A Rising Tide

Bob Battalio and David Revell brace against a powerful wind as bits of litter fly past and waves crash below. It’s a bright, clear April afternoon, and we are standing on the Pacifica pier, the long, L-shaped piece of engineering that juts defiantly into the ocean. Pacifica, located just a few miles south of San Francisco on Highway 1, is a town of about 40,000. It crops up periodically in the news due to its love-hate relationship
with the Pacific Ocean. Pacifica wants to stay where it is, but the ocean keeps grabbing at chunks of it.

One section of the town, along coastal Beach Boulevard, is bounded by a stretch of vertical seawall, intended to protect the buildings just behind it from the force of the Pacific. The wall itself is protected from the ocean by pile after pile of rocks and boulders, called riprap. This afternoon, the tide only reaches to the bottom of the wall, but Battalio points out that the ocean will at times overtop it, creating huge sprays of water that attract television news cameras from miles around. He also indicates smaller walls just inland of the seawall—erected, he says, to further protect nearby buildings. Battalio and Revell lean over the side of the pier to show where the metal wall directly beneath the pier’s snack shop has been worn away by the power of the surf combined with the sand that the waves throw at it. Battalio waves his arm across the scene. “This place is a one-stop coastal process training area,” he says.

He and Revell are part of a team of engineers and scientists from Philip Williams and Associates, a San Francisco environmental hydrology firm that recently looked at the potential effects of rising sea level on coastal erosion in California. Their work is part of a larger report produced by the Pacific Institute examining the physical and economic effects of sea-level rise on the state, which itself was one of almost forty produced for a biennial assessment by California’s Climate Action Team.

The results of the Pacific Institute report are startling. As the sea level rises, it will enlarge areas at risk of flooding while also increasing erosion risk; the report projects potential infrastructure loss statewide and wholesale disappearance of coastline along the central and northern coasts by the year 2100. Almost a half million people may have to live with increased flooding risks, which will also affect power plants, hospitals, and schools. Meanwhile, the ocean’s natural forces of erosion will increase with sea level—calculations suggest that northern and central California’s sandy coastal dunes could retreat an average of 170 meters by 2100, and cliffs could be cut back an average of 66 meters. The Bay Area, with its concentrated coastline and low-lying areas surrounding it, will be affected perhaps more than any other region. As the sea rises, Californians will be forced to decide: Should we adapt to the changing environment, or should we try to make it adapt to us?

Rather than letting the physical relationship for millions of years—which would require moving people, buildings, and infrastructure away from the ocean’s advance—planners and engineers have tried to arrest the natural order. As a result, any beach that might exist along that stretch of coast has no chance of surviving, because the sea consumes it from one side while development prevents natural resupply of sediments from the other.

Battalio and Revell expect similar tensions to play out in other parts of California, as communities make choices about whether to alter nature to preserve development along the coastline, or to accommodate erosion as the sea level changes. They believe that some of what makes coastal California special hangs in the balance. “Beaches and palm trees will be gone” in some places as the buffer between ocean and cities shrinks, Revell says, just as along Pacifica’s seawall, the beach was sacrificed for the buildings. “It adds a lot of passion to what we do,” says Battalio, “because it’s our future.”

The Pacific Institute’s draft report released this spring, called “The Impacts of Sea-level Rise on the California Coast,” attempts to provide a concrete perspective on what to many has been an abstract question: What will climate change mean to a developed society?

The scientific roots of this study (www.PacInst.org) can be found in a pair of small buildings perched above the San Francisco Bay waters just inside of the Golden Gate. These whitewashed structures with their red roofs look unremarkable, but the site, at the end of a locked boardwalk, is part of the National Ocean Service’s network of tide gauges. A series of sophisticated chines have been measuring the bay’s tides since 1854, making this the longest continuous tide record in the western hemisphere. These 155 years of data show that since 1900, the mean sea level has been rising slightly more than two millimeters a year—eight inches in the last century. “We’re fairly certain that it’s going to continue rising,” says Matthew Heberger, a hydrologist and research associate at the Pacific Institute, “but that the rate is going to increase.”

