BAD TIDINGS: La Jolla flooding circa 2070
When La Jolla Shores dedicated a street to Scripps Institution of Oceanography legend Walter Munk in October, Munk thanked the crowd but noted that, in 100 years, “Walter Munk Way will probably be underwater.”
A hundred years is a long time for people who have debt, businesses and other more pressing issues to worry about right now. So we wondered how La Jolla might look in 50 years instead.
“That 50 years has a big uncertainty to it, a range,” said Mark Merrifield, UC San Diego’s director of the Center for Climate Change Impacts & Adaptation. “Sea level could rise two feet in that time, some think it could be higher. And when you start talking about two feet, then things really change.” (Scripps scientists estimate that the sea level in La Jolla is a foot higher now than it was 100 years ago — an increase that is accelerating due to melting glaciers and the thermal expansion of seawater due to human-induced climate change.)
Even knowing how high the ocean will rise for sure wouldn’t tell you how much worse that rise will make flooding during high tides and storms. According to Climate Central, an independent organization of scientists and journalists researching and reporting climate change, “floods topping 3 feet above the high-tide line should be an annual occurrence by around 2070.”
In other words, the Pacific Ocean will regularly enter low-lying areas where it has only flooded once or twice before in recorded history. “Every spot that’s of concern now is bound to get a little worse,” Merrifield said.
The Cove and other sections of La Jolla’s infrastructure that are solidly above sea level will probably be spared from flooding in 50 years. However, for La Jolla Shores and other low-lying regions, the clock is ticking down to annual disasters during which any combination of high tides and a storm will threaten lives, houses and other structures.
“This has been a topic of discussion for our board and family,” said William J. Kellogg, owner of the La Jolla Beach & Tennis Club and the adjoining Marine Room, which tempts fate by marketing a “high-tide breakfast” during which diners watch waves crash against its windows — windows that had to be reinforced with bulletproof glass to resist the pressure.
“It is not clear at all that there is much we can actually do to make us immune from a rise in sea level,” Kellogg said. “We have learned how to cope with high tides over the years. You will note that the rooms at the north end of the club (the newest rooms) were elevated above the esplanade by several feet and moved inland as well. We have also perfected our sandbagging and waterproofing efforts over the years, so we are generally able to prevent damage to our rooms at times of high tides.
“I suspect we will have to continue these efforts and perhaps improve them as time goes on.”
Impacts from El Niño storms
Currently, the biggest flood threat to La Jolla occurs during El Niño events like the one in 2015-16 that knocked out the top portion of the stairs leading down to Horseshoe Beach. So will global warming increase the frequency or intensity of El Niño storms? “It’s difficult to tease out whether a particular event is due to some slow change or not,” said Scripps professor emeritus Bob Guza. “Our history here is short. So we don’t have good data on what’s due to climate change or random fluctuations. There’s always been warm summers. Now there’s six in a row. It’s possible that it’s not climate change, but it’s not likely.”
Ironically, what probably endangers La Jolla’s beaches the most are the human efforts to protect against global warming and sea-level rise.
“All the beaches in San Diego are subject to a chronic sand shortage caused by damning the rivers and protecting the cliffs,” Guza said. “They only get half as much now because of flood control.” And when there’s less sand at the shore, the ocean comes further in.
Recently, the California Coastal Commission required all coastal cities in the state to devise a plan addressing sea-level rise. Beach nourishment and sand replenishment will obviously be favored by the cities. But the Coastal Commission is also pushing one called “managed retreat,” in which all houses and other structures threatened by coastal erosion are removed and the beach is allowed to assume whatever its new natural state will be.
“The beaches are the best defense against storm waves,” Merrifield said. “And the stability of the beaches themselves starts to become troublesome. At what point does the water get too high for a beach to remain where it is?”
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