“Water’s coming up, watch your feet, folks! Things are getting exciting,” Lori Lambertson, a science educator with the Exploratorium, tells the 50 or so people who gather around her Saturday on the waterfront promenade between San Francisco’s Pier 3 and Pier 5.
Lambertson is standing on a bench, her back to the bay, explaining to the crowd how tides work. Behind her, the water laps, then sloshes, then flows over the seawall and onto the sidewalk, scattering the crowd.
People shriek in excitement and surprise, scrambling to keep their shoes dry.
It’s 10:24 a.m. on December 4, a few minutes before high tide. But this is no ordinary rise. It’s a Perigean spring tide, colloquially known as a king tide, the highest high of the year.
Within moments, it will peak above seven feet; a week from now, high tide will be nearly two feet lower. (If you missed them, a second set of king tides are due to arrive on New Year’s Day.)
This is more than an annual display of the ocean’s might. “It’s not just, ‘Ooh, ahh! The king tides! We got wet!’” Lambertson tells the crowd. “Our king tides are the high tides of tomorrow because of sea level rise.”
A mighty strong pull
Tides are caused by the gravitational force that both the Sun and the moon exert on Earth. How high or low they get depends on the three celestial bodies’ alignment and distance from one another.
During king tides, which hit our shores this past weekend and will return the first three days of January, the moon is closest to our planet in its 27-day elliptical orbit, and Earth is closest to the Sun in its annual elliptical orbit, and all three are in line with each other, exerting a greater gravitational force.
Add to the king tide any sort of swell, wind, or storm surge, and dramatic waves will send water pouring over seawalls and scatter sand, rocks, and other debris on roads and other open spaces.
During Saturday’s king tide walk, all that was needed to send the bay onto the Embarcadero was the swell from a passing ship. “It’s kind of exciting to see the water come up over the sidewalk where it shouldn’t be,” Lambertson says. “But when this starts to happen more and more frequently it’s not just going to be a nuisance. It’s really dangerous and there are a lot of problems associated with it. This is really a look into our future.”
Flooding ahead
The most recent state projections, released in 2018, predict that California will face between 0.9 and 2.7 feet of sea level rise by 2050. It’s not hyperbole to call the king tides a “preview”; where the water was this weekend will be an everyday occurrence some 30 years from now.
Baykeeper, an environmental nonprofit, estimates that one foot of sea level rise accompanied by a 100-year storm — a storm that has a 1 percent chance of occurring in any year — would cause $45 billion in damage to Bay Area homes and businesses.
One solution that’s not likely to be on the table is a massive tidal barrier at the Golden Gate, in the style of the Thames Barrier in London or Venice, Italy’s MOSE barrier. The idea has cropped up time and again since the early aughts (San Jose mayor Sam Liccardo revived it this summer), but each time it’s been dismissed as too expensive, complicated, and detrimental to the Bay’s sensitive species and delicate habitats.
A new wave of climate scholars, urban planners, and, in rare cases, elected officials are pushing for a different response to rising seas: Move away from them. The strategy, most commonly called managed retreat, involves relocating at-risk buildings and infrastructure before they’re damaged by flooding.
It’s already in the works on a small scale in the greater Bay Area. In the Sonoma County hamlet of Gleason Beach, Caltrans is moving a crumbling stretch of Highway 1 inland. In Marin, Stinson Beach has acknowledged it needs to plan for retreat. In dense and housing-starved San Francisco, retreat is more problematic; the city’s 2016 sea level rise action plan states that it could be “expected along less developed shorelines… or when other options have been exhausted.”
Instead, San Francisco is doubling down on building up its Bay shoreline with massive developments like Mission Rock, Pier 70, the Potrero Power Station, Treasure Island, and eventually the Hunters Point Shipyard.
A higher waterfront
What exactly to do about rising seas is the million-dollar question. Scratch that. It’s the billions-and-billions-of-dollars question.
A memorandum released by the Port of SF in November warned that if we do nothing, “we could see up to $30 billion in present value damage by 2100 for the Embarcadero Seawall area of the waterfront,” which runs three miles from Fisherman’s Wharf to Mission Creek. It added that the Embarcadero would have to be raised by “2 to 7 feet or more” to protect downtown from future flooding.
The memo didn’t put a price tag on this, but the Port’s website states that seawall improvements will cost $5 billion. A small portion of that work, which is in early planning stages, will be funded by the $425 million raised through bonds approved by city voters in 2018.
The port and U.S. Army Corps of Engineers are also studying a larger swathe of the waterfront from Fisherman’s Wharf to Islais Creek to pinpoint where we’ll be vulnerable to rising waters and propose solutions. No results have yet been released.
“We don’t want to build a fence,” says Matt Wickens, an engineer with the port, who addressed the crowd Saturday with Lambertson. The port is looking for an “elegant” solution that still manages to “capture the whole shoreline” and doesn’t create “outflanking” — inadvertently pushing rising waters away from, say, the Embarcadero, and into unprotected neighborhoods nearby. (Wickens acknowledged in a follow-up email that managed retreat might need to be part of the city’s long-term strategy.)
With one foot of sea level rise and a 100-year storm, 13,500 people, 58 percent of whom are people of color, will face significant flood risks. The area where Market Street and the Embarcadero meet “will be significantly inundated.” The commutes of 360,000 people will be disrupted. Thousands of homes and businesses, more than 40 miles of roads, and more than 25 miles of Muni and cable car tracks will be affected. And that’s just in the bayfront sliver of land where the port has jurisdiction.
Rising seas will carry other hazards, as a recent study from UCLA’s Fielding School of Public Health showed. By 2100, more than 400 hazardous sites across California are expected to flood at least once a year. A handful of them — including sewage treatment plants, industrial facilities, and the Hunters Point Naval Shipyard superfund site — are located in San Francisco.
“This is also an environmental justice issue because many communities who live near these areas are communities of color,” the Exploratorium’s Lambertson says. “So we need to make sure that we build a resilient climate future together.”
Take a picture
“Together” is a key word for scientists and educators like Lambertson, who are encouraging people to get out and document king tides around the world. Photos are uploaded into online databases and help researchers, planners, and others build more accurate climate models. For instance, the Our Coast Our Future model shows that on a calm day with 1.6 feet of sea level rise, the sidewalk between Piers 3 and 5 would be partially inundated.
Sure enough, with Saturday’s calm conditions and a tide that’s 1.7 feet higher than it will be several days in the future, water is lapping onto the sidewalk.
The photos can also serve as wake-up calls. “In 2009, when the project began, a lot of people in the coastal science and management community were trying to figure out how to better communicate climate change risks to the general public,” says Marina Psaros, a co-founder of the California King Tides Project, and author of The Atlas of Disappearing Places: Our Coasts and Oceans in the Climate Crisis.
“When you see that beach that’s flooded, or the wetland, or the trail, or the road that’s underwater, or the house, or the infrastructure that’s really close to the water, picturing the water at least that high every day is powerful,” says Annie Kohut Frankel, manager of the California King Tides Project at the California Coastal Commission. “It makes you want to do something.”
