Beach erosion, bluff collapse, flooding: What a foot of sea-level rise could mean for San Diego

Beachfront homes in Del Mar have rip-rap piled on the beach to prevent storm damage.
Beachfront homes in Del Mar have rip-rap piled on the beach to prevent storm damage.
(John Gibbins/The San Diego Union-Tribune)

San Diego leaders say they have a handle on rising tides. Some aren’t so sure.


Climate change is warming oceans and melting glaciers, accelerating the rise of tides and coastal flooding at a frightening pace. A recent scientific report confirmed the United States will see another foot of sea-level rise by 2050 — as much increase as the country experienced over the entire last century.

The San Diego region has started bracing for the inevitable impacts, some of which are already here: crumbling seaside cliffs, eroding beaches and periodic flooding along stretches of its 70-mile shoreline.

While local leaders have reassured the public the issue is in hand, some fear it’s not being taken seriously enough. Topping the list of concerns are the stability of train tracks along the Del Mar bluffs and beach erosion in places such as Oceanside and Carlsbad. Add to that fears about coastal real estate, buried nuclear waste and even the long-term viability of San Diego’s downtown airport.

“It’s coming, and if we don’t prepare for it, we’re going to get caught out in a few decades,” said Helen Fricker, a glaciologist studying sea-level rise at UC San Diego’s Scripps Institution of Oceanography. “It’s really bad.”

The report, led by the National Oceanic and Atmospheric Administration, NASA and the U.S. Geological Survey, found that projected sea-level rise over the next three decades will likely happen even if planetary emissions are sharply curbed in coming years. However, increases of up to five-plus feet by 2100 can be avoided with aggressive action to rein in climate pollution.

The eastern seaboard is predicted to get hit the hardest, with rising seas up to 14 inches in some areas. California’s coast is expected to see impacts materialize slightly slower, with around eight inches of rise by midcentury. These rates are influenced by everything from ocean currents and temperatures to sinking lands.

An Amtrak Surfliner train travels along the bluffs in Del Mar.
(John Gibbins/The San Diego Union-Tribune)

Del Mar bluffs

Perhaps the most pressing concern when it comes to rising tides in the San Diego region are the crumbling cliffs along Del Mar, atop which are precariously perched railroad tracks that service both freight and passenger trains.

Experts say, if something isn’t done to address the issue, another foot of sea-level rise will spell doom for the only rail connection between San Diego and Los Angeles.

Erosion from waves, coupled with urban runoff, chews away at San Diego’s coastal bluffs at a rate of six inches a year on average, according to local researchers. However, coastal retreat can also happen suddenly, up to 20 feet at once in some cases.

Several bluff collapses in Del Mar over recent years have brought the issue into stark relief, including a major failure in 2019 over Thanksgiving weekend and then another event the following February that came within feet of the railroad ties.

The San Diego Association of Governments, the region’s primary builder of transportation infrastructure, scrambled to reinforce the cliffside last year using a roughly 300-foot seawall. That emergency project came on top of four long-term stabilization efforts over the last two decades.

However, officials have said those are only temporary fixes. SANDAG is now working on a roughly $3 billion project to relocate the tracks inland by 2035.

“We have a problem out there right now,” said Keith Grier, principal regional planner with SANDAG. “We need to do the engineering and get the construction moving. It all comes down to funding.”

In May 2017, bulldozers pushed sand up onto the beach after it was pumped from the Oceanside harbor.
(John Gibbins/The San Diego Union-Tribune)

Beach erosion

Beach erosion is a major issue for San Diego’s relatively narrow band of sandy coastline. Another foot of rising seas promises to dramatically complicate efforts to preserve these iconic shores, which are a significant part of the region’s more than $19 billion annual tourist economy.

Ocean waves naturally eat away at California’s cliffs, creating new sand as seas advance. However, that equation has been upended in place such as San Diego, where often-opulent waterfront houses line long stretches of public coast.

Cities from Oceanside to Imperial Beach have tried to slow this natural process by dredging massive amounts of sand from lagoons and other sources, pumping it onto their beaches. In some places, communities have built seawalls, which prevent cliff erosion but at the cost of submerging shoreline under the advancing tide.

The alternative is what’s known as “managed retreat,” where homes and other structures are removed in order to maintain the shoreline. Leaders in Imperial Beach have talked about this possibility, but more affluent areas have largely sidestepped the conversation.

Carlsbad recently slammed Oceanside over a plan to install jetty-like rock groins that could help slow beach erosion but prevent the natural follow of sand to the south. Expect these types of fights to get more heated as seas rise.

