The following is a brief paper I recently submitted as part of an assignment for the class Climate Change Literacy: Navigating Climate Change Conversations I am taking through the University of British Columbia. In this paper we are to identify and define a local phenomenon or effect of climate change – in my case sea level rise in the San Francisco Bay Area. The idea is to describe the region, make a claim regarding the specific climate effect or phenomenon and provide scientific evidence for that claim.
In a subsequent assignment we will discuss possible mitigation or adaptation efforts available to counteract the effects we describe in this assignment. For a more global look at the sea level rise, check out this infographic.
Sea Level Rise in the San Francisco Bay Area
Defining