Hari Sreenivasan has our story.

　　WOMAN: I would like to introduce to John Barry.

　　MAN: Hi, John.

　　HARI SREENIVASAN: John Barry, the award-winning historian and writer, and a man who's normally holed up in a book-lined office by himself, has lately become one of the busiest men in Louisiana.

　　JOHN BARRY, Author, "Rising Tide": This is not just another piece of legislation.

　　HARI SREENIVASAN: He's been talking to rotary clubs.

　　JOHN BARRY: I'm John Barry.

　　HARI SREENIVASAN: Testifying before the state legislature.

　　JOHN BARRY: There is no debate, scientifically, over that fact.

　　HARI SREENIVASAN: Why? Barry is fighting a controversial legal and political battle to try and force the powerful oil and gas industry to pay billions for the role their dredging and drilling has played in the erosion of the coast of Louisiana.

　　Barry is best known for his book "Rising Tide," an account of the devastating 1927 flood in Louisiana. That bestseller made him something of a local celebrity, and has given him a platform to sound the alarm about the current land-loss crisis in the state.

　　JOHN BARRY: We have lost close to 2,000 square miles of land. That loss continues every minute. Towns are going to disappear. Cities, small cities are going to disappear. New Orleans itself is going to become almost too dangerous to live in.

　　HARI SREENIVASAN: Nearly everywhere you look in coastal Louisiana, the landscape is crumbling. In the town of Leeville 80 miles south of New Orleans, structures meant to last for generations are falling apart.

　　What was once dense farmland is now gone. The main road through town now dead-ends in the water. Even the local cemetery can't hold onto the ground around it.

　　BOBBY LYNN: What's happening is, it's like a cancer.

　　HARI SREENIVASAN: Fisherman and businessman Bobby Lynn has been here 25 years, and he's seen dramatic changes all around him.

　　BOBBY LYNN: You can see the little, bitty islands. Well, 20 years ago, that was just one solid piece of lush, fertile marsh, and now it's just little, bitty islands and very little island left now, because every year, we lose so much of it.

　　EUGENE TURNER, Louisiana State University: It's not like losing a few acres of beachfront property in Maryland or North Carolina. We're losing square miles a year.

　　HARI SREENIVASAN: Gene Turner, one of the preeminent coastal scientists in the region, says Louisiana's coast is disappearing for several reasons:

　　First, the levees and dams built along the Mississippi to stop floods also stop crucial dirt and sediment from replenishing the wetlands. Second, not only are sea levels rising, but these wetlands naturally sink down a bit every year, bringing in more saltwater and further damaging the marshes.

　　And, third, ever since oil was discovered here, energy companies have dredged an estimated 10,000 miles of canals through the wetlands to move their drilling rigs into place. These canals degrade the marshes on either side of their banks, further weakening the wetlands, so when a big hurricane like Katrina comes through, the wetlands are torn up even more.

　　Virtually every coastal scientist here says dredging these canals has been a major contributor to Louisiana's land loss.

　　EUGENE TURNER: Where there's a lot of dredging, there's a lot of land loss. Where there's a little bit of dredging, there's a little bit of land loss. Where there's no dredging, there's hardly any land loss. It's an inescapable conclusion.

　　HARI SREENIVASAN: These marshes are not only a valuable ecosystem for the entire Gulf, but for hundreds of years, this huge network of wetlands has defended the city of New Orleans from major storms.

　　I'm on a levee in New Orleans. These are the city's last line of defense. As the wetlands disappear along the coastline, it puts hundreds of thousands of homes here at greater risk from a catastrophic storm surge.

　　After Hurricane Katrina, John Barry was appointed to sit on a new regional flood protection authority board. Its job was to oversee and monitor the various flood protections being built in a part of metro New Orleans.

　　JOHN BARRY: We recognized that the danger was increasing.

　　HARI SREENIVASAN: Last July, alleging that the oil and gas industry's damage to the wetlands made flooding in the city more likely, the flood protection authority sued 97 oil and gas companies.

