For more than 100 years after the Gold Rush, San Francisco Bay shrank by a third as new Californians diked and filled its shallow waters for farms, salt, dumps, ports, airports, homes and businesses.
Now the Bay is growing again. Rising temperatures are melting miles-thick glaciers off the land masses of Antarctica and Greenland. Rising seas are nibbling at low-lying land — and what's been built on it.
What does this mean for the Bay Area? And what can be done about it?
On Dec. 4, the San Mateo County Board of Supervisors heard a lively, powerful and ominous description of the problems of rising seal levels in the Bay Area. The speaker was Will Travis, executive director of the San Francisco Bay Conservation and Development Commission (BCDC), a regional agency created in 1965 to protect the Bay.
The good news, Mr. Travis said: "The Bay lost to filling would once again become part of the Bay. The bad news: We have all kinds of expensive stuff on that land."
Mr. Travis showed maps, prepared by BCDC, that showed what the Bay Area would look like if the sea rose by one meter — three feet. That rise could come by 2100 — or sooner, or later — according to studies by the California Climate Action Team, he said.
In San Mateo County, San Francisco Airport could be under water. In some areas of Palo Alto, water could lap beyond Bayshore Freeway; in Redwood City, it would come close to the freeway.
In Menlo Park, the map shows the Bay extending across Bayfront Expressway into Bohannon Industrial Park and Tyco Engineering. Highway 84 approaching the Dumbarton Bridge, parts of Sun Microsystems and Menlo Business Park are also shown in bright blue.
The regional sewage plant on the tip of Redwood Peninsula, and the former Marsh Road sewage plant, which is maintained to hold storm overflows, would need higher, stronger levees.
The maps should convey the message that climate change is not just about polar bears in Alaska and penguins in Antarctica, Mr. Travis stressed. "It will have a profound effect on our region, and it is something we must do something about now.
"We can't allow cities to go under water. We're going to have to build lots of levees."
"It's a double challenge," Mr. Travis added. "Levees have to be big and strong enough to withstand rising water — and to resist an earthquake."
Government agencies are responding, Mr. Travis noted. Four regional agencies are working together to address climate change. The Bay Area Air Quality Maintenance District (BAAQMD), the Association of Bay Area Governments (ABAG), the Metropolitan Transportation Commission (MTC), and BCDC have created a Joint Policy Committee (JPC), which will coordinate efforts and prepare a New Bay Plan to meet the challenges of climate change — including rising seas.
"We can't do it independently," Mr. Travis said. "We have to work together. We are doing that."
The county supervisors were impressed by Mr. Travis' presentation, which he has been taking around the Bay Area to rave reviews. He was in Palo Alto in December and Mountain View last week.
Supervisor Rich Gordon, who represents the county on BCDC, commented, "It's scaring the hell out of a lot of people."
Is three feet enough?
Sea level has already started rising in San Francisco Bay. Mr. Travis showed a slide from the oldest tidal gauge in the country, at the Golden Gate; it showed the Bay rising six inches in the 20th century.
"We know that sea level is rising. We just don't know how fast and how high the water will get," Mr. Travis said.
Mr. Travis based his projections on the report of the California Climate Change Team. This looked at three scenarios leading to temperature increases between 3 and 10 degrees F. "If we're effective at reducing greenhouse gas, maybe three degrees; if it's business as usual, 10 degrees," he said.
A three-degree temperature increase would raise sea level 5 to 7 inches by 2100, he said; business as usual would raise it one meter.
What about higher projections? We've all read and heard of studies that predict sea level rise of 20 or 40 or even hundreds of feet — far more than the one meter analyzed by BCDC.
Mr. Travis acknowledged the rise in sea level could be far higher than one meter. This projection reflects the expansion of water due to warming in the world's oceans. It does not include water released by accelerated melting of ice caps in Greenland and Antarctica — which scientists say might add another five to seven meters — he said.
BCDC relies on official estimates from California and international groups. "We will wait until scientists reach conclusions. We won't engage in debates," Mr. Travis said.
Sea level rise is just one of the challenges that climate change is bringing to the Bay Area.
Another effect of global warming is more frequent, more intense storms, Mr. Travis said. "The kind of event we once had once a century will happen ten-times as often. We'll have a surge-induced flood every 10 years."
Even today, the Midpeninsula endures occasional storms that overflow San Francisquito Creek, and flood low-lying areas near the Bay. Flood waters from the creek combine with a high tide and strong winds in a storm surge that can submerge approaches to the Dumbarton Bridge and vulnerable areas of East Palo Alto and Menlo Park.
Mr. Travis listed other challenges that will confront the Bay Area as thermometers creep up. More volatile weather will produce more heat, drought and wildfires. More rain will fall and less snow. "Water will rush into our rivers; it won't be stored as snow in our mountains for free.
"Increased winter runoff will bring more fresh water into the Bay," he said. "In summer you'll see salt water creeping into the Delta." That's where big pipes collect fresh water for Central and Southern California.
"We need new ways of using, moving, and storing water in California."
"This is the biggest issue of our lives. Seventy percent of our precipitation is water and not snow," responded Supervisor Mark Church. "Think water. The next eight years are critical."
Mr. Travis warned: "We're in much the same position as the captain of the Titanic. Once he looked up and saw the iceberg, it was too late to avoid the collision.
