Louisiana’s Governor Declares State Of Emergency Over Disappearing Coastline

It's the parts of the delta which are fed by the Old Mississippi which are disappearing, and this is a totally natural process. The same river is what serves the port of New Orleans. The natural course of the river can only be temporarily stayed; it will find a way around the ORCS eventually. If the river is allowed to flow naturally, the majority of Southeast Louisiana, including New Orleans and Lake Ponchartrain, will disappear under the ocean.

I don't think it's an either-or, though. The delta's generally pretty close to sea level (NOLA averages about 5ft below IIRC) as is, and when the seas rise, that means more Gulf and less Louisiana Delta. It'll just vanish quicker because we haven't been letting the river refresh the land for a few centuries.

Ultimately it becomes a question of how much money anyone is willing to dump into this; I wouldn't be that surprised to see the city I was born and raised in become either New Atlantis or New Venice in my lifetime.

How I wish that were true. Many problems of humanity are very predictable - climate change is an easy one, but probably we can all think of some problems in the tech industry - and yet people do it anyway. If it were true, we wouldn't fight any wars.

> If the coastline changes were significantly caused by climate change/rising sea levels then the other Gulf coast states would have problems too.

That's not how it works. There is a lot of coastline in the world and the effect of climate change varies greatly. Look at just the East Coast of the U.S.: Miami is facing big problems; New Jersey is seeing some problems; New York is not (yet). Holland, with its low-lying reclaimed land, is likely to face problems long before the cliffs of Dover.

Yes, exactly right. This is what the entire southern coast of Louisiana is.

Envision the river like a wiggling hose spewing out water and sediment. As the sediment piles up in one area, that eventually is no longer the easiest path to the Gulf, and the hose jigs off to one side, finding a better path. When it does, it leaves behind huge, flat, fertile floodplains, bayous, and marshes. Then the new course too eventually fills up and it picks a new course again, often one of the previous ones which is now relatively more appealing.

It's been doing that for thousands of years, wandering around the southern coast of Louisiana, piling up sediment that flowed south into the great bayous and swamps.

That was until the Mississippi River became a giant trade path and New Orleans its terminus. If the Mississippi were allowed to change course and allow most of its water to reach the Gulf by going through the Atchafalaya River, the ports of Baton Rouge and New Orleans would be left dry. Meanwhile, Morgan City would be washed into the Gulf.

To prevent that, the Army Corps of Engineers has, for decades built barriers along the sides of the Mississippi to force the water to stay in that channel. Those barriers in turn reduce friction and cause the River to flow faster and faster. That means that instead of building up sediment at the current end of the river, that stuff is getting washed farther out into the Gulf.

Meanwhile, the Atchafalaya Basin and other areas which would have gotten their "turn" and had their own deltas built up have been left to erode with little new sediment coming into them.

This has been a well-known problem for longer than most of us have been alive. In the early 90s, I did a science project as a kid on it. But New Orleans has never been known for its long term planning. ("Laissez les bon temps rouler.") See also: Hurricane Katrina, which was an infrastructure failure more than a weather disaster.

So here we are.

Prediction: The only intended goal of this measure is to suck more federal cash into Louisiana which will be used to line political pockets. No real substantive ecological or infrastructure changes will come of it.