Sea-level rise and the Bay Area

Although millions of people live in the Bay Area, we are remarkably detached from any connection with the actual Bay. We drive around it, sail on it, BART under it, bridge over it, and fly to airports along its margins. But for many of us the Bay itself resides on the periphery of our daily existence. That will change in the coming years, as global climate changes begin to make themselves felt to local communities around the world.

One of the most likely consequences of our warming of the globe is a rising ocean, as ice caps flow into the sea and as the oceans themselves warm and expand. Our days of mental, and indeed literal, detachment from the Bay may be coming to an end..

Sea level in San Francisco Bay has already risen more than nine inches since the middle of the 19th century and the rate of increase is accelerating. The 2007 report from the Intergovernmental Panel on Climate Change predicts sea levels to rise between eight and 23 inches by 2100; it notes that "larger values cannot be excluded." With sea-level rise, the extensive and valuable real estate along the margins of our Bay will be increasingly vulnerable to storms and high tides. Our major airports, highways, transmission lines, bridge access, power plants, wastewater treatment facilities, businesses, and homes will all be exposed to rising oceans. Storms that we used to handle adequately will become far more damaging with even modest increases in sea levels.

California's drinking water is vulnerable as well. As sea levels rise and push salty water inland, our water-supply system, with its heart in the Sacramento-San Joaquin Delta, is going to face more frequent and more severe saltwater intrusion. The risks of levee failures in the Delta will threaten water quality and reliability for millions of people. And as seas rise around the entire Bay, levee failures will threaten low-lying inland communities and require costly retrofit, repair, and rebuilding.

The remaining wetlands throughout the Bay are the most vulnerable of all. These areas are home to the last of the incredibly rich marsh ecosystems that predated European settlement. They have survived the population and building booms of the past 150 years, but they will be unable to adapt to a rapidly rising sea level and are unlikely to receive the physical protection we may be willing to build to protect homes and businesses.

We have only two options, and we must pursue them hand in hand. We must work at all levels to reduce the emissions of greenhouse gases and avoid the rapid, severe climate changes that can still be prevented. Doing so requires us to adopt policies that conserve electricity, gas, and water (a significant drain on energy resources in California). But we must also work to address and mitigate the impacts that we cannot prevent. This means rethinking all development rules around the margins of the Bay to put in place buffers for expected sea levels. We must redesign disaster insurance to prevent inappropriate new construction and to stop rebuilding in risky areas after catastrophes occur. Wetland areas and protected lands should be expanded inland so that ecosystems can, at least to a degree, adapt over time. And we must look at the Bay with new eyes, as a resource to be protected and respected. This is, after all, the Bay Area.

Peter H. Gleick Peter H. Gleick, Ph.D., is president of the Pacific Institute for Studies in Development, Environment, and Security, a nonpartisan Oakland-based think tank. He is a MacArthur fellow and a member of the National Academy of Sciences. For more on the water-energy connection, visit www.pacinst.org