global warming melts ice and causes water to expand. Those levels, though, are expected to vary from place to place, due to factors such as ocean currents, differences in seawater temperature and saltiness, and the Earth's shape.

Now it seems scientists have pinpointed just such a variance.

Analyzing tide-level data from much of North America, U.S. Geological Survey scientists unexpectedly found that sea levels in the 600-mile (1,000-kilometer) stretch of coast from Cape Hatteras (map), North Carolina, to the Boston area climbed by about 2 to 3.8 millimeters a year, on average, between 1950 and 2009.

Global sea level rise averaged about 0.6 to 1 millimeter annually over the same period.

"If you talk with residents of this hot spot area in their 70s or 80s who've lived there all their lives, they'll tell you water is coming higher now in winter storms than it ever did before," said study co-author Peter Howd, an oceanographer contracted with the USGS.

"We're now finally getting to the point where we can measure their observations with our highfalutin scientific instruments."

<snip>

More: http://news.nationalgeographic.com/news/2012/06/120625-sea-level-rise-east-coast-us-science-nature-climate-change/

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Also: USGS: Sea level in Atlantic 'hot spot' rising faster than world's - LATimes

Link: http://www.latimes.com/news/nation/nationnow/la-na-nn-sea-level-atlantic-20120625,0,5813153.story

[freshwest]

1. Seems odd it's higher in one place than another. Colder and denser? More shallower seabed?

If they're saying the ocean is, that is... Uh. Of course some areas are lower down.

[RobertEarl]

2. Ma's hitting the worst offenders?

My theory is that the Gulf Stream is getting backed up, or dammed, by the colder waters in the north. Too, could be the land is sinking. It is seaward of the Appalachians and there is a rift in the Atlantic.

[freshwest]

3. So you think the colder water, which comes off the iceberges melting in Greenland, that are less...

Saline and are said to go down deeper and power the Gulf Stream, etc. and all the way around the globe circulating, is able to do that too?

I only thought I had such weird thoughts. I was only guessing. I know of the Gulf Coast geosyncline as it was called in my college geology classes, is on the way down. but slowly. And beaches are being eroded from hurricanes and more sand is being trucked in to replace them. But big cities like parts of the NYC and eastern cities did flood during the last hurricane season, and a lot of water backed up into the rivers, etc in the NE. We also had a thread this year about global warming climate denying legislators in the southeastern states were found to be selling out their beachfront properties. And things have not really recovered i n the Gulf states after Katrina and Ike. The construction there is different now. The really big thing is if the ocean current 'conveyor belt' is slowed by an influx of cold water disrupting it. Some said it would lead to much colder winters in northern Europe and the NE and other problems. IDK, really don't.

Thanks RobertEarl.

[RobertEarl]

4. Fresh water from ice melt

.....is lighter than salt water. So when the two initially meet not only is the colder water below the warm it is also on top. In effect it is a wall from top to bottom. A porous wall, but a wall nonetheless.

There actually is an historic precedent... scientist say it has happened before. That the gulf stream was turned away by a wall of colder water. Have read there is evidence now of the gulf stream slowing down and not going as far north.

People on the east coast need to get prepared. You know insurance companies sure as heck are.

[freshwest]

5. Thanks that is so interesting. Yes, the insurance companies and a lot of people are on it.

Same would be with many things, they have the data. I'm on the west coast and we're higher up - the coastline, it seems.

I haven't heard of much erosion out here. And going inland quickly goes up. I'm at about 600 feet above sealevel but can see the water if I drive downhill.

[WorseBeforeBetter]

6. Meanwhile, in North Carolina....

Climate Politics: North Carolina House Whiffs on Controversial Sea-Level Bill

It argued that plans for the future should be based solely on historical rates of sea-level rise, despite the fact that, with rising temperatures and melting ice sheets and glaciers, it's pretty clear that sea-level rise will accelerate this century. Instead of the 39 inches recommended by the science panel, the historical method proposed by NC-20 would project a sea-level rise of only eight inches.

http://www.huffingtonpost.com/bill-chameides/climate-politics-north-ca_b_1625665.html

Developers and good ol' boy Republicans are a dangerous mix.

[HooptieWagon]

7. OK, several misconceptions here.

First, the density of liquid water changes very little with temperature, from 999g/cm^3 to 995g/cm^3 , so I dont think that is a large effect.
Secondly, melting icebergs will not raise the water level at all. Archimedes, a few thousand years ago, proved a floating body displaces a weight of water equal to its own weight. Thus, when the ice melts into water, its weight does not change, and the water level does not rise.
Glaciers are above sea level, their melting will cause a significant sea level rise.

[WillyT]

8. So If I Understand You Correctly...

If I'm already sitting in the bathtub while it is filling, and I turn off the faucets before it reaches the top of the tub... all is well.

(Icebergs <Me> are already IN the water.)

BUT...

If I fill the tub a couple of inches from the top, and THEN jump my whole wonderfulness into the tub (Greenland Ice Melt)... there will be a serious rise in water levels (in the tub).

Have I got that right?



Thank you for your more scientific explanation... I'm just in a bit of a mood tonight.

Might just go into the bathroom and test my hypothesis.

[HooptieWagon]

10. If you fill the tub to the brim, and climb in,

The water that spills over will weigh the same as you. An easy way to see Archimedes Principle; put an ice cube in a glass measuring cup. Add water until the ice is floating, and note the level. Wait for the ice to melt and become room temperature. The level will be the same, because the combined weight of icecube and water is the same as the later weight of all water. It has to... you haven't added or removed water or ice - simply allowed the ice to melt.

Melting pack ice will have an effect on changing climate patterns, but none on sea level. The threat to sea level rise is melting glaciers and continental ice. Greenland, to some extent, but mostly Antarctic continental ice, which is as much as two miles deep. Also, as the ice melts, the continent will rise, which will displace additional water causing further sea level rise.

[WillyT]

11. Well... I Was Trying To Be Ironic...

But YOUR answers have kicked ass so far.

Thank you for the straight dope.

[Wounded Bear]

9. You have to consider the land ice on Greenland and Antarctica...

If they melt and flow into the sea, it would raise ocean levels several meters.

Also the glaciers (as you mentioned), particularly in the Himalayas and Tibet.

Floating ice does not raise ocean levels, but any land based ice will.

[HooptieWagon]

12. Yes, any ice or snow on land is the threat...

not ice that is already floating.

[cherokeeprogressive]

13. Coastal erosion?

[WillyT]

14. That's Some SERIOUS Coastal Erosion

[cherokeeprogressive]

16. Yeah, time has a way of changing things...

"If you talk with residents of this hot spot area in their 70s or 80s who've lived there all their lives..." That's a long time. It's possible that almost 500 ft of erosion could have happened over the long term.

Holland Island is way out in the bay and unprotected by any surrounding geological features. The Chesapeake drains over 150 rivers. That's a lot of outflow at ebb tide. Inlets, bays, and capes are especially susceptible to erosion. It's not uncommon to find places that average 8 ft/yr over the long term. It's also not uncommon to see 75-100 feet of erosion from a single, severe storm.

I have no way of knowing how old this house is, or whether this picture was taken at high tide, during ebb tide, or at low tide. I'm guessing though that the picture was taken at high tide. That's when I would have taken it, so as to catch the most dramatic effect.

Not trying to be argumentative, just trying to add some different perspective. The link below has some really good information about erosion, which is a problem that has been troubling the Atlantic coastline for oh, just about ever.

http://dcm2.enr.state.nc.us/Maps/onslow_rate.htm

[Glassunion]

15. Sweet...

I live in PA. Soon I'll have ocean front property. $$$$