Santa Monica Must Prepare for Rising Sea Levels

(This article was published three years ago this month. SMa.r.t. believes its relevance has withstood the test of time. It has been edited for brevity). 

Three weeks ago Dr. David Revell gave a presentation outlining what sea level rise might mean for Santa Monica.

With the usual disclaimers about the uncertainty of all predictive modeling, he suggested that oceanographers are predicting for Santa Monica Bay a 2- to 5-foot rise by the year 2100. This range is not unusual since globally we are seeing a 1-inch rise per year while in Santa Monica Bay the rise has only been about one-eighth of an inch per year.

This discrepancy cannot endure for long, so sometime in the coming decades we might see a sudden increase in the size of our own sea level rise.

Although a one-eighth-inch rise per year now may sound trivial, the real punch comes when you add this to the typical 7-foot tidal fluctuations plus the 7-foot storm surge by periodic severe storms (which occur about once every 50 years). For example, 33 years ago, in 1983, a putative 50-year storm tore off the western third of the Santa Monica Pier, requiring a multi-million-dollar reconstruction that continues with upgrades to this day.

If we combine the 100-year storm with only a 3-foot projected sea level rise, we lose the parking lot north of the pier and the lifeguard station headquarters, part of Muscle Beach and about half the bike path north of the pier.

At a 6-foot sea level rise plus the 100-year storm, we would lose: large buildings along the boardwalk (the Sea Castle, Shutters, Casa del Mar), about half the buildings north of the pier, all the bike path and bathrooms plus virtually all the parking lots. Finally, Pacific Coast Highway would be cut at Channel Road. That level of damage would be a serious blow to the tax base of the City and its tourist industry, not to mention the temporary loss of PCH. It’s unclear in this scenario what would happen to the pier.

There are other, less obvious effects of sea level rise unrelated to storm surge, including the problem of possible saltwater intrusion into our water table, the destabilization of buildings during an earthquake due to an enlarged liquefaction zone and possible basement flooding from a raised water table.

Finally, we need to add the possibility of tsunamis generated by far-off earthquakes. In 2015 the National Oceanic and Atmospheric Administration examined 19 hypothetical earthquakes from across the Pacific for their tsunami potential and found only one that would have the potential to generate a significant wave (13 feet) large enough to endanger Santa Monica.

All the 18 other earthquake sources generated waves no higher than 7 feet, about as bad as a 50-year storm. While sea level rise and 100-year storms play out relatively slowly, a tsunami with the potential to hit Santa Monica would arrive in only 14 hours.

The last time we had a significant tsunami event was from Chile in 1960 with a wave less than 6 feet in height that came ashore 300 feet and halfway into the parking lots south of Pico Boulevard. If that tsunami were to come ashore along with a 5-foot sea level rise, it could generate a 19-foot wave that would scrub everything clear to the base of the Palisades Park bluff as well as put a dent into the first block south of Ocean Park Boulevard.

SMa.r.t. recommends the following concrete steps we can take today to be ready for the impact of the inevitable sea rise:

1. Initiate a study for preserving the pier. The pier is arguably our most iconic asset and deserves the highest level of long term protection. This might involve protecting it by lengthening or raising its breakwater, which will continue to lose its protective capacity. It might also involve planning how to physically raise the pier in place.

2. Initiate a long-term study with Caltrans to protect PCH, which will eventually have to be raised higher than its current elevation. Eventually, that raised highway will hit the ceiling of the McClure Tunnel. That choke point needs to be reevaluated in light of sea level rise before such speculative plans as the 4th Street crossover, the Wyndham Hotel expansion or covering the freeway are initiated.

3. Initiate a study of how to protect our beach assets (bathrooms, bike paths, parking lots). The study would identify cost-effective solutions, including when to retreat gracefully as opposed to the bankrupting cash hemorrhage of rebuilding them after every major storm.

4. Identify realistic funding sources commensurate with the challenge of protecting, adapting or retreating from our most valuable beachfront. This literal rainy day fund would grow slowly and be deployed periodically when needed .

More than 80 years ago, the Santa Monica breakwater was completed and over the decades the sand buildup from that breakwater, along with a one-time sand bonanza from dredging Marina del Rey, provided us about a 600-foot sand buffer to the ocean. That awesome buffer is the investment that now buys us time needed for our wealthy City to respond gracefully with a well-conceived plan to address the current sea level rise.

We should be as prescient today as our civic ancestors were then. Their stewardship has given us such priceless jewels as the pier, our beaches, Palisades Park and our own water system. We should not waste the gift of their wisdom. We need, literally, to “get ahead of the wave.”

Mario Fonda-Bonardi for SMa.r.t. (Santa Monica Architects for a Responsible Tomorrow)

Thane Roberts Architect, Robert H. Taylor AIA, Daniel Jansenson Architect, Building and Fire-Life Safety Commissioner, Ron Goldman FAIA, Samuel Tolkin Architect, Mario Fonda-Bonardi AIA, Planning Commissioner, Phil Brock Arts Commissioner.