Researcher Jay Combe has reached a troubling conclusion. He's told his supervisors at the Army Corps of Engineers that if The Hurricane hits New Orleans, most of the buildings in the city would probably be destroyed. If the water didn't demolish them, the hurricane's horrific winds would. And Combe says that raises a question: How many people would die?

Some researchers say 40,000. Some say 20,000. This Army Corps researcher says those figures are probably too low.

Combe worries, "I think of a terrible disaster. I think of 100,000."

Do you dream sometimes about a hurricane?

"It's strange you should ask that," answers Combe. "I had a dream the other night about flooding, and it's unusual because I don't usually have bad dreams. I can't really remember the dream except that water was coming down a slope. I don't remember much of it, fortunately. I don't want to remember."

Federal officials are so stunned by these sorts of findings that they're rethinking their assumptions about New Orleans. Officials in the U.S. Army say, 'There's got to be a way to prevent some of that devastation.' So they'll study whether they should build more levees and build them higher. They'll study whether the region needs new highways, so people can evacuate faster.

Critics say, 'We don't need more construction, we need less.'

Oliver Houck from Tulane University. Photo: William Brangham/NOW with Bill Moyers

Oliver Houck from Tulane University says, "Stop the foolishness of permitting yet more residential development. We are granting permits every week for new subdivisions right in the path of where this stuff is going to go. We're still covering those people with flood insurance, Daniel."

And state and federal officials are asking Congress to launch a massive project to restore the region's natural defenses. They want billions of dollars to try to rebuild some of the crumbling wetlands, which buffer New Orleans from hurricanes raging up from the Gulf. Scientists say that's the best way to save the city: make that ancient shield of wetlands strong again.

But even if the country started those projects tomorrow, it would take decades to see results. Scientists like Joe Suhayda say they can't wait that long to protect New Orleans. So he's pushing a stopgap idea. Some people say it's sort of nutty.

"It's a lifeboat," explains Suhayda. "And the lifeboat is there because it anticipates, at some point, possibly, the main ship is going to sink."

Some scientists believe that if a huge storm hits New Orleans, the city would have to be abandoned. Bulldoze the rubble, rebuild someplace else. But Suhayda thinks they could save a piece of it. He wants the nation to build a massive wall around the downtown heart of New Orleans. It would be like the giant walls that protected medieval cities. It'd be almost three stories high, and miles around. It would enclose the French Quarter and government buildings, and a hospital and housing. If a monster hurricane comes, at least that part of the city could survive. Suhayda calls it 'the community haven.' He shows me a small example.

Joe Suhayda wants the nation to build a massive wall around the downtown heart of New Orleans. Photo: William Brangham/NOW with Bill Moyers

"What we're on now is a concrete wall that is of the type that I was suggesting as a community haven," explains Suhayda.

This one's about 20 feet high, with grassy slopes. It shields the nearby houses from the lake, sort of like a gated community. There's a pair of huge solid-steel gates—like a bank vault—at the entrance to the neighborhood.

"So," says Suhayda, "we would have a wall of this type, maybe a little bit higher, that would enclose the community haven. "

Suhayda pictures the scenario unfolding like a disaster movie: the forecast comes in, a giant hurricane's approaching, and government officials sound the alarm: 'Get to the haven, if you can.'

"And so through gates like this, people would come in buses, walking or automobiles and get behind the wall," describes Suhayda.

Is there a siren saying, 'Everybody get inside the gate! Two minutes left! One minute left! '?

"You're exactly right," says Suhayda. "It would come down to a critical last few minutes. I can imagine people trying to carry their dogs and their prized possessions and fighting winds, that at this point would be very very strong. Some people probably falling down and needing help and maybe there'd be crews that would actually go out and try to assist these people. But there'd come a time when a decision would have to be made to stop any entrance to the haven."