U.S. vulnerability to sea level rise

By: Dr. Jeff Masters , 4:04 PM GMT on June 23, 2009

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In the last century, sea level rose 5 - 6 inches (13 - 15 cm) more than the global average of 7 inches (18 cm) along the U.S. Mid-Atlantic and Gulf Coasts, because coastal lands there are sinking. Over 50% of the U.S. coastline is vulnerable or highly vulnerable to sea level rise, according to the Coastal Vulnerability Index (CVI) developed by the United States Geological Survey (USGS). In the U.S., relative sea level rise (the combined effects of global sea level rise plus the fact the land is sinking) is highest along the Mississippi River Delta in Louisiana, where relative sea level rises of 3.2 ft (.98 meters) have been observed during the 20th century. This is one of the highest relative sea level rises in the world. According to the NOAA Tides and Currents sea level rise interactive tool, the U.S. tide gauges that have shown the highest rates of sea level rise over the past century are at Grand Island, LA (1.8 ft rise since 1947), Galveston, TX (1.1 ft since 1957), and Chesapeake Bay, VA (0.6 feet since 1975). Alaska and some areas along the Pacific Northwest coast are at low risk of sea level rise, because the relative sea level is actually falling at present. Land in these regions is rising as it recovers from removal of the weight of the great ice sheets that covered much of North America during the last Ice Age. For example, relative sea level at Kodiak Island, Alaska has fallen by 1.1 feet since 1975, despite the fact global sea level has been increasing.


Figure 1. Twentieth century annual relative sea-level rise rates in mm/year along the U.S. coast. The higher rates for Louisiana (9.85 millimeters [mm] per year, about 3.3 ft/century) and the mid-Atlantic region (1.75 to 4.42 mm per year, 0.6 - 1.4 ft/century) are due to land subsidence. Sea level is stable or dropping relative to the land in the Pacific Northwest, as indicated by the negative values, where the land is tectonically active or rebounding upward in response to the melting of ice sheets since the last Ice Age. Image credit: Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region (data from Zervas, 2001).

U.S. Coastal Vulnerability
The Coastal Vulnerability Index (CVI) takes into account six factors:

1) The geology of the coast. Barrier islands, river deltas, and marshes are the most vulnerable to erosion and sea level rise, while steep, rocky cliff shores are the least. Sheltered bays like Galveston Bay and Tampa Bay are less vulnerable than the exposed coasts. (Note, however, that hurricane storm surges are typically higher in sheltered bays, at least for slow-moving storms).

2) How steep the land near the coast is. Gently sloping lands are the most vulnerable. In the Gulf Coast region, the slope variable has the highest risk ranking along the Louisiana coast, the Texas coast north of Corpus Christi, and the southwest Florida coast.

3) The local rate of sea level rise. The sea level is rising faster along the western Gulf of Mexico than the eastern Gulf. The highest rates of sea-level rise in the Gulf of Mexico (and in the United States) are in the Mississippi delta region (10 mm/yr, or 1 inch/2.5 years).

4) The amount of shoreline erosion going on. Most of the U.S. coast is moderately or severely eroding, and very few areas are gaining (Figure 2).

5) The mean tidal range. Shores that have a large difference between low and high tide are less likely to get a significant storm tide--the height above mean sea level of the sum of the storm surge plus the tide. For example, in a region like Maine, which has a 12 ft range between low and high tide, a storm having a 9 ft storm surge will have a storm tide below local high tide for a quarter of a tidal cycle. Shores with a very narrow tidal range (e.g., the 2 ft tidal range common along the Texas and Louisiana Gulf Coast) will get a storm tide of 8 - 10 feet with the 9 ft storm surge in the above example. Shorelines with a narrow tidal range always get high storm tides regardless of when the storm surge hits.

6) How high the waves at shore are. Obviously, shores that experience higher wave heights are at greater risk. In the Gulf of Mexico, wave energy is highest along sections of the Texas coast and on the southern tip of the Mississippi delta.

Figure 2. Shoreline change around the United States based on surveys over the past century. All 30 coastal states are experiencing overall erosion due to natural processes (e.g., storms, sea-level rise) and human activity. If the shoreline is uncolored, no data was available. Image credit: USGS, 1985, and taken from Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region).

