While San Francisco, seen here from Treasure Island, is less vulnerable to rising sea levels than other parts of the Bay Area, portions of areas bordering the bay would be at risk.
Photo: Michael Macor, The Chronicle
A region at risk
Fifty years ago, Bay Area residents rallied around the call to save San Francisco Bay. Public action on an unprecedented scale reversed development tides that for more than a century had covered shallow waters with land for industrial parks and housing tracts, roadways and garbage dumps.
ABOUT THIS PROJECT
All credible forecasts indicate that climate change will cause sea levels to rise at an ever-more rapid pace in coming decades, including the waters of San Francisco Bay.
In the coming months, Chronicle Urban Design Critic John King will explore this challenge, including the perils facing the city’s crumbling Embarcadero, the potential rebirth of the South Bay’s salt marshes and the creation of a small city on man-made Treasure Island.
The region needs to prepare for these shifting tides. We can protect ourselves and adapt in ways that are enticing as well as scientifically sound. But to do this, the Bay Area must begin planning for that future now and upend a half-century of priorities that inhibit adventurous decision-making and design.
Now the challenge is more profound: to accommodate the bay’s impending expansion as it rises because of our warming planet. And to accomplish that in a way that won’t put our human and environmental resources at risk.
An abundance of scientific studies says the bay’s average tide could climb several feet or more by 2100, with most change coming in the decades after 2050. It’s an inexorable shift that threatens low-lying neighborhoods as well as the fish, birds and wildlife that need tidal flats to survive.
If sea levels were to rise 36 inches, the midrange increase through 2100 projected in the most recent study by the National Research Council, water would wash into San Francisco’s Ferry Building twice daily at high tide.
With just 16 inches of sea-level rise, the tollbooths of the Bay Bridge could be flooded during storms.
$35 billion worth of public property in San Francisco is at risk if sea-level rise by 2100 reaches 66 inches, the upper level forecast by the National Research Council.
Already, lanes on the ramps connecting Highway 101 to the Shoreline Highway near Mill Valley are closed regularly — 30 times in 2015 — because of high tides, a small but vivid hint of how profoundly our region will be altered in coming decades unless the Bay Area starts making plans now.
Annie Kohut Frankel of the California Coastal Commission educates the public at Pier 14 during a king tide in November 2015.