“Because I grew up in Southern California, the thought that we might lose a lot of our sand beaches is heartbreaking,” said Mark Merrifield, oceanographer with Scripps Institution of Oceanography. “One of our precious natural wonders is at risk here.”

El Nino events can create a temporary foot of sea-level rise that provide a glimpse into the future, Merrifield said. “Those are the times when beaches really erode. That’s when you start to see cobble on the beaches. That’s kind of a scary look into the future. Are we going to end up with a cobble coastline?”

October 2019: With the San Onofre Nuclear Generating Station in the background surfers exit the water.
With the San Onofre Nuclear Generating Station in the background, Kaia Howard and her surf coach Greg Kessler exited the water at San Onofre State Beach in 2019.
(Hayne Palmour IV/The San Diego Union-Tribune)

Nuclear waste

In 2020, dozens of steel canisters filled with nuclear waste were put into a storage facility about 100 feet from the ocean at the now-defunct San Onofre Nuclear Generation Station. The spent fuel is buried in concrete about 20 feet below ground and behind a 28-foot seawall.

Some have raised concerns about the more than 3 million pounds of nuclear waste, saying the situation is ripe for catastrophe, especially as tides continue to rise.

Charles Langley, executive director of the El Cajon-based Public Watchdogs, fears that canisters will eventually crack and leak radiation if they’re exposed to saltwater sea spray.

“Our concern is that it won’t even take a tsunami to trigger a potential radiation release at San Onofre,” said Langley. “We think that rising sea levels could breach the ground-level silos that hold the canisters with disastrous consequences.”

Southern California Edison, which owns the facility, dismissed these concerns. Spokesman John Dobken said the situation is currently stable, especially because of a rock barrier installed along the coast to prevent erosion.

“With the rock revetment that we have out front, we really are good for another 30 years,” he said.

However, it’s not clear what happens after that. It would take an act of congress to authorize moving the spent fuel. There are roughly 80,000 tons of nuclear waste stored at various locations around the country, and so far, elected officials haven’t been able to agree on where to permanently store it.

March 2020: A Southwest Airlines jet approaches San Diego International Airport.
A Southwest Airlines jet approaches San Diego International Airport.
(K.C. Alfred/The San Diego Union-Tribune)

San Diego airport

The San Diego International Airport and the surrounding Midway District will be particularly vulnerable to flooding as tides rise, according to researchers. The area is bordered by not only San Diego Bay to the southwest but San Diego River to the north.

The Airport Authority said it’s been preparing for sea-level rise for the last decade, adopting an adaptation blueprint in 2012 and a climate resiliency plan in 2020. Officials said that’s led to actions like raising the building pad for a new airline support facility on North Harbor Drive to avoid future flooding. The authority also said its new $3.4 billion overhaul of Terminal 1 was designed to withstand rising seas through the end of the century.

However, not everyone is convinced. Environmental advocates are concerned that a plan to run an unground trolley line between Santa Fe Depot and the airport could be complicated by not only rising seas but increasing groundwater levels. There also are questions about the wisdom of siting a proposed $4 billion San Diego Grand Central transit hub in the Midway District just north of the airport.

“We’re definitely pushing them to take it seriously,” said Noah Harris, transportation policy advocate for the San Diego-based Climate Action Campaign. “There’s a sentiment out there that we can engineer our way out of these climate impacts, but can we really? These are multibillion-dollar investments, and we want the infrastructure to be climate resilient for a long time.”

SANDAG officials said they feel comfortable building the proposed transit hub in the area because officials wouldn’t cede the existing neighborhoods to flooding without first building massive seawalls and other structures. The agency also said that any tunneling would accommodate for the threat of groundwater intrusion, potentially with drainage and rust-resistant materials.

“It’s not just about the Central Mobility Hub,” said Grier with SANDAG. “It’s the entire area of Midway. It’s even up into Old Town. So you need to do something more to protect those existing structures, as well as accommodating future structures.”

Other areas around the region that could be impacted by increased flooding include parts of Highway 101, especially in Carlsbad; the Bay Shore Bikeway in the Chula Vista, and coastal wetlands and marshes, such as the San Diego Bay National Wildlife Refuge. Buried sewer and water lines will also be vulnerable as the water table rises.

Engineering, seawalls and human-placed rock known as riprap should be able to address many of the concerns posed by a foot of sea-level rise. However, if global emissions don’t start to come down dramatically in coming decades, humanity many not be able to hold back the ocean for long.

“It’s getting to the point where in somebody’s lifetime now, they will notice the difference,” said Fricker with Scripps.