The Coastal Vulnerability Index (CVI) web page gives detailed maps of each section of the U.S. coast, along with specific reasons why each portion of the coast was assigned the ranking it got. A brief summary:

The Gulf Coast
The Gulf Coast has 55% of its length in the "very high" or "high" vulnerability range. Fully 41% of the coast falls in the "very high" range, far more than the 28% in that category along the Pacific coast and 23% along the Atlantic coast. The region around New Orleans is the most vulnerable region of the entire U.S. coast. The Florida Panhandle, as well as the West Florida coast, are at low to moderate risk because the land is not sinking much, wave heights are lower, and the slope of the land is relatively steep near the coast. The Texas coast is considered to be at a high to very high risk because of the relatively high mean wave height, sinking land, and shallow coastal slope.

The East Coast
The East Coast has 50% of its length in the "very high" or "high" vulnerability range. The highest vulnerability areas are typically high-energy coastlines where the regional coastal slope is low and where the major landform type is a barrier island. A significant exception to this is found in the lower Chesapeake Bay. Here, the low coastal slope, vulnerable landform type (salt marsh) and high rate of relative sea-level rise combine for a high CVI value. The coastline of northern New England, particularly Maine, shows a relatively low vulnerability to future sea-level rise. This is primarily due to the steep coastal slopes and rocky shoreline characteristic of the region, as well as the large tidal range.

The Pacific Coast
The Pacific Coast has 50% of its length in the "very high" or "high" vulnerability range. Areas of very high vulnerability include the San Francisco - Monterey Bay coast and in southern California from San Luis Obispo to San Diego, where the coast is most highly populated. The highest vulnerability areas are typically lower-lying beach areas. The low risk, least vulnerable areas generally occur at rocky headlands along cliffed coasts where the coastal slope is steep, relative sea-level is falling, tide range is large, and wave energy is lower. Examples of these areas are the northern coast of Washington, Monterey, and Cape Mendocino, California.


Figure 3. The Coast Vulnerability Index (CVI) for the U.S.

References
Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region.

National Assessment of Coastal Vulnerability to Sea-Level Rise: Preliminary Results for the U.S. Gulf of Mexico Coast (USGS, 2000).

Jeff Masters

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1027. KEEPEROFTHEGATE (Mod)


ATLANTIC BASIN
AOI
10N/10W
AOI
11N/56W
Member Since: Posts: Comments:
1026. Drakoen
Quoting hurricane23:


50kt shear no chance.


Yea. We are going to be looking at a late start season. I think we may have to wait till the late July or even early August.
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Quoting jeffs713:

Its warming up, but more slowly than the gulf or Caribbean.
SSTs:


26C Isotherm (depth of the 26C layer):


TCHP for the Atlantic Basin:

Still a lot of greens and blues on the isotherm and TCHP maps, esp. over the ATL itself. I'm hoping the longer it takes to heat up, the lower the range of high winds w/ storms later on. 'Course, that presupposes that storms recurve before hitting the WCar or GOM. .. ....
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Quoting Patrap:


Is the blob going to regenerate, looking at the GOM the trough is stil there it just looks like the blob thinned out...is there any LLC
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1023. Ossqss
Quoting stillwaiting:
anyone know what time friday the geos-o rocket is scheduled to launch from the cape?????


Stillwaiting, did ya get any of that nasty storm last night?
Member Since: June 12, 2005 Posts: 6 Comments: 8188
Quoting 0741:
what we need watch to see if wave coming off afica going weaking after it leave coast


50kt shear no chance.
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Naw - Pat's just showing off - it dropped the temp to something near tolerable at Poydras and St. Charles!
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Quoting stillwaiting:
anyone know what time friday the geos-o rocket is scheduled to launch from the cape?????


Launch window: 2214-2314 GMT (6:14-7:14 p.m. EDT)

Spaceflightnow
Member Since: Posts: Comments:
Quoting Levi32:


Best I could find:

Most prominent differences are that it's warmer off of New England and in the east Pacific this year than 2004, but 2004 was warmer in the eastern Atlantic, and very slightly warmer in the Gulf of Mexico than this year, but this is only one analysis. The Caribbean was about the same temperature.

