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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Good Afternoon,

Hurricane Andres Left At Least One Dead; Early Start to Cape Verde Season?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Pat...I have a similar story involving your fair city the year my beloved Georgia Bulldogs won the National Championship..
Member Since: August 13, 2007 Posts: 0 Comments: 10458
Quoting Jedkins01:


if you actually think it gets hot in canada, esspecially eastern canada, you probably should just stop talking all together.


89 degrees in a north lattitude zone with dewpoints in the 60's is cold compared to summer weather on the gulf coast, esspecially with the weaker high lattitude sun


Agreed - they should've been in Tampa the last couple of weeks.
Member Since: Posts: Comments:
Hmmmmmmm,...that snare beat can lead to a Walkabout,no doubt.

Years ago I went to a NOLA Superbowl on a Tuesday the week of the Game,and came Home Sunday after it.
A Cordoba isnt a Luxury Suite,but will do in a Pinch.
Member Since: July 3, 2005 Posts: 415 Comments: 125628
Quoting Ossqss:


Try and schedule them prior to midnight:) I got crushed last night. Debris everywhere this morning throughout the neighborhood. Did you get any of that down there?

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For the month of June we've managed to squeeze out 2 named storms in the west Pacific and one in the eastern Pacific, which brings us closer to normal than to one of the most inactive Junes ever.
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Quoting Patrap:
Sanford ain't crooked...he's just crazy...


Okay..more Like Mayor Nagin then..,that I can relate too.


He hears his own personal little drummer...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
Quoting KEEPEROFTHEGATE:
you were proably better off in the hotel


if you actually think it gets hot in canada, esspecially eastern canada, you probably should just stop talking all together.


89 degrees in a north lattitude zone with dewpoints in the 60's is cold compared to summer weather on the gulf coast, esspecially with the weaker high lattitude sun
Member Since: Posts: Comments:
Sanford ain't crooked...he's just crazy...


Okay..more Like Mayor Nagin then..,that I can relate too.
Member Since: July 3, 2005 Posts: 415 Comments: 125628
Sanford ain't crooked...he's just crazy...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
I thought Illinois and Louisiana had dibs on Guvna's..?



Stories on the "Missing Link",Guvna.

Member Since: July 3, 2005 Posts: 415 Comments: 125628
There's a cyclone phase diagram for the ECMWF...
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Pat...his wife is loaded...send him a bill...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
12Z GFS is still developing a CV storm... it is starting to be very persistent about it.
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The latest rumor seems to be that Gov. Sanford was in Argentina...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
Gov.Sanford was in Houston for the Pirate Party

He owes me for Sun night though.He walked out on the Bar Bill.

Member Since: July 3, 2005 Posts: 415 Comments: 125628
Quoting extreme236:


We've had a subtropical depression form in September in the Gulf before...it did become tropical soon after, but still.


Are you talking about the TD in 2007?
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Good morning all.

Tropical Tidbit for June 24th
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Hey, press. Ya'll ever find your governor?
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Canadian Cajuns are a nice group.
Member Since: July 3, 2005 Posts: 415 Comments: 125628
Quoting presslord:
KOG...I spent a week in Toronto in July years ago...but, frankly, I didn't get out of the hotel room much ; )
you were proably better off in the hotel
Member Since: July 15, 2006 Posts: 165 Comments: 52265
FL loop


The loop looks like it is pulling away from Tampa....im confused...
Member Since: Posts: Comments:
KOG...I spent a week in Toronto in July years ago...but, frankly, I didn't get out of the hotel room much ; )
Member Since: August 13, 2007 Posts: 0 Comments: 10458
Quoting presslord:
OK....When the Canadians are issuing Heat Advisories,things have gotten out of hand...
we can get quite warm up here in southern ontario press i believe its the warmest region in canada along with the central praries the highest temp ive seen here is 37 in aug of 05 and thats without the heat index which i believe was in the mid 40c range we are just getting into the 2 hottest months of the year july and august
Member Since: July 15, 2006 Posts: 165 Comments: 52265
LOL press. You are priceless.
Member Since: September 9, 2008 Posts: 6 Comments: 3412
Do I see a future storm on the GFS? Make sure it has a low with it.
Member Since: December 21, 2007 Posts: 13 Comments: 3026
701. cg2916
3:54 PM GMT on June 24, 2009
What'choo talkin' bout, bloggers?
Member Since: December 21, 2007 Posts: 13 Comments: 3026
700. presslord
3:52 PM GMT on June 24, 2009
OK....When the Canadians are issuing Heat Advisories,things have gotten out of hand...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
699. Ossqss
3:47 PM GMT on June 24, 2009
Quoting stillwaiting:
FWF91:it should be a stormy afternoon in our area,check the visable loop you can see it building to th NW of the tpa area about to move ashore and then should develop into showers and storms over land fl visable loop


