[REN #707] Flooding Could Get Worse in California

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Picture of people wearing shoe covers in flood for Real Estate News for Investors Podcast Episode #707

A new study reveals that by the end of the century, a rise in the sea level could cause much more damage along the California coast than that of wildfires or earthquakes. The study is the first to analyze the potential damage caused by a higher sea level combined with big weather events by the year 2100. So if you own property near the coast, you might want to sell it within 80 years.

The study was done by scientists at the U.S. Geological Survey who say that even a small amount of change in sea level could cause massive amounts of damage when a big storm hits. They are estimating that in another 80 years, about 600,000 Californians and $150 billion worth of real estate will be at risk of extensive flooding. That’s three times the previous estimates that only took sea level rise into consideration. (1)
 

Future Events Will Only Get Worse

Patrick Barnard, of the USGS, says of the risk, “It’s not just some nuisance that’s going to pop its head up once in a while.” He says, “These are significant events that are going to recur and be ten times the scale of the worst wildfires and earthquakes that we’ve experienced in modern California history.”

Stormy weather has already caused vast amounts of erosion that will only get worse with higher water levels and pounding rainfall. As reported by the Los Angeles Times, local governments have been dealing with erosion up and down the coast, like the destruction of a board walk along Capistrano Beach last winter, and the flooding of Imperial Beach when waves crashed over the sea wall. (2)

The new study says, future events will only get worse as the sea level gets higher. Jack Ainsworth, of the California Coastal Commission, told the LA Times, “This sort of science is absolutely critical to our planning.” He says, “It may seem like a slow-moving disaster, but we see how the fires amped up really quickly and destroyed communities… We really need to work with a sense of urgency.”
 

Higher Sea Levels and Bigger Storms

The study combined data on wave action, tides, erosion, and flooding along the coast with a sea level increase from 0 to 6.5 feet. It also included four types of weather conditions including the daily average, a typical once-a-year storm, a 20-year storm, and a 100-year storm. All those conditions were then integrated into a more in-depth look at the impact on people and property by including population data, property values, and other information from local, state, and federal agencies.

Barnard says, “It’s not just sea level rise that we need to consider when assessing the impacts of climate change, but it is also the combination of sea level rise with storms and every daily high tide we experience along the coast.” (3)

In a worst-case scenario, scientists combined a six-foot rise in sea level with a 100-year storm. They say that would put more than 600,000 people at risk. They say the risk represents a dollar value that’s 6.3% of the California GDP and just .3% of the state’s real estate. If you factor in population growth trends by 2100, the flood impact could affect more like 3 million people. And, they say, some California policymakers believe we could see an even higher rise in the sea level, to almost 10 feet.

When they looked at a six-foot rise in sea level combined with a typical annual storm, the damage was still massive. The analysis shows that the storm would threaten 483,000 residents and property worth about $119 billion. That’s less than the projected financial impact of a magnitude 7.8 earthquake along the southern San Andreas fault, which is estimated at $200 billion. But, it’s also about the same as the $127 billion in damages caused by Hurricane Katrina.
 

Storm Damage Will Ripple Through Economy

They also say, “The alarming scale of these impacts does not account for the ripple effects such extreme events have across economic sectors such as those related to closures of ports, disruption of transport of goods and services, business closures, and impairment of utilities.”

California does have a system of levees that offer some protection against high-water events, but the scientists say “the engineering integrity of most of these structures is poorly understood.” That also goes for things like sea walls and berms in estuaries, and along the coast. They say, “Some will undoubtedly fail and expose more people and property to a risk that isn’t covered by this analysis.” They suggest the need for further evaluation of these flood protection structures.

They say, California coastal managers and engineers should make use of this information to address the growing risk from more typical storms. Barnard says, “For those annual storms to expose $50 billion to more than $100 billion of property by the end of century, that’s just a massive number. That’s something that could happen every single year, not just maybe once a mortgage or once in a lifetime.”

The analysis was centered on highly developed coastal communities in both Southern California and the San Francisco Bay Area. 95% of the state’s coastal population live in those two areas. Scientists say in their abstract that their results “highlight the importance of including climate-change driven dynamic coastal processes and impacts in both short-term hazard mitigation and long-term adaptation planning.”
 
Links:

(1) U.S. Geological Survey Study

(2) LA Times Article

(3) Planning for the Future: USGS

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