Heberger performed some of the geographic information system analyses that underpin the report’s findings, using sea level rise and flood projections worked out by researchers at the Scripps Institute of Oceanography and the US Geological Survey, as well as topographic data for the coasts. Heberger and his colleagues concluded that the greatest threat from sea-level rise would come not from steadily creeping changes, but from occasional inundations in what are called “hundred-year flood zones,” which they expect will shift with the sea level. (The name comes from the idea that there’s a one-in-a-hundred chance that a flood could occur in this area during any given year.)

As sea level rise pushes the hundred-year flood zone boundaries higher, communities and infrastructure in
areas once thought safe will be at increased risk, including Fisherman’s Wharf, Crissy Field, Treasure Island, and the Bay Bridge toll plaza. Additionally, since it will take years for these flood zones to shift, people may build new roads and homes in areas that are considered fine now but will eventually be at risk.

“If you think about where we permit development,” Heberger explains, “you’re not supposed to build in a floodplain. … You’re supposed to build houses and factories and fires stations and all that stuff above the hundred-year-flood elevation.” However, he continues, “We’ve collectively, as a society, decided the one-percent annual chance flood—the so-called hundred-year flood—is what we use for a lot of our risk assessment and land-use planning.”

But figuring out exactly how much the sea might rise is tricky, especially since most reports on climate change scenarios have focused more on greenhouse gas emissions and surface air temperatures than on sea level. To predict sea level rise, says Heberger, a model has to account for other factors. “The big component of that is thermal expansion of the oceans. As water warms, it takes up more space. And the ice sheets, as they melt, they’re just putting more water in the ocean,” he says. “And that’s why there’s kind of a wide range of estimates. Because, first of all, we don’t know what the warming’s going to be because it depends a lot on what we do in the next year, ten years, twenty years, century.”

For the Pacific Institute study, researchers at the Scripps Institute of Oceanography provided projections based on the International Panel for Climate Change’s so-called A2 and B1 warming scenarios. Heberger describes the A2 scenario as “sort of a medium-high scenario. It’s one that a lot of people think is likely”—in it the sea rises 1.4 meters, or about four and a half feet, by the year 2100. The B1 scenario would be less severe, a one-meter rise. Heberger and his colleagues then mapped this potential sea level rise onto the areas at risk for hundred-year-floods to find out which elevations were at most risk of inundation.

If nothing is done to protect California’s infrastructure, and we get a 1.4 meter sea-level rise, several grim outcomes may be in store for the Bay Area. The Pacific Institute estimates some $100 billion in property would be at risk statewide; two-thirds of that is on San Francisco Bay, most of it residential. About 480,000 people will be exposed to the flooding, particularly in San Mateo, Alameda, and Orange counties; many of the most vulnerable may be in low-income households or minority communities along the bay, including portions of West and East Oakland and Richmond.

A good deal of the Bay Area’s public infrastructure would also be at risk, including the San Francisco and Oakland airports, more than 300 hazardous waste facilities or sites, thirty power plants, and 22 water treatment plants, as well as dozens of schools, firehouses and police stations. More than three thousand miles of road could also go under.

The damage would not only be to the built environment, but the natural one as well. This projected rise in sea level may expose 14,000 Californians who live near coasts to erosion hazards, and could mean the loss of 41 square miles of sandy dunes and cliffs. About 150 square miles of wetlands could be flooded. The Pacific Institute study’s authors point out that wetlands may “migrate” inland as the sea level rises; indeed the report recommends setting aside land near wetlands so that they can “migrate” as their shore boundary is eroded.