Try and schedule them prior to midnight:) I got crushed last night. Debris everywhere this morning throughout the neighborhood. Did you get any of that down there?
Member Since: June 12, 2005 Posts: 6 Comments: 8183
698. Michfan
3:40 PM GMT on June 24, 2009
Things need to pick up or im going to need more coffee this morning.
Member Since: September 7, 2007 Posts: 0 Comments: 1617
696. IKE
3:32 PM GMT on June 24, 2009
Quoting Seastep:


HWRF didn't. It actually has tracked pretty much as the HWRF forecast.

You can look at others from the past few days, but here's just one:

Link


Then I stand corrected on that model.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
695. extreme236
3:28 PM GMT on June 24, 2009
Quoting stillwaiting:



if anything forms in the GOM,it would be warm core,a STS in the GOM this time of year is highly unlikely,however a TD forming in the area would not be out of the question over the next 5-10 days,IMO.....question have we had a STS ever in the GOM in the end of june?????


We've had a subtropical depression form in September in the Gulf before...it did become tropical soon after, but still.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
694. Seastep
3:26 PM GMT on June 24, 2009
Quoting IKE:


I don't think any of them are worth a flip on the tropics in 2009.

I've read enough discussions from mets at weather offices that have stated so about how bad their performing.

Didn't the GFDL and HWRF have Andres going inland....turning north? Wrong.



HWRF didn't. It actually has tracked pretty much as the HWRF forecast.

You can look at others from the past few days, but here's just one:

Link
Member Since: September 9, 2008 Posts: 6 Comments: 3412
693. NRAamy
3:26 PM GMT on June 24, 2009
My Local Weather:
John Wayne-Orange County, California
64 °F
Overcast
Member Since: January 24, 2007 Posts: 316 Comments: 31944
692. Patrap
3:24 PM GMT on June 24, 2009
Current Conditions

Uptown, New Orleans, Louisiana (PWS)
Updated: 7 sec ago
Mostly Cloudy

93.6 F

Mostly Cloudy


Excessive Heat Warning

Statement as of 9:36 AM CDT on June 24, 2009


... Excessive heat warning in effect until 7 PM CDT Thursday...
Member Since: July 3, 2005 Posts: 415 Comments: 125628
691. KEEPEROFTHEGATE (Mod)
3:24 PM GMT on June 24, 2009
Quoting IKE:


Hey...I've got 87.8. You almost got me beat...lol.
this is our forecast

Special weather statement
Issued by Environment Canada Ontario region. 10:27 AM EDT Wednesday
24 June 2009.

Special weather statement issued for..
City of Toronto
Windsor - Essex - Chatham-Kent
Sarnia - Lambton
Elgin
London - Middlesex
Simcoe - Delhi - Norfolk
Dunnville - Caledonia - Haldimand
Oxford - Brant
Niagara
City of Hamilton
Halton - Peel
York - Durham
Huron - Perth
Waterloo - Wellington
Dufferin - Innisfil
Grey - Bruce
Barrie - Orillia - Midland
Belleville - Quinte - Northumberland
Peterborough - Kawartha Lakes
Stirling - Tweed - South Frontenac
Parry Sound - Muskoka.

High humidex values today.

Temperatures are on the rise this morning and combined with high
dewpoint temperatures will give humidex values from the mid to high
thirties through the afternoon. The highest temperatures will approach 33 degrees celcius and humidex
values may briefly reach 39.

Humidex values and temperatures will be lower in areas adjacent to
the Great Lakes due to lake breezes.

Listen for further statements. Additional information may also be
found by consulting the latest public forecast. The next public
forecast will be issued by 11 AM.

END/OSPC

Member Since: July 15, 2006 Posts: 165 Comments: 52265
690. STORMTHRILLA
3:21 PM GMT on June 24, 2009
yea its erika
689. NRAamy
3:21 PM GMT on June 24, 2009
My Local Weather:
John Wayne-Orange County, California
64 °F
Overcast
Member Since: January 24, 2007 Posts: 316 Comments: 31944
688. stillwaiting
3:20 PM GMT on June 24, 2009
FWF91:it should be a stormy afternoon in our area,check the visable loop you can see it building to th NW of the tpa area about to move ashore and then should develop into showers and storms over land fl visable loop
Member Since: October 5, 2007 Posts: 20 Comments: 4970
687. IKE
3:18 PM GMT on June 24, 2009
Quoting KEEPEROFTHEGATE:


already at 11:00 am we have surpass forcasted high of 86 at my location maybe a 90 degree or more day here with mod heat index as well could feel like a 100


