Pacific Institute study confirms CA slide into ocean

by Eric on March 12, 2009


Credit: Pacific Institute

Under a new study released by the Pacific Institute, rising sea-levels over the next century will “inevitably change the character” of the California coast. The study attempts to gauge the impacts of sea-level rise upon the environment, people, and infrastructure, and finds that if no action is taken losses from flooding and erosion will approach $100bn.

The key findings of the study:

  • Under medium to medium‐high greenhouse‐gas emissions scenarios, mean sea level along the California coast is projected to rise from 1.0 to 1.4 meters (m) by the year 2100. A series of maps for the entire coast of California demonstrating the extent of the areas at risk are posted at
  • A 1.4 meter sea‐level rise will put 480,000 people at risk of a 100‐year flood event, given today’s population. Populations in San Mateo and Orange Counties are especially vulnerable. In each, an estimated 110,000 people are at risk. Large numbers of residents (66,000) in Alameda County are also at risk. 
  • A demographic analysis identified large numbers of people at risk with heightened vulnerability, including low‐income households and communities of color. Additionally, adapting to sea‐level rise will require tremendous financial investment. Given the high cost and the likelihood that we will not protect everything, adaptation raises additional environmental justice concerns. 
  • A wide range of critical infrastructure, such as roads, hospitals, schools, emergency facilities, wastewater treatment plants, power plants, and more will also be at increased risk of inundation in a 100‐year flood event. This infrastructure at risk includes: 
    • nearly 140 schools; 
    • 34 police and fire stations; 
    • more than 330 U.S. Environmental Protection Agency (U.S. EPA)‐regulated hazardous waste facilities or sites, with large numbers in Alameda, Santa Clara, San Mateo, and Los Angeles counties; 
    • an estimated 3,500 miles of roads and highways and 280 miles of railways; 
    • 30 coastal power plants, with a combined capacity of more than 10,000 megawatts; 
    • 29 wastewater treatment plants, 22 on the San Francisco Bay and 7 on the Pacific coast, with a combined capacity of 530 million gallons per day; 
    • and the San Francisco and Oakland airports. 
  • We estimate that nearly $100 billion (in year 2000 dollars) worth of property, measured as the current replacement value of buildings and contents, is at risk of flooding from a 100‐year event with a 1.4 m sea level rise if no adaptation actions are taken. An overwhelming two‐thirds of that property is concentrated on San Francisco Bay. The majority of this property is residential. 
  • Large sections of the Pacific coast are not vulnerable to flooding, but are highly susceptible to erosion. We estimate that a 1.4 m sea‐level rise will accelerate erosion, resulting in a loss of 41 square miles of California’s coast by 2100. A total of 14,000 people live in areas at risk of erosion. In addition, significant transportation‐related infrastructure and property are also at risk. Throughout most of the state, flood risk exceeds erosion risk, but in some counties, coastal erosion poses a greater risk. 
  • Coastal armoring is one potential adaptation strategy. Approximately 1,100 miles of new or modified coastal protection structures are needed on the Pacific Coast and San Francisco Bay to protect against coastal flooding. The total cost of building new or upgrading existing structures is estimated at about $14 billion (in year 2000 dollars). We estimate that operating and maintaining the protection structures would cost approximately 10% of the initial capital investment, or around another $1.4 billion per year (in year 2000 dollars). 
  • Continued development in vulnerable areas will put additional areas at risk and raise protection costs.
  • Vast areas of wetlands and other natural ecosystems are vulnerable to sea‐level rise. An estimated 670 square miles, or 430,000 acres, of wetlands exist along the California coast, but additional work is needed to evaluate the extent to which these wetlands would be destroyed, degraded, or modified over time. A sea‐level rise of 1.4 m would flood approximately 150 square miles of land immediately adjacent to current wetlands, potentially creating new wetland habitat if those lands are protected from further development.

The study report with associated maps and GIS data is available at the Pacific Institute website.

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