June 13, 2004:



June 13, 2009:

Look at the Indian Ocean differences 2004 -2009.
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anyone know what time friday the geos-o rocket is scheduled to launch from the cape?????
Member Since: October 5, 2007 Posts: 20 Comments: 4970
1017. KEEPEROFTHEGATE (Mod)
did ya get any rain out of that pat
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1016. Ossqss
Quoting atmoaggie:
For those of you that have Vista, I recommend a powerful magnet very near your hard drive.

Just kidding, futuremet.

And others: do NOT place a magnet near your harddrive unless you do no like your software or data.


Just for the record, it would take a very, very strong magnet to wipe a drive. It is mostly a very strong magnet itself.

If you purposely want to destroy one, use a sledge hammer repeatedly before disposal. Don't count on a magnet doing the job it probably will not do it.

Never toss out any hard drive until you completely destroy it.
Member Since: June 12, 2005 Posts: 6 Comments: 8188
Patrap - Trying to start a riot in here by showing a blob starting in the GOM? LOL
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Quoting Ossqss:


MP3's are audio only, you are talking about MP4's


oops thats what I meant, thanks!
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1012. 0741
what we need watch to see if wave coming off afica going weaking after it leave coast
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1011. Ossqss
Quoting HurricaneSwirl:


Part of their website says it converts the video to the mp3, and some of it says the audio. So does it extract both the video and
the audio, or just the audio to listen to?


MP3's are audio only, you are talking about MP4's
Member Since: June 12, 2005 Posts: 6 Comments: 8188
1010. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129902
1009. KEEPEROFTHEGATE (Mod)
Member Since: Posts: Comments:
Quoting Ossqss:
Interesting article if anyone would want to convert one of our fellow bloggers weather related Youtube videos to an MP3 :-)

Ensure you understand any applicable copyright laws if considering this item.




Part of their website says it converts the video to the mp3, and some of it says the audio. So does it extract both the video and
the audio, or just the audio to listen to?
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1007. KEEPEROFTHEGATE (Mod)
Quoting CybrTeddy:
Wow, impressive wave exiting the coast.
the flags will have to rise
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Wow, impressive wave exiting the coast.
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1005. Ossqss
Interesting article if anyone would want to convert one of our fellow bloggers weather related Youtube videos to an MP3 :-)

Ensure you understand any applicable copyright laws if considering this item.


Member Since: June 12, 2005 Posts: 6 Comments: 8188
Good Evening,

Current temperature here in PR

82 F
88 F Heat Index

And is really Hot so I can't imagine what a 100 F feels!

I really miss the low 70 F that we get most of the tropical winter.
Member Since: Posts: Comments:
Quoting stormpetrol:

Yep, I took a drive East End on Monday and it was a good rain from Bodden Town all the way to East End, right now we're having a fairly decent rain In South Sound where I live, but as you know it can being raining at your place and 300 feet away not a drop is falling.
Just finished with a good downpour up here too. My grass is finally coming back to life.
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1002. WxLogic
Quoting atmoaggie:
For those of you that have Vista, I recommend a powerful magnet very near your hard drive.

Just kidding, futuremet.

And others: do NOT place a magnet near your harddrive unless you do no like your software or data.


Hehe... got to have the disclaimer... since there's always someone that actually does it and then ask why they can't get into their OS anymore. :P
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For those of you that have Vista, I recommend a powerful magnet very near your hard drive.

Just kidding, futuremet.

And others: do NOT place a magnet near your harddrive unless you do no like your software or data.
Member Since: Posts: Comments:
Does anyone has the final ACE numbers for Andres as I would want to know the stats about how the ACE numbers compare in the Atlantic vs the Eastern Pacific this year.?
Member Since: Posts: Comments:
Quoting Chicklit:
wow, Levi that looks pretty close!


Most years do....even 2005 looks pretty close on that map....it's global and not very detailed. I'd need a better graphic to demonstrate the differences effectively. That's why I pointed out the differences.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
wow, Levi that looks pretty close!
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A little flicker way out there on Sat, but probably way too early and South for that to happen. Looks like my pick in the contest bites the dust also. Only 14 left on the list.

Member Since: June 12, 2005 Posts: 6 Comments: 8188
Quoting BahaHurican:
Thanks.

Not heating up much N of 20N so far.

