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Sun Jan 13, 2013, 03:21 PM

What global warming and rising sea levels mean for New Orleans

WARNING: This column contains science. It might considered inappropriate or offensive by certain members of our congressional delegation and others who call themselves conservative. Ideological discretion is advised.

The South Louisiana Flood Protection Authority-East recently received a highly anticipated report on the future of the East Land Bridge -- that strip of marsh and ridge line between Chef and Rigolets passes that serves as the roadbed for U.S. 90. The land bridge is a top priority; it's the last remaining natural speed bump between Lake Pontchartrain and hurricane storm surges rolling in from the Gulf. And as we all now know, storm surge in the lake can flood communities from New Orleans to Madisonville to LaPlace.

But like the rest of the Mississippi River delta, the land bridge has been sinking and crumbling. So the authority hired the West Coast engineering firm of Ben C. Gerwick to tell it how long the land bridge has to live, what happens if it goes away, how to stabilize it and make it part of better surge protection -- and at what cost.


After assessing all stressors affecting the land bridge they found "the threat of relative sea-level rise (or RSLR, which includes subsidence) was identified as the most critical: If conservative trajectories for RSLR projections were followed, most of the East Land Bridge could be fully submerged by 2060." The projections used in the report show relative sea-level rise at the land bridge to be at least 2.8 feet by the end of the century, and the engineers stressed, "The whole region delineated in this project is highly vulnerable to even relatively small permanent variations in the relative MSL (mean sea level)."

Unfortunately, since this report was compiled, research based on actual measurements shows the seas have been rising about 60 percent faster than those original projections made in 2007 by the International Panel on Climate Change.

The impact of sea level rise on any storm protection strategy was a constant theme in the report. The Gerwick team used a series of powerful slides to illustrate the fate of the land bridge as global warming powered by human-produced greenhouse gases continues to cause seas to rise. At just 2 feet of rise, the bridge was basically gone.


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Reply What global warming and rising sea levels mean for New Orleans (Original post)
Redfairen Jan 2013 OP
immoderate Jan 2013 #1
AverageJoe90 Jan 2013 #2
Uncle Joe Jan 2013 #3
MountainLaurel Jan 2013 #4

Response to Redfairen (Original post)

Sun Jan 13, 2013, 04:33 PM

1. From the article...


I studied the faces of the authority members as they viewed the slides. No one was laughing. They had questions -- but not about the science the engineers used. No one claimed the projections were based on a hoax or created by liberal scientists out to pad research grants. No one shouted "You lie!" No member said he disagreed with the peer-reviewed science on global warming supported by 97 percent of the world's accredited climatologists.

I have a friend who has made all these accusations. He rationalizes, deflects, and equivocates in defense when he's debunked.


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Response to immoderate (Reply #1)

Sun Jan 13, 2013, 11:20 PM

2. Indeed so.


The sad truth is, old New Orleans may indeed be lost to time someday, maybe as soon as this next century, perhaps.

3 feet may not sound like much to some folks, but for places like the Big Easy, or Key West, Tuvalu, or the Maldives, it makes all the difference in the world. And nobody knows just how much farther the ice will melt before it stops altogether.....

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Response to Redfairen (Original post)

Mon Jan 14, 2013, 02:10 AM

3. Kicked and recommended.

Thanks for the thread, Redfairen.

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Response to Redfairen (Original post)

Wed Jan 16, 2013, 01:41 PM

4. "If conservative trajectories for RSLR projections . . ."

Those conservative trajectories are being blown out of the water, so it looks like NO will be an island long before 2060.

Does anyone know to what extent the "rise" numbers also take into account subsequent sinking of the land?

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