Right now, an entire region of the United States is crumbling and sinking into the sea. Scientists say it's causing one of the worst and least-publicized environmental disasters in America's history. As Daniel Zwerdling reports for NPR News and American Radio Works, there's a moral to this story: when humans try to outwit nature, it can strike back with a vengeance.

The Greatest Wetlands on Earth
It's hard to sense how vast this problem is, until you see it from the air. A group of government officials has just buckled up their life jackets, because they're going to see the crisis first-hand.

One official has just flown in from the Pentagon, a few come from the state capital of Louisiana. And now this bright yellow helicopter lifts off the banks of the Mississippi River, and it heads toward a landscape that's vanishing. A biologist named Bill Good is guiding this inspection; he works with the state's department of natural resources. He says every couple of years, Louisiana loses a chunk of land that's bigger than Manhattan.

"And," Good notes, "if a foreign country came in and took that much of our real estate every year, that would be grounds for war."

The helicopter heads south along the muddy Mississippi. We skirt the skyline of New Orleans. We buzz over oil refineries and shipyards and freighters loaded with grain. Suddenly, civilization seems to come to an end.

We're flying over Louisiana's wetlands. Coastal wetlands are lands that gets flooded by tides. They're bursting with life, like rainforests , and these are some of the greatest wetlands on Earth. They sprawl 300 miles along the Gulf of Mexico, and they go up to 50 miles inland. They're the heart of the Mississippi Delta; and this astonishing landscape is vanishing. Good says if we'd taken this helicopter trip 50 years ago, it would have looked like the Great Plains.

"Exactly. It would look just like the prairies in the Midwest," says Good. "They were very solid, vast expanses of grass, of beautiful area, of verdant green from horizon to horizon."

A Tragedy of Immense Proportions
But now, we're looking at a ragged patchwork. There are thousands of streams and lakes and canals: they're eating away at the grasslands like cancer.

Bill Good nods his head toward the window, "Look down there, see those fishing boats in that bay?" When he flew over this spot the first time, back in the 1980s, that "bay" was solid ground. Satellite images show that every day, a chunk of land the size of a football field crumbles and turns into water.

"That scale is monumental and the significance is really hard to put into words," says Good.

That's why the government officials are inspecting the coast from the helicopter on this day, They say if the country doesn't do something dramatic to save this region, it could hurt the American economy. Bill Good says it would cripple the state.

"It's very hard to get your mind wrapped around how large and important and productive and unique all of this is," says Good. "To see it simply dying is a tragedy. A tragedy of immense proportions."

It took nature thousands of years to create these wetlands. If you want to understand how Americans are destroying them, it helps to get back on Earth.

A hugely successful disaster
Oliver Houck runs the environment program at Tulane University's Law School, and on a recent evening, he leads the way to one of the spots that helped trigger the wetlands crisis in the first place.

"Well, we're on the banks of the Mississippi River and these are the levees we're about to cross ... .it's a monster system."

To get there, we park near some old wooden houses next to the railroad tracks in New Orleans, and we scramble up the grassy embankment that looks over the river.

"The banks here are about 20 feet high," explains Houck, "and when we cross the banks, you'll see on the other side [that] if these levees were not here, that water would be at about eaves' level across the houses behind us."

I always wondered what "levees" meant. A levee is a wall. A levee is a wall to keep the river out of your living room.

Houck says before people built these walls, the giant Mississippi helped build America. Every day, the river and its tributaries washed millions of pounds of soil from all over the country down to the Gulf of Mexico.

"You can imagine what it would take in dump trucks to bring half a million tons of silt to south Louisiana," says Houck. "Well, it would take about two hundred thousand, two-and-half ton dump trucks every day, driving from Minnesota, from Rapid City, from Pittsburgh, from Denver. And in so doing, it brings down these enormous, enormous loads of earth to the mouth of the Mississippi."

Every year or so, Houck says, it would rain so much that the river would gush out of its banks, and all that mud and goo would spread out along the coast.

"And that's what built south Louisiana," Houck says. "The Mississippi built five million acres of land. A huge amount of land was wetland."

But when French settlers showed up in the 1700s, they tried to stop the Mississippi from flooding: they started building these walls. Eventually, the U.S. Army took over the job, and every time they thought they'd conquered nature, the river proved them wrong. So the army built more walls and they built them higher, they've built two thousand miles of levees as of today along the Mississippi River and its branches. And Houck says, the army has finally won the war—they've tamed the Mississippi.

"And so," describes Houck, "the project was—from an engineering point of view— brilliant, brilliant. It was hugely successful. From an environmental standpoint, it was a disaster."

