SFO plans to surround airport with 10-mile wall to protect against rising bay waters

San Francisco Bay is expected to rise at least 1 foot in the next 30 years and 3 feet or more by 2100. Both San Francisco and Oakland airport are at risk of major flooding.

Concerned that rising waves will flood runways and buildings in the coming years, officials at San Francisco International Airport are moving ahead with a $587 million plan to build a major new sea wall around the entire airport.

The plan, the latest example of the growing cost of climate change in California, involves driving steel pilings — sheets with interlocking edges — into the mud and also constructing concrete walls in some places around all of the airport’s 10-mile perimeter.

“This is something we’ve been looking at for many years,” said Doug Yakel, a spokesman for the airport. “What’s changed is the level of protection that is needed.”

The airport, built in 1927 in a cow pasture at the edge of San Francisco Bay, serves 55 million passengers a year, making it the nation’s seventh busiest. But its runways sit only about 10 feet above sea level.

The runways, terminals and other buildings are protected now by a series of earthen berms and smaller sea walls which the airport built mostly in the 1980s. But they provide only about 3 feet of protection from flooding.

Under the new project, whose fiscal plan was approved by the San Francisco County Board of Supervisors on Sept. 17, the airport will build five more feet of protection.

That should guard against 3 feet of sea level rise, plus another two feet for big waves during storms, airport planners said. And it should protect the airport through 2085, based on the most recent scientific estimates of sea level rise. Researchers project San Francisco Bay’s waters could rise 1 foot in the next 30 years and another 3 feet or more by 2100. Environmental studies are set to begin next fall, Yakel said, with construction starting in 2025.

The project will be funded with bonds and paid off through higher fees on airlines that fly in and out of SFO, according to airport officials. With interest on the bonds, the final price tag is estimated at $1.7 billion over 30 years.

Environmental groups, who successfully blocked SFO’s plans 20 years ago to build new runways into the bay, say they don’t have a problem with this project.

“We have no objection to this. The airport can’t be easily moved,” said David Lewis executive director of Save the Bay, in Oakland. “But adapting to climate change is going to be expensive. We can save ourselves a lot of money if we reduce the amount that we warm the planet, melt the ice caps, and raise the sea level.”

What’s happening at SFO is also an issue in other places.

Dozens of major airports around the world are located at the water’s edge. In some cases, parts of bays or harbors were filled in generations ago to construct new land for runways. In other places, the shoreline was chosen because it reduced noise problems from airplanes flying over neighborhoods.

“Nobody thought about sea level rise back then,” said Gary Griggs, a professor of earth sciences at UC Santa Cruz who has studied oceanography for more than 50 years. “They put in fill, got it a few feet above sea level and thought they were good. Now they don’t have a lot of options.”

At Oakland International Airport, construction is set to begin next year on a $46 million project to raise a 4-mile earthen dike by two feet to guard runways against rising bay waters.

“Sea level rise is a very big focus of airports both in the U.S. and globally,” said  Kristi McKenney, assistant director of aviation for the Port of Oakland, which owns the airport. “The recent hurricanes in the Caribbean shined a bright light on it. The airport industry takes this very seriously.”

San Jose’s airport is not facing the same threat. It sits nearly four miles inland from the bay.

The Earth’s temperature continues to rise as fossil fuels are burned and heat is trapped in the atmosphere. The 10 hottest years since 1880, when modern temperature records began, all have occurred since 1998, according to NASA and NOAA. The planet has warmed 1.8 degrees Fahrenheit in the last century, and is expected to warm another 2 to 4 degrees this century at the current rate.

“As you heat water, it expands, just like in your water heater,” Griggs said. “And the warmer it gets, the more ice melts. Ice melts at 32 degrees Fahrenheit. It doesn’t matter if you are a Democrat or Republican.”

According to tide gauges, San Francisco Bay has risen 8 inches since 1900. Scientists project it will rise another 1 foot by 2050 and another 3 feet or more by 2100. Heavy winter storms, especially during high tides, already cause flooding in some parts of the Bay Area. Waves have over-topped the berms and existing sea walls on occasion at SFO, causing minor flooding issues.

The trouble, scientists say, is that the rate of sea level rise has doubled in recent decades, and is expected to further accelerate. There is some uncertainty about just how high the oceans will go. It depends on how much more fossil fuel is burned in the coming decades and at what rate the ice sheets of Antarctica, Greenland and other ice-bound regions continue to melt, Griggs said.

Bay Area cities and counties have three choices, experts say. First, they can build and restore wetlands in some areas, like the former Cargill salt evaporation ponds in the South Bay. Wetlands buffer waves and storms, reducing flood impacts on the shorelines.

Bay Area voters in 2016 approved $500 million in new funding over the next 20 years for bay wetlands restoration and flood control projects when they passed Measure AA, a $12-per-year parcel tax in all nine Bay Area counties. The first grants went out last year.

Second, cities can build concrete seawalls and levees. That will be the option for important features that cannot be moved, such as airports, or the Embarcadero along the San Francisco waterfront. But it’s expensive.

San Francisco voters last year approved Proposition A, a $425 million bond measure to begin work on an enormous, 30-year, $5 billion project to rebuild the 3-mile long seawall along the city’s Embarcadero — which was built in the 1800s and is cracking and crumbling — all the way from Fisherman’s Wharf to the San Francisco Giants ballpark.

Finally, some areas are likely to be allowed to flood if the costs are too high to preserve them, like hay fields in the North Bay.

“From a global standpoint, there are parts of our world where we are going to adapt and parts where we are going to retreat,” said San Francisco Supervisor Aaron Peskin. “And there are certain places our society is going to need to armor. SFO falls in that category. The airport is one of the most vital transportation links in the state, the country and the planet. There’s nowhere else for it to go.”