Terry Root, a biologist at Stanford’s Woods Institute for the Environment who has studied climate change’s effects on wildlife and habitats, says she worries that bay wetlands will be lost. “What’s going to happen to the estuaries, which are the coral reefs of terrestrial areas?” she asks. Like the beaches, with development on one side and a rising tide on the other, some wetlands may be squeezed in the middle and flooded out of existence. Even if they do persist, the species that rely on them, such as the clapper rail, an endangered marsh bird, may not.

If the sea level doesn’t rise quite as high as 1.4 meters within the century, it is still expected to change in the coming years. “Even if we brought our carbon emissions to zero miraculously today,” says Heberger, “there’s still a certain amount of sea level rise that’s going to occur. There’s this long time-lag effect, because the oceans are massive and they’re slow to respond.”

Policymakers and land managers are going to have to figure out how Californians will live with a rising sea. One possibility recommended by the Pacific Institute report is “coastal armoring”—engineering against the forces of the sea with seawalls, riprap revetments, levees, and other structures. The institute calculates that protecting threatened areas from flooding by installing such measures would cost $14 billion (the average seawall costs $5,300 per linear foot), plus an additional $1.4 billion in annual upkeep. But the authors remind us that there may be non-monetary costs, such as loss of beaches, coastal access, or habitats.

Beyond this kind of short-term fix, Californians will need to consider broader solutions that would make communities more adaptable to sea-level rise and more resilient if disaster occurs. These include fundamental changes like limiting development in at-risk areas, and creating insurance polices and planning strategies that accept the possibility of flooding. For example, if development
is allowed in at-risk areas, permits might mandate that after flooding, the area be allowed to return to its natural conditions. “You say, ‘Okay, you’re allowed to develop,’ and you have certain codes for flood-proofing and for raising structures—buildings on stilts, stuff like that on the coast—allowing for them to benefit economically from that now, but at some point in the future realizing that it’s going to need to be abandoned,” suggests Heberger.

Heberger also mentions the principle of “no repetitive loss,” which is taking hold in the risk management and insurance world. “Some properties just get flooded, make a claim, get flooded, make another claim. So they keep getting bailed out again and again and again, which isn’t sustainable,” he says. Instead, an insurer confronted with a property owner who has filed for several losses might decide to buy the owner out or declare the property derelict. “Otherwise,” points out Heberger, “it’s either taxpayers or other insurance premium payers that are bearing the burden for an unacceptably high level of risk.”

But the most radical idea for dealing with sea level rise would be to simply let erosion take its course. If you know that a house on the edge of a cliff is going to fall off in ten years, says Heberger, “Why not allow [the residents] to live there for the next ten years and experience the benefits of that? And then at the end of ten years, say, ‘Well, you had a good run.’” He chuckles. “Instead of building a massive engineering structure, or spending millions of dollars trying to replenish the sand or put boulders and riprap in front of it, which is potentially harmful for the other things we value about the coast, just allow natural processes to occur. Allow that erosion to happen. Allow it to come back into this balance that takes place.”

So far, it’s hard to tell whether ideas like these are making a dent in local planning policies. Susanne Moser, a geographer in Santa Cruz who has studied the relationship between climate science and local policy, surveyed coastal managers a couple of years ago about their policy views on climate change. “Some of them said, ‘Until I hear from Sacramento, sorry, I’m busy,’” Moser says. The problems such policy-makers typically face—the usual bureaucratic issues of budgeting and staffing—along with uncertainty about what climate change and sea-level rise might physically mean to their local jurisdictions, has slowed the incorporation of climate considerations into planning decisions.

This may be poised to change—after all, the Pacific Institute’s study was carried out in light of Governor
Arnold Schwarzenegger’s 2005 directive to report on climate change mitigation and adaptation plans, and the state’s Climate Action Team is due to release another report this summer. A few agencies are ahead of the curve; for example, the Bay Conservation and Development Commission is sponsoring the Rising Tides international design competition for how best to develop in an estuary in an environment subject to sea-level rise.

