One of the ideas people have explored is building seawalls, coastal defenses that deflect rising water. The Army Corps of Engineers has one in the works for Galveston Bay, and it is proposing to build a 20-foot seawall near Virginia Key in Miami, which could get over 3½ feet of sea level rise by 2100, according to the new report.
But not everyone is onboard with seawalls as end-all solutions. “The region is working on a plan to potentially create this big giant coastal barrier,” says Stokes, the president of the Galveston Bay Foundation. “We’ve got significant questions about it—it’s not designed well, it’s going to take 20 years to construct, and it could be out of date by the time they finally finish it.”
Miami’s an even more complicated case, because it not only gets water coming in from the beach, but also from below, as seawater seeps through the porous rock the city’s built on. That would cut into the efficacy of a seawall.
And while seawalls hold water back from one area, it still has to go somewhere. Modeling of the San Francisco Bay, for example, where the idea is also controversial, shows that building a wall on one stretch of coastline would actually flood nearby communities. If a wealthy city builds a wall, it may just push storm water toward its poorer neighbors. “Erecting a giant concrete wall would, in some ways, significantly reduce property value, and in other ways protect people who already had more assets to be able to relocate or to cope with the impacts of sea level rise,” says Natalia Brown, the climate justice program manager at Catalyst Miami, an economic justice nonprofit, of the proposed Miami seawall.
Instead, Brown says, some Miami communities are exploring a hybrid approach: small seawalls to mitigate flooding combined with nature-based solutions, like bolstering wetlands or mangrove forests, which naturally absorb excess seawater. Vegetation could be combined with engineered boardwalks to create a seaside park—a kind of seawall that benefits a community instead of looming over it. “Planting some of the native species, and different types of mangroves in Florida, is a really popular intervention among community members,” says Brown. “They are a really, really excellent way to retain water and to mitigate storm surge.”
In Galveston Bay, Stokes’ group supports a similar idea: shoring up a natural wetland that would act as a sort of speed bump, absorbing storm surges. Engineers might bolster the area by building an underwater wall of rocks just off the shoreline. “It is designed to trip the waves before they hit your shoreline,” says Stokes. “The waves will fall over the top of the rock breakwater, and the sediment that’s in those waves will start to build up. You’re actually sort of naturally creating land, and that land will be marsh.” So instead of losing land to the sea, the city would be creating a habitat that fights sea level rise.
And if you don’t happen to live along the Gulf Coast, don’t think you also won’t get your feet wet. The report makes clear that sea level rise is a national problem that will flare up locally. “These impacts are going to be felt across the entirety of the US coastlines—in different ways, admittedly,” says Hamlington. “But they will be felt everywhere. So it’s important that this information is available to everyone.”
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