October 31, 2018
Los Angeles derives much of its charm from its diversity, both of its people and its amenities—rolling hills here, lovely architecture there, a national forest to the north and legendary beaches to the west. But much of it is in trouble: Sea level rise is coming for Los Angeles County and its 74 miles of coast.
According to a new report from the New York Academy of Sciences, it’ll take LA as much as $6.4 billion to fortify itself against an impending increase in coastal flooding, with moves such as nourishing its beaches with extra sand and elevating its ports. The tricky thing about sea level rise, however, is the uncertainty. Climate models are getting better at predicting how high seas will rise and how quickly, but no model can deliver guarantees. Maybe sea levels will rise by a foot by 2050. Or the water might end up rising 7 feet, but not for another 200 years.
“The key threat is actually the acceleration,” says climate scientist Jeroen C.J.H. Aerts of Vrije Universiteit Amsterdam, coauthor of the study. If sea level rise accelerates, infrastructure improvements might not be able to keep up, especially considering the magnitude of the engineering required to, say, raise the elevation of a whole port.
One scenario is that the neighboring ports of Los Angeles and Long Beach will get knocked offline by storm surges from future nasty weather events—and could eventually stop functioning completely if waters rise high enough. Together, these ports handle half of the containers coming into the United States, infusing the California economy with more than $60 billion a year and the national economy with $230 billion. Losing them to sea level rise would have staggering economic effects, so the only option is to adapt.
“If the port is one day or two days out of business, that means that trains cannot run in the direction of Utah or Nevada,” says Aerts. “And it means all other businesses that rely on the port are out of business as well.” We’re talking about a hit of a billion dollars each day the ports are out of commission.
But how do you fight back against a force like the sea? “What we suggested for the Port of LA and Long Beach is actually that they expand the ports toward the sea and raise those new facilities to anticipate future sea level rise,” says Aerts. You could then turn the old port facilities into a residential area, which would itself be lifted to stay dry.
Then there’s the matter of people. Think of Malibu and you think of rich people, who may well have the money to pay for seawalls or to retrofit their homes. But many lower-income folk also live near LA County’s 74 miles of coastline, and their homes may one day be in danger of inundation as well.
Coastal businesses, too, are likely suffer. California’s legendary beaches rake in $40 billion a year up and down the state. But here there’s actually a proven way to fight back: beach nourishment. The idea is to supplement eroded beaches with sand dredged offshore to keep them from washing out to sea. It’s a constant battle, as you have to keep adding sand that then gets washed away, but nourishment works to maintain the bulwark that is a healthy beach. That keeps infrastructure and homes safe from the ravages of the sea.
The problem in Southern California, though, is that engineers have already dammed the rivers, cutting off a major source of sand, which typically gets washed out to sea, thus replenishing coastlines. A workaround is to dredge harbors and other places where sand tends to build up and relocate it to a beach, replicating the natural process of rivers depositing new sediment on beaches.
Engineers are also getting better at figuring out exactly where to focus their efforts as sea levels rise. Researchers, for instance, build models of how waves will look in a particular area. “From comparing the model to how it performed over the historical data, we can sort of get a sense of is this model performing in a realistic manner,” says Sean Vitousek, an engineer at the University of Illinois at Chicago. “And then we can use various projections in terms of sea level rise and wave heights going forward to sort of extrapolate where the shoreline might be over a long period of time.”
These sorts of models will be essential tools to sustain the many ports, wastewater treatment facilities, world-class beaches, and other necessities that all hug the coasts. “The best solution would probably be to get the heck out of the way,” says Vitousek. “But with all the infrastructure in place and all the money involved in this, I don’t see that ever happening.” (Up in San Francisco, a massive campaign, which includes beach nourishment, is underway to save a new wastewater treatment plant from marine destruction.)
What works in LA, however, might not do as much good elsewhere. Miami, for example, is built on limestone that’s susceptible to groundwater flooding. Yet as LA experiments with self-defense, other cities are bound to take note. “My advice is be flexible,” says Aerts, coauthor of the new report. “That means if you want to protect a port, raise it and build your facilities such that it is still possible to raise it in the future. That’s the key, I think, for adapting to sea level rise, because we simply do not know exactly how big sea level rise will be in the future and when the acceleration takes place.”
The oceanic reckoning is coming for coastal communities. But by closely watching what cities like Los Angeles and nations like the Netherlands do to save themselves, the rest of the world might learn a thing or two about keeping our heads (and ports) above water.
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