Jutting out into San Francisco Bay, the quiet town of Foster City seems like the embodiment of the California dream. On any given day, boats and kayaks glide peacefully along a house-lined canal. Walkers and runners are a constant presence on waterfront paths. Seniors get a tranquil water view when working out at the recreation center.
Despite appearances, all is not well in this low-lying city. As climate change accelerates a rise in sea level, flooding is expected to become an annual event here by 2070, affecting 100 percent of Foster City’s residents. That’s the conclusion of new research released Wednesday by Climate Central, an independent scientific organization.
Foster City may be the California city most at risk for coastal flooding, but it’s hardly alone in the state known to be one of the most vulnerable to rising seas. Communities across California—especially those along the San Francisco Bay and the Sacramento–San Joaquin River Delta—will experience a three-foot sea level rise over the next 20 to 60 years, something not seen in the last 2,000 years, according to the study.
The regions hold about 90 percent of the 145,000 people and $36.5 billion worth of property lying in areas three feet below the high tide line.
Live on the West Coast and want to know if your house will be flooded in the decades ahead? Climate Central, New America Media, and Stamen Design have created an interactive data-mapping tool to show areas likely to be inundated as well as their socioeconomic vulnerability. (The West Coast study also looked at Southern California, Washington, and Oregon.)
“It’s very clear that sea levels are rising unusually fast, and the cause is us,” said Ben Strauss, Climate Central vice president and lead author of the study.
The risk is concentrated in Northern California, home to Silicon Valley and San Francisco, two of the state’s economic and cultural powerhouses.
San Mateo County is most at risk, with more than 92,000 people, or 12.8 percent of its population, residing less than three feet below the high tide line. Though the full effects of climate change–related flooding may be decades away, damage to roads, buildings, and other infrastructure will be felt sooner as storm surges grow stronger.
The map looks different when it comes to socioeconomic vulnerability, which takes into consideration income levels and the proportion of people of color living in vulnerable areas. In those terms, San Joaquin County, which lies inland along the river delta, would be most affected by flooding, said Ngoc Nguyen, New America Media’s environment editor.
“There is a perception that sea level rise only affects luxury waterfront property, but it’s certainly not just wealthy, predominantly white homeowners,” she said. The team mapped race, ethnicity, and income data, overlaid it with sea level rise projections, and found that the problem is not clear-cut.
“Numbers don’t tell the full story—look at East Palo Alto,” she said, referring to the low-income city that fronts the bay east of its more famous namesake. Right in Silicon Valley, “it has one of the highest jobless rates in San Mateo County, and the median income is half that of the rest of the county.”
The analysis, which took two years to complete, was based on data from a host of government agencies, including water level records and elevation data from the National Oceanic and Atmospheric Administration, sea level rise projections from the National Research Council, U.S. Census records, and Department of Energy power plant data.
If researchers are confident that flooding is inevitable, when it will happen is another matter, given the 40-year window of their projections.
According to Strauss, the uncertainty comes from a number of factors. “We don’t know how much carbon will be in the atmosphere,” he said. “Part of it comes from the sensitivity of sea levels to warming.”