New Orleans — Louisiana's coast is under threat as a quarter of the state's wetlands, an area about the size of Delaware, have disappeared in the last 100 years, according to the U.S. Geological Survey .

The wetlands are a critical buffer that shield Louisiana communities from monster hurricanes .

While massive flood walls and human-made marshes are helpful, coastal scientist Alisha Renfro and campaign director Simone Maloz with the nonprofit group Restore the Mississippi River Delta say say those projects alone are not enough to rebuild and counteract future projected land loss.

"You can reduce storm surge up to a foot with just a mile of coastal wetlands," Renfro told CBS News.

"A tough lesson that we learned after Katrina: we have to think long term. We also have to thin

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