Dying Wetlands

Now scientists like Denise Reed are trying to figure out how that disaster is changing the state.

"Okay, let's get it started," says Reed, "We'll start the engine. OK, we're gonna take that line off first—off last."

We've just left the dock in a scruffy town called Cocodrie, right in the heart of the wetlands. Reed moved here from England, so she could study them, for the University of New Orleans. She steers the boat down a bayou—that's the Cajun word for a slow stream— and it looks like we're floating through fields of grass. White pelicans swoop over our heads, and we pass fishing boats draped in nets.

"This marsh that we're gonna look at now," explains Reed. "It's pretty typical of many, many acres, thousands of acres of marsh in southern Louisiana. It's really hanging on the edge."

Reed says here's one reason why: After the Mississippi River built these wetlands, thousands of years ago, this whole region began to subside. And it is still is: all that rich heavy soil that the river used to dump here keeps compressing under its own weight. But that was never a problem in the old days, because the river would keep flooding and dumping more soil on the wetlands, and that would build them right back up.

"So," continues Reed, "when we built the levees along the Mississippi River, that cut off a supply of fresh water and sediment to these marshes that they would have gotten every three to five years—when a big flood came down the river. And so what that means is that the land is sinking."

The wetlands are literally sinking into the sea: the Gulf of Mexico is essentially drowning them. The moment we get out of the boat, we can feel that this wetland is dying.

Reed says if this were a healthy marsh, we'd be able to walk through the grasses like it was a hayfield. But every time we take a step, we sink up to our calves in water.

"I don't know how many times you fell in over your knees, but I fell in several times. It's full of holes," describes Reed.

Now, if I were just here on my own, sloshing around in this water that we keep falling in, I'd think, "Oh, marsh! That's what it's supposed to be, land and water together. So why is this a sign that this marsh is dying?"

"Well, " explains Reed, "what it tells us is that there's not much holding it together, apart from the plant roots. There's nothing very firm down there. It's not anchored very well.

"That's bad! And of course we're standing here, right next to a pond. This is not a very big one. When you fly over Louisiana, you can see that there are myriads of ponds this size, and very, very much bigger. But what seems to have happened here is that the plants that were there have said, 'I give up.' The plants die, and when plants die, there's nothing to hold it together, and what you end up with is a pond like this. And that's land loss! This is what coastal land loss is in Louisiana. Something that's a marsh with grass—turning to open water.

And Reed says, there's another reason these wetlands are sick. She says look back at that waterway we just came down, to get into this marsh—notice how straight it is? Nature didn't build lines like that— the energy industry did. In the middle of the 1900s, companies like Shell and Texaco found huge amounts of energy below the wetlands.

"This is the kind of canal that the companies had to dredge through the marsh to actually drill holes to extract oil and gas," says Reed. "There are thousands and thousands and thousands of these across coastal Louisiana."

In fact, when you wind through the wetlands in a boat, you start to think, 'This is wilderness'—the landscape is hauntingly beautiful. Then, suddenly, there's a cluster of drilling rigs like a grove of metal trees. That's made energy the biggest industry in Louisiana, but the wetlands are dying much faster where these canals have carved them up.

"This marsh cannot survive in this state much longer. It's like the edge of a blanket starting to fray. Once it starts, it goes very rapidly," warns Reed.

Satellite photos suggest that if the wetlands keep disappearing, the entire nation could be affected. Americans eat more shrimp and crabs and other seafood from Louisiana than from any state except Alaska; the creatures spend part of their lives in these wetlands. You buy more oil and gas from Louisiana and the Gulf of Mexico than from almost any other state—and a lot of that fuel flows through pipelines under these wetlands. So, researchers say that as the wetlands vanish, some kinds of seafood might disappear, and you'll have to pay more money to drive your car and heat your home.

Sinking Louisiana towns
Here in Louisiana, people's lives are already changing.

In the cemetery, in the town of Leeville, Rick Eddy runs the bait and tackle shop. He's taking us out on his boat to show us where the townspeople are buried, because this is the only way you can see it.

"OK, see over here—here's one of the headstones sticking up out of the water," points out Eddy. "The tides a little high right now, but usually you can see anywhere from 25 to 30 headstones.

"It's definitely all under water," continues Eddy. "The cemetery's all under water. It's eroded right away. I've been in this area for 15 years. When I first came into this area, there was all land there. It's very heartbreaking. And to have something like this come along—and erosion. Some of the headstones are all busted up. The mausoleums, it's just a pile of rubble really. Kinda hard to put it in words. "