Abstract

A richly varied composite of urbanization and nature exists in and around San Francisco Bay. Urban waterfronts, critical habitat areas, industrial areas and residential neighborhoods coexist within walking distance of each other. Overlaid on these shoreline places is a vital system of public infrastructure, including freeways, seaports, railroads and airports, which knit the shoreline communities together and connect them to the rest of the region, California and the world. This tapestry helps make the beauty of the Bay Area world-renowned and underpins its economy, the health of its natural systems and the quality of life of its inhabitants. Over the past 150 years, the productive use of the Bay’s shoreline has become the cornerstone of the region’s prosperity and forged an inseparable bond between the people of the Bay Area and the Bay itself. The nine-county San Francisco Bay Area is home to approximately seven million people making the Bay one of the world’s most urbanized estuaries. Climate change has the potential to drastically alter lifestyles in the Bay Area. Such changes, along with new institutional priorities, are needed to reduce greenhouse gas emissions and moderate temperature increases attributed to global warming—to mitigate climate change. To some extent, the choice to alter lifestyles and institutional priorities now will reduce the degree to which the world must adapt to the effects of climate change. However, it is inevitable that over the next century global temperatures will increase 1° to 3° C (1.8° to 5.4° F). To deal with this increase in temperature, adapting to climate change and its impacts is both unavoidable and essential. Global warming is expected to result in sea level rises in San Francisco Bay of 16 inches (40 cm) by mid-century and a 55 inches by the end of the century. The economic value of Bay Area shoreline development (buildings and their contents) at risk from a 55-inch rise in sea level is estimated at $62 billion—nearly double the estimated value of development vulnerable to sea level rise along California’s Pacific Ocean coastline. An estimated 270,000 people in the Bay Area are at risk of flooding, 98 percent more than are currently at risk from flooding. In those areas where lives and property are not directly vulnerable, the secondary and cumulative impacts of sea level rise will affect public health, economic security and quality of life. By mid-century, 180,000 acres of Bay shoreline are vulnerable to flooding, and 213,000 acres are vulnerable by the end of the century. The area that will be vulnerable to inundation with a 16-inch sea level rise at mid-century corresponds to today’s 100-year floodplain. Extreme storm events will cause most of the shoreline damage from flooding. Changes in climate and sea level cause increase storm activity, which in combination with higher sea level, cause even greater flooding.