U.S. coastal communities could begin to experience 100-year floods on an annual basis by 2050 due to rising sea levels caused by climate change, according to national climate change expert Michael Oppenheimer, who delivered the keynote address today at the Center for Planning Excellence’s virtual Smart Growth Summit.
For vulnerable south Louisiana, the picture of the decades to come is particularly grim: Temperatures will get hotter, crops yields will decrease, and storms and hurricanes will become more intense, as the Gulf of Mexico continues to eat away at the state’s eroding coastline.
“What you’re particularly going to have trouble with down there are the lower-lying coastal areas like Grand Isle,” says Oppenheimer, a Princeton University researcher and author of the International Panel on Climate Change’s Assessment Report. “The 10-year flooding events in those communities will be happening three times a year by 2050 and by 2100, you’ll be having them every time there’s a high tide. You won’t have to wait for a storm.”
Oppenheimer’s admittedly downbeat assessment was intended to help land-use planners and designers think about how to prepare and build for a not-too-distant future that is going to be in constant flux and will look very different than it does today.
Though reducing greenhouse gas emissions even by a modest amount will help mitigate the problems in the long term, in the short term, it’s too late to reverse the trajectory.
“We are more or less stuck with CO2 we are putting into the atmosphere, unless we figure out a way to suck it out of the air,” he says.
Planners in Louisiana have four options to deal with the climate crisis. Hard protection, like seawalls and levees; ecosystem-based solutions, like wetlands enhancement; accommodations—raising houses and, even, building new land out into the water; and relocation.
Infrastructure solutions like seawalls and levees are effective, but they’re also expensive and it’s impossible to protect every inch of U.S. coastline with a levee.
“So you’ll be competing with other U.S. areas for federal dollars,” he says.
Wetland enhancements are less expensive but long term, it’s unclear how effective they are. Raising houses is a good short-term solution, but it doesn’t do any good once sea levels rise beyond a certain point. Relocation, therefore, is going to be the most likely solution.
“Unfortunately, you’re not going to be able to protect everything, so there is going to be a lot of relocation,” he says. “But it’s not the kind of thing you want to do on an emergency basis.”
Also troubling, Oppenheimer says, are the equity issues baked into the problem: Those with the highest exposure and risk are often the ones with the fewest resources and ability to respond to the challenges.
“It’s a situation rife for high inequity,” he says.
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