　　The suit argues the companies were negligent in how they operated in the wetlands, and it points to numerous permits requiring companies to repair and fill in the canals when they were done.

　　JOHN BARRY: They promised in the permits, which are negotiated like contracts, that they were going to do certain things. They broke their word. They didn't do them. The law requires them to do certain things. They didn't do them. They broke their word. And they certainly haven't taken responsibility for fixing the — for fixing these things.

　　GIFFORD BRIGGS, Louisiana Oil & Gas Association: This is about billions of dollars, billions of dollars that will be put on for attorneys' fees. It's not really about coastal restoration.

　　HARI SREENIVASAN: Gifford Briggs is the vice president for the Louisiana Oil and Gas Association, which represents all but the biggest oil companies like Exxon and BP. Briggs argues that the entire nation benefited from the cheap and abundant energy his industry pulls out of those wetlands.

　　So, does the industry say that it's not responsible at all for any of the wetland damage?

　　GIFFORD BRIGGS: There's no denying that canals were cut, and so — and potentially that there may be impacts from the creation of those canals. But those canals were created with the blessing of the state of Louisiana, with the blessing of those local governments, and in partnership with those, contributed millions and billions of dollars into the state and to local governments for the production of those natural resources.

　　HARI SREENIVASAN: Earlier this year, the industry tried to get the lawsuit thrown out in court, but a judge rejected their motion and allowed the suit to proceed. Most lawsuits are fought in court, but this case has attracted so much attention and opposition from the oil and gas industry, that the fight moved here, to the state capitol.

　　HARI SREENIVASAN: Governor Bobby Jindal, a strong defender of the industry, denounced the lawsuit, saying: "These trial lawyers are taking this action at the expense of our coast and thousands of hardworking Louisianians who help fuel America by working in the energy industry."

　　And in the hallways of the state capitol in Baton Rouge, lawmakers who support that industry have been crafting different bills to retroactively kill the lawsuit. A bill was introduced to limit which state agencies were allowed to bring lawsuits. Another bill changed how the flood control board was appointed. Another even challenged how that board hired its lawyers.

　　ROBERT ADLEY, R, Louisiana State Senator: We have, in my view, a rogue agency of the state of Louisiana benefiting trial attorneys, and not working together with the rest of the state to solve our problem.

　　HARI SREENIVASAN: State Senator Robert Adley, who used to run an oil and gas company and now consults for the industry, has sponsored the majority of the bills seeking to derail the suit. Adley argues that a local flood protection authority has no standing to sue an entire industry, especially when state and federal authorities permitted the industry to perform all that drilling.

　　ROBERT ADLEY: To intervene in permits that you were no party to, had nothing to do with, that's a violation of the law, in my opinion. You don't have standing to do that.

　　HARI SREENIVASAN: So — but why not just let a judge say, you don't have standing to do that? Why go through, I have heard anywhere from a half-dozen to 17 different pieces of legislation to try to stop a lawsuit? Why not just let a judge say, you don't have standing?

　　ROBERT ADLEY: Their job is clearly to interpret the law. Our job is to manage the state. We have that obligation. We shouldn't just abdicate our responsibility to the courts. The people I represent wouldn't like that very much, and, obviously, I don't think the state would like that very much.

　　JOHN BARRY: The real goal is not to go to court and spend 15 years before — before Exxon uses up all the appeals. The real goal is to get the people around a table, solve the problem for the state, and get money flowing and dedicated to fixing the coast.

　　HARI SREENIVASAN: Barry points out that Louisiana has spent just $2 billion on restoration since 2008. Four years later, the state drafted a $50 billion master plan for coastal restoration, but it is nowhere near fully funded. This is why, Barry says, the flood authority's lawsuit is a crucial lever.

　　JOHN BARRY: No amount of money is going to allow us to rebuild the 2,000 square miles that we have already lost. But we can save a lot of what is left. You can't do that for free, however.

　　HARI SREENIVASAN: The lawsuit suffered a blow when the state Senate passed a bill that would retroactively suspend the flood authority's ability to sue. That bill is expected to be voted on later this week.