"Even if we shut off all the lights, parked all the cars, and mothballed all the power plants, there's so much greenhouse gas in the atmosphere, it will continue to get warmer for the next three-to-four decades."
So sea level will continue to rise, for a while at least, no matter what we do, Mr. Travis said. But we should get started.
What needs to be done?
The BCDC map for the Midpeninsula Bayfront clearly shows the challenges planners — from local to federal — will face.
They will have to decide what to do about each property or development threatened by rising seas.
Is the development or building valuable enough to be worth protecting it by expensive levees? If it is of low value, would it be more economical to relocate it or let it revert to the Bay?
The most contentious issues may focus on low-lying lands that are being planned for development. Like the 1,433 acres of former salt ponds owned by Cargill between Seaport Boulevard in Redwood City and Bayfront Park in Menlo Park.
"You're going to have a front row seat to a drama that is going to play out in San Mateo County which confronts the issue of how do we build on the shoreline," Mr. Travis told the supervisors.
Cargill and its partner, DMB Associates, want to develop the salt-crusted flatland for a mixture of uses, including housing, recreation and wetlands. DMB is conducting an elaborate outreach process to come up with a plan with a mix of uses that will meet the desires of Redwood City residents — and be proof against a potential referendum by opponents.
John Bruno, general manager for DMB Associates, said the company is prepared to comply with requirements imposed by city, state and federal agencies. "Our overall goal is to exceed the standards that are brought forward," he said.
Former county planning commissioner Ralph Nobles of the Friends of Redwood City is passionate that this land should be restored to the Bay, from which it was diked in 1901, as wetlands.
"The salt ponds were first marsh, and that's what they should return to," said Mr. Nobles, who has led two successful referendums blocking Bayfront developments. "The days of filling San Francisco Bay ended 30 years ago."
Mr. Travis views tidal marshes as magic in countering climate change. They absorb water; they buffer floods; they allow lower levees; and they sequester carbon, he said.
"Tidal wetlands are actually adaptive to climate change; they mitigate it; they help prevent it." Mr. Travis said. "It may be better to abandon plans than to allow development and face the costs of protecting it from flooding — which may be inevitable."
Mr. Travis warned that the Bay he is endeavoring to restore will be different from the Bay that people remember.
"We have to stop thinking about restoring the Bay to what it was and protecting it the way it was," he said. "Instead, we need to plan and design the Bay for what it will be in the future. It will have different water elevations, different chemistry, different temperatures, different species, and different salinity levels."
Mr. Travis' roving sermon is falling on receptive ears, certainly in San Mateo County.
"This is staggering in terms of what can and will happen if we don't take steps,' said Adrienne Tissier, president of the Board of Supervisors.
It turns out that the county and many of its cities are taking steps. They are calculating their carbon footprint and taking steps to reduce it.
Supervisor Tissier listed some of her priorities to reduce emissions: electrifying Caltrain; concentrating development near transit; encouraging businesses to recycle and reduce waste; promoting energy-efficient buildings.
"The best way to avoid rising sea levels is to reduce emissions as swiftly as possible," she said.
Menlo Park is looking at protecting Bayfront development — businesses such as Tyco and Bohannon — from rising sea level. "That's really, really valuable industrial land," said Councilwoman Kelly Fergusson. "We call it the breadbasket of Menlo Park. That's where our sales tax base is."
Ms Fergusson also worries about increasing intensity of storms tied to flooding of San Francisquito Creek. "We have to deal with that now. The effect of sea level rise is a few years off," she said.
Two other agencies are involved in protecting Menlo Park and East Palo Alto from rising sea level and storm surges. The Joint Powers Authority (JPA) for San Francisquito Creek is working with the U.S. Army Corps of Engineers on flood control in the creek and levees around the Bayfront. "The creek project is expanding to include tidal flooding," said Cynthia D'Agosta, executive director of the JPA.
The Corps of Engineers, which will be key to any levee construction, is also adapting to the new threats of sea level rise and extreme storms. It is studying shoreline levees in connection with the massive federal project to restore salt ponds around the Bay to tidal marsh and managed wetlands.
"We have a niche role to make sure that perimeter levees don't allow Silicon Valley to be flooded," said Tom Kendall, chief of the Planning Branch for the San Francisco District.
Mr. Travis remains an optimist even though major obstacles — government organization, laws, and cost — make a tough job tougher.
"The Bay Area is the only place more balkanized than the Balkans," Mr. Travis said. He referred to the nine counties and 110 cities that make up the Bay Area. "Twenty-six cities front on San Francisco Bay," he said.
Another obstacle lies in the powers of different agencies. Control over land use lies with cities; none of the regional agencies has the authority to block a subdivision. "We can't even say, 'You're a damn fool, but at least you have to build a sea wall to protect it,'" Mr. Travis said.
"The cost is going to be enormous. But we need to do it," he said. "The cost of dealing with climate change is far less than waiting and dealing with its ramifications later."
He said he believes the Bay Area has the wealth and talent and courage to deal with these problems.
"We need leadership to keep the Bay from reclaiming what was taken from it," Mr. Travis said. "We can provide leadership to meet this challenge around the world."
More information on climate change can be found at the following Web sites:
• http://www.bcdc,ca,gov ; click on climate change