Nature protects coasts

Posted by Christine, October 14, 2013

Surging storms and rising seas threaten millions of U.S. residents and billions of dollars in property along coastlines. The nation’s strongest defense, according to a new study by scientists with the Natural Capital Project at the Stanford Woods Institute for the Environment, comes from natural coastal habitats.

Of the 25 most densely populated counties in the United States, 23 of them are along the coastline. The study, “Coastal habitats shield people and property from sea-level rise and storms” published in Nature Climate Change, mapped the entire U.S. coastline and reports that habitats such as sea grasses, mangroves, sand dunes, and coral reefs currently protect two-thirds of the U.S. coastline, including at-risk areas such as New York and Florida.

“The natural environment plays a key role in protecting our nation’s coasts,” said study lead author Katie Arkema, a Woods postdoctoral scholar. “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.”

Damage to the town of Mantoloking, New Jersey after Hurricane Sandy.  Photo in the public domain.Damage to the town of Mantoloking, New Jersey after Hurricane Sandy. Photo in the public domain.

Although attempts at protecting coastal population centers have typically involved hardening shorelines with “gray technologies” such as cement sea walls, there are disadvantages to engineered solutions. Not only are they expensive to build and difficult to maintain, but they can reduce the natural beauty of an area, increase erosion, affect water quality, and deplete the number of marine creatures living in the region. In fact, many “gray” solutions may actually damage natural habitats that are already acting as protection for coastlines.

Conservation and restoration of shoreline marshes, seagrass beds, oyster beds, coral reefs, dunes, coastal forests, and large kelp forests offer natural defense mechanisms for coastlines, buffering them from waves and storm surges. Loss of these habitats would increase the vulnerability of human populations, with the economies of the eastern seaboard and the Gulf of Mexico expected to suffer the most damage.

“Hardening our shorelines with sea walls and other costly engineering shouldn’t be the default solution,” says Peter Kareiva, the chief scientist at The Nature Conservancy and co-author of the study. “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.”

Hurricane Sandy alone caused $68 billion in damage to the U.S. Soon, billions more will be spent on restoration of other areas affected by the storm along the Eastern Seaboard and the Gulf of Mexico. This study provides critical national and localized information for coastal planners who are considering where conservation and restoration efforts could have the biggest impacts.

“As a nation, we should be investing in nature to protect our coastal communities,” said Mary Ruckelshaus, managing director of the Natural Capital Project. “The number of people, poor families, elderly and total value of residential property that are most exposed to hazards can be reduced by half if existing coastal habitats remain fully intact.”

CITATION: Arkema, K. et al. Coastal habitats shield people and property from sea-level rise and storms. 2013. Nature Climate Change, 3, 913-918.

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