An aerial view of Seaside Heights, New Jersey, almost a month since the area was hit by Hurricane Sandy in Oct. 2012. A new study says that while two-thirds of U.S. coastlines have some kind of natural barrier against extreme weather and rising sea levels, 1.3 million Americans still live in “high-risk” zones. (Photo: Reuters)

Natural barriers like reefs and sand dunes protect 67 percent, or two-thirds, of the U.S. coastline from extreme weather and rising sea levels, according to a new study from scientists at Stanford University. Researchers at the university in California created the first complete map of U.S. shoreline ecosystems and identified where natural features protect us against climate change.

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"The natural environment plays a key role in protecting our nation's coasts," Katie Arkema, lead author of the study and a Stanford University scientist who worked on the project, said in a press release. "If we lose these defenses, we will either have to have massive investments in engineered defenses or risk greater damage to millions of people and billions in property."

USA Today reports that the Stanford scientists came up with a coastal hazard index, based on the presence or absence of natural habitats, human population, property values, erosion and five scenarios for climate change-induced sea level rise. They found that two-thirds of U.S. shorelines have some kind of protective natural barrier like a reef, dunes, mangroves or sea grasses, which help keep ocean water at bay.

Still, 1.3 million Americans, including hundreds of thousands of poor and elderly, live in "high-risk" zones along the shoreline, where they are vulnerable to the elements. These areas, encompassing 16 percent of the U.S. coastline, represent $300 billion in residential property. Additionally, the study found that 90 years from now, the amount of highly threatened people and property will increase by 30 to 60 percent as sea levels continue to rise.  

Researchers found that the East and Gulf Coast are more vulnerable to sea level rise than the West Coast. The most heavily barricaded coastlines are those along California, New York and Florida.

The devastating effects of climate change were witnessed in late 2012 when Superstorm Sandy bombarded the eastern seaboard and caused $65 billion in damages. Mitigating the effects of climate change on U.S. coastal towns and cities will have to involve preserving natural ecosystems more so than building expensive manmade barriers.  

"Hardening our shorelines with sea walls and other costly engineering shouldn't be the default solution," Peter Kareiva, co-author of the study and chief scientist at The Nature Conservancy, said. "This study helps us identify those places and opportunities we have to keep nature protecting our coastal communities -- and giving us all the other benefits it can provide, such as recreation, fish nurseries, water filtration and erosion control."

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