This article explores the research on how flooding due to sea level rise will impact California in the coming decades.

Unexpected consequences

Coastal residents of California are well aware of the increasing threat of sea level rise. Along the coast, property is susceptible to erosion, which translates to the loss of property. But residents of low-lying areas a distance inland from the ocean also need to be informed of the coming risks of flooding due to a rising sea level.

In the years to come, what residents have come to expect as minor floods will become major floods. For an example of the worst (and fairly likely) case scenario, recall the massive flooding that occurred in New Orleans during Hurricane Katrina, a situation that residents theoretically knew might happen, but for which they were still disastrously underprepared.

Globally, sea levels are expected to rise 3-9 inches by the year 2030, compared to sea levels in 2000. But the pace is quicker in California, where the sea level is anticipated to rise up to 12 inches in the same time period.

Sea level rise happens at different rates across the world. Areas with warming waters, like California, will see a higher rise. Seasonal weather patterns like El Niño contribute to differences in sea level, too.

Further, California’s fault lines are actually causing land to dip relative to sea level each year. The next large earthquake of magnitude 8 or greater is expected to cause a sudden land drop, paired with a sea level rise of 3-7 feet, according to the National Academies of Science, Engineering, and Medicine.

Other, more common sudden rises will occur when large storms hit California, which are often worse during El Niño years. Warming seas will likely create larger storms in the future, and more flooding.

It’s these rapid increases in sea level that California residents need to be concerned about, since these will potentially cause flooding in low-lying areas even miles inland from the coast.

Northern and Central California

Since 1900, the Bay Area has experienced a moderate eight-inch rise in sea level. By 2100, scientists expect sea level to have increased at minimum three-to-five-and-a-half feet in the Bay Area, according to the State of California Ocean Protection Council.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Economic centers like the San Francisco airport will be increasingly prone to flooding as sea levels rise. The Pacific Institute estimates the economic impact of flooding in San Francisco at $4.9 billion (not adjusted for inflation from the year 2000). Damage in nearby San Mateo from flooding may surge as high as $24 billion, and $15 billion in Alameda.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

The coast near Monterey Bay is also at risk of flooding. Flooding in low-lying Salinas has the potential to destroy homes and farmland, costing over $2 billion in property damage, though the total economic cost will likely be even higher when accounting for the loss in agricultural activity.

Southern California

The coastal area south of Monterey and north of Pismo Beach won’t be much impacted by flooding in the coming years, mostly due to the high cliffs that line the coast. However, these cliffs are susceptible to other types of damage from sea level rise, notably erosion and landslides.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Sea level rise will increase the amount of land in Pismo Beach susceptible to major flooding 13% by the year 2050, according to the City of Pismo Beach. In addition to the loss of property, freshwater wells may become permanently inundated with saltwater, which will harm an already dwindling water supply.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Santa Barbara estimates around 55 inches, or five-and-a-half feet of sea level rise by the year 2100. The economic effect of flooding is expected to reach up to $1.1 billion in Santa Barbara, according to the Pacific Institute.

The California Energy Commission forecasts Santa Barbara will face a moderate risk of flooding in the year 2050. This will worsen each year, and by 2100 the city will face a very high risk of flooding. The current choices facing Santa Barbara including adapting by building seawalls and other barriers, or abandoning the coast and other low-lying areas to the flooding very likely to occur in the coming decades.

Many of Santa Barbara’s storm drains empty out onto the beach. During strong storms when waves are high — to be worsened by sea level rise and warming oceans — these storm drains become clogged by seawater, resulting in flooding far inland from the coast.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Coastal Resilience Ventura observes vulnerable populations like low-income, the elderly and very young will be most impacted by future flooding in Ventura due to sea level rise in the coming decades. At today’s population density, 16,000 people reside in these flood-prone areas.

Ventura County also supports agricultural activity, and 10% of residents rely on income directly or indirectly related to this industry. Coastal Resilience Ventura identifies some farmland that will be susceptible to flooding, but much more will be affected by saltwater inundation of groundwater, which will be worsened when sea levels rise.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

A study by the University of Southern California (USC) observes sea level rise will impact Santa Monica’s large tourism industry, which relies on its wide, sandy beaches. Likewise, beaches along the Pacific Coast Highway will need to be shored up to prevent flooding of the highway during storms.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

The Port of Los Angeles, seen in the map above, receives 40% of all U.S. imports, according to the USC study. The port is currently susceptible to flooding during storm surges, but the impact will only worsen in future years as sea level rises. The port is well aware of the danger and is pursuing ways to strengthen its barriers. But the entire city will need to be prepared, since roads leading to and from the port will need to be accessible for ground transport to carry goods inland following storm surges.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Flooding due to sea level rise will potentially cost residents $17 billion in Orange County, according to the Pacific Institute.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

A report in the New York Times estimates Huntington Beach will be 27% flooded by the year 2100 if no progress is made to halt sea level rise.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

Image courtesy the Pacific Institute. Blue areas are current areas at risk of flooding. Pink areas are the areas at risk with a four-foot sea level rise.

San Diego is in much better shape than other Southern California cities, as sea level rise is likely to cause just minor flooding in the coming decades. In total, a major flood due to sea level rise will cause up to $2 billion in damage in San Diego County, according to the Pacific Institute.

Very few residents are at risk of flooding by the year 2050. But by 2100, more residences will be under threat from a large flood. The San Diego Airport will also be under threat from flooding, according to the San Diego Foundation.

What California residents need to know about sea level rise in the future

Californians need to decide: abandon the coasts? Or build barriers to protect residents and economic activity in densely populated areas like Los Angeles and the Bay Area?

Of course, abandoning the coasts entirely is out of the question. But estimates for not preparing for sea level rise range from four to ten times the cost of simply installing proper barriers and taking mitigation efforts to lessen the impact of flooding, according to the Orange County Register.

Residents living on or just above sea level need to be aware of the future risks, which will only increase as seas rise. That’s not to say they ought to move or relocate to higher ground. But they need to prepare for the eventuality of future flooding, including the probable impact on home values in flood prone areas, which they need to consider in negotiating today’s price.

Likewise, private property owners on the coast may need to invest in barriers against flooding, like seawalls. Residents of the city can also prepare for future tax increases to pay for the mitigation and prevention costs associated with sea level rise as local government make preparations. These preparations are already in the works, as most local coastal cities have commissioned reports on the likely impact of sea level rise and flooding in their communities.