Its warming up, but more slowly than the gulf or Caribbean.
SSTs:


26C Isotherm (depth of the 26C layer):


TCHP for the Atlantic Basin:

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For anyone who has vista, I strongly recommend that you download SP2. This version is much lighter and efficient.
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Update: obvious downburst gust damage around Covington. Trees down, no power, lots of branches down, trash cans with 30 pounds of trash moved 30 feet and all blown east with the deepest part of the cell forming and passing to the west.

Honestly, as much wind damage as Gustav.
On the spot, I would estimate a single 65 mph gust.
Member Since: Posts: Comments:
Quoting plywoodstatenative:
Someone have a map comparable to what the SST's in the Caribbean were like during this time of the year but back in 04?


Best I could find:

Most prominent differences are that it's warmer off of New England and in the east Pacific this year than 2004, but 2004 was warmer in the eastern Atlantic, and very slightly warmer in the Gulf of Mexico than this year, but this is only one analysis. The Caribbean was about the same temperature.

June 13, 2004:



June 13, 2009:

Member Since: November 24, 2005 Posts: 635 Comments: 26700
Tampa Bay Online:
TAMPA - The 2004 hurricane season was quiet the first two months, until Bonnie, a tropical storm, brushed through the Panhandle. Then the four-hurricane procession started. The drumbeat of hurricanes - impatient Charley, plodding Frances, savage Ivan and copycat Jeanne - spun out of the Atlantic Ocean storm factory and shot toward Florida during a rare run of atmospheric ill fortune.

Oh please, do not be a repeat.
I think we'll see something sooner than two months into hurricane season.
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Quoting stormpetrol:

Yep, I took a drive East End on Monday and it was a good rain from Bodden Town all the way to East End, right now we're having a fairly decent rain In South Sound where I live, but as you know it can being raining at your place and 300 feet away not a drop is falling.
Sounds familiar......lol

Glad u are getting some rain.
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Quoting Chicklit:

Hurricane Heat Potential
Thanks.

Not heating up much N of 20N so far.
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Quoting stormwatcherCI:
Been getting good rains in East End in the afternoon all week.

Yep, I took a drive East End on Monday and it was a good rain from Bodden Town all the way to East End, right now we're having a fairly decent rain In South Sound where I live, but as you know it can being raining at your place and 300 feet away not a drop is falling.
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Oh well, the shower activity associated with a Trop. Wave east of the South Carib Islands is losing its convection fast, under the influence of high upper level winds.
It's a shame, as we were looking forward to some more rain.
Someone have a map comparable to what the SST's in the Caribbean were like during this time of the year but back in 04?
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we reach a daytime max of 94.8 here in toronto this afternoon with a heat index of 98.1 today has been the warmest day of the summer season thus far more to come as we get into july then august
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the problem that I am seeing is the areas around the yucatan and south of jamaica are becoming extremely hot. When and if the shear drops out, it will get very interesting real fast, what I am worried about is the CV waves heating up faster than expected.
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Hurricane Heat Potential
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Quoting stormpetrol:
Its very HOT here in THE Caymans, we need some rain, but I sure don't want anything like Ivan 2004 or Paloma last year to bring it.
Been getting good rains in East End in the afternoon all week.
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TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUN 24 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 53W/54W S OF 12N MOVING W NEAR 15 KT.
THIS WAVE IS ASSOCIATED WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS.
SATELLITE IMAGERY INDICATES THE WAVE COINCIDES WITH AN INVERTED-V CLOUD PATTERN IN THE LOW-LEVEL CLOUDS. SCATTERED MODERATE CONVECTION IS FROM 7N-12N BETWEEN 48W-57W.

It looks weak and torn apart by shear but ain't dead yet...
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Quoting Chicklit:

Hi Wxhatt,
2004 was a hurricane year to remember if you lived in Central Florida...we were still recovering when 2005 and Katrina occurred.


Ya 2004 is a year I'll never forget.
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Hurricane Andrew, South Carolina, Burmese Pythons, Nuclear weapons facility. What could possibly go wrong ... ;>) - cheers

Link
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Quoting wxhatt:
Now that the blog is slow due to inactivity, it's nice to be able to get in a word edgewise. LOL

Hi Chicklit, Good Memory! :)

Hi Wxhatt,
2004 was a hurricane year to remember if you lived in Central Florida...we were still recovering when 2005 and Katrina occurred.
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Can somebody post latest SST map, latest TCHP map? Thanks.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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