Hey...I've got 87.8. You almost got me beat...lol.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
686. KEEPEROFTHEGATE (Mod)
3:16 PM GMT on June 24, 2009
Quoting hurricane2009:
Well I hope some on here dont have to be checked into a clinic for severe boredom lol

This is normal for June folks, it has been said a million times, trust me when it picks up you will wish it were quiet again.
july 10
Member Since: July 15, 2006 Posts: 165 Comments: 52265
685. KEEPEROFTHEGATE (Mod)
3:14 PM GMT on June 24, 2009


already at 11:00 am we have surpass forcasted high of 86 at my location maybe a 90 degree or more day here with mod heat index as well could feel like a 100
Member Since: July 15, 2006 Posts: 165 Comments: 52265
684. stillwaiting
3:13 PM GMT on June 24, 2009
Quoting CybrTeddy:
Watch this area closley, looks like something want's to split off from the front. SST's are warm enough to support Tropical Cyclone Development. Shear I cannot say the same. Could see an STS in the gulf.




if anything forms in the GOM,it would be warm core,a STS in the GOM this time of year is highly unlikely,however a TD forming in the area would not be out of the question over the next 5-10 days,IMO.....question have we had a STS ever in the GOM in the end of june?????
Member Since: October 5, 2007 Posts: 20 Comments: 4970
682. KEEPEROFTHEGATE (Mod)
3:10 PM GMT on June 24, 2009
Quoting CybrTeddy:
LOL That didn't take long!
000
WTPZ32 KNHC 241455
TCPEP2
BULLETIN
TROPICAL DEPRESSION ANDRES ADVISORY NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP022009
800 AM PDT WED JUN 24 2009

...ANDRES WEAKENS TO A TROPICAL DEPRESSION...

AT 800 AM PDT...1500 UTC...THE CENTER OF TROPICAL DEPRESSION ANDRES
WAS LOCATED NEAR LATITUDE 20.3 NORTH...LONGITUDE 107.7 WEST OR ABOUT
130 MILES...210 KM...WEST OF CABO CORRIENTES MEXICO AND ABOUT 230
MILES...370 KM...SOUTHEAST OF THE SOUTHERN TIP OF BAJA CALIFORNIA.

THE DEPRESSION IS MOVING TOWARD THE NORTHWEST NEAR 9 MPH...15 KM/HR.
ANDRES IS FORECAST TO CONTINUE MOVING NORTHWESTWARD UNTIL IT
DISSIPATES.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. CONTINUED WEAKENING IS FORECAST TODAY AND ANDRES IS EXPECTED
TO DISSIPATE LATER TODAY OR TONIGHT.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB...29.68 INCHES.

...SUMMARY OF 800 AM PDT INFORMATION...
LOCATION...20.3N 107.7W
MAXIMUM SUSTAINED WINDS...35 MPH
PRESENT MOVEMENT...NORTHWEST OR 305 DEGREES AT 9 MPH
MINIMUM CENTRAL PRESSURE...1005 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
200 PM PDT.

$$
FORECASTER BROWN

been finish since yesterday when it was declared a cane lol just a little slow on the response
Member Since: July 15, 2006 Posts: 165 Comments: 52265
681. scottsvb
3:09 PM GMT on June 24, 2009
Quoting stoormfury:
8n 51w invest ????


nope
Member Since: January 22, 2006 Posts: 0 Comments: 1516
680. CybrTeddy
3:03 PM GMT on June 24, 2009
Watch this area closley, looks like something want's to split off from the front. SST's are warm enough to support Tropical Cyclone Development. Shear I cannot say the same. Could see an STS in the gulf.

Member Since: July 8, 2005 Posts: 259 Comments: 23013
679. stoormfury
3:02 PM GMT on June 24, 2009
8n 51w invest ????
Member Since: August 22, 2006 Posts: 0 Comments: 2552
678. IKE
3:01 PM GMT on June 24, 2009
Quoting Orcasystems:


The proper term is... boring
Quoting Orcasystems:


The proper term is... boring


Yeah...it is boring.

Absolute yawner.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
677. IKE
2:59 PM GMT on June 24, 2009
Quoting scottsvb:
I would never consider the NAM in the tropics... only continental lows or upper wind patterns!


I don't think any of them are worth a flip on the tropics in 2009.

I've read enough discussions from mets at weather offices that have stated so about how bad their performing.

Didn't the GFDL and HWRF have Andres going inland....turning north? Wrong.

Member Since: June 9, 2005 Posts: 23 Comments: 37858

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.