Still, there is, as Heberger points out, a kind of null hypothesis: “One choice is do nothing,” he says. “Whether that’s what a community decides to do or does by default, that may mean setting themselves up for increased flood damage, loss of life, closing critical facilities, roads, things like that. That’s [what] we’re trying to avoid.”

In Pacifica, Dave Revell and Bob Battalio stand on the edge of a bluff. The sea reflects the silvery sky. They have just shown me the eroding bluffs overlooking Mussel Rock, where the San Andreas fault sideswipes
Daly City as it reaches the Pacific Ocean. “The landscape is timeless,” Battalio says. “The vegetation, the topography—it just retreats along with the coast, unless you change the geometry,” by, for instance, putting in a seawall or dumping riprap at the base of an eroding bluff.

“In some ways, the solution is easy,” Battalio continues. ”All one has to do is get out of the way and let erosion occur,” allowing natural processes, such as beach formation, to play out on their own. But, he continues, “The hard thing is we have all flocked to the coast and staked our claims,” like the rows of little pastel pink and green houses that stand precariously at the bluff’s edge. The whole area is a complex of landslides. The engineers explain that erosion propagates up a bluff. “It’s just like digging at the base of a pile of sand at the beach,” says Revell. “The slope above it continues to fail.” If the sea-level rises and starts eating away at higher points on the bluffs, eventually the solid ground under these houses with commanding Pacific overlooks will crumble away.

“They’ve got a nice view, though,” says Battalio, cautioning against unfair judgment of whoever planned sites like these. After all, he says, they were, making decisions based on what people knew at the time.

Before we part ways, Battalio and Revell take me to Linda Mar, also called Pacifica State Beach. It’s a popular spot, especially on weekends, where people come to sunbathe and surf. Battalio was involved in a restoration project there several years ago, in partnership with the city of Pacifica and other organizations, because nearby infrastructure and oceanfront buildings had become threatened by the Pacific’s erosive forces. Battalio’s firm helped carry out a “managed retreat” strategy that would allow the beach to push inland naturally. They removed fill, demolished the sections of parking lot that impinged on the beach, bought and tore down a couple of beach houses, and restored native plants to stabilize sand dunes that once encroached on the nearby Highway 1. As we watch, birds fly out of a fourteen-acre wetland at the southern end of the beach, also part of the project. In this area, at least, Pacifica decided that rather than try to battle the ocean, it would get out of the way.

“This project gives the beach another ten to thirty years of recreation use,” says Revell. “If you could put a dollar amount on this, you’d have a lot more up and down the coast.” Moreover, the ocean has not encroached as much as expected.

Finding that balance that lets people make use of California’s beloved coastlines, yet deals with the physical realities of climate change, is still a work in progress. “A certain amount of change is inevitable. We are going to have to take steps to protect our built environment—and there are risks to the natural environment as well,” Matthew Heberger had told me at the Pacific Institute. “Preserving the built environment versus the natural environment are oftentimes at cross-purposes with one another. We need to come together to decide, in each community, what it is we value about the coast—whether that’s fishing, boating, beaches, habitat, recreation, wildlife, shipping—because you’re not going to be able to preserve all those values.”

There is an irony in the urgent situation Californians face now—after all, erosion and flooding are nothing new. For millennia, people have sited homes and roads based on nature’s dictates, or, sometimes, in spite of them. No matter what we do, there is a consequence down the line. You could install coastal armoring to hold back the ocean to preserve a road, but you might lose a beach. Buy that house with a million-dollar view overlooking the ocean, but if the bluff starts to give out from below, would you be prepared to simply give it up and let it return to nature? Erosion and flooding seem like such elementary forces of nature, but their patterns are being altered by climate change—a process to which human activity contributes. If our choices now have new and more alarming consequences, that is partly our own fault.

2 thoughts on “A Rising Tide

  1. Pingback: A Coast Process; or, New Magazine Story on Sea Level Rise | Timothy Lesle

  2. Sounds like a lot of west Pacifica will be under water or wetland in the next 20 years… too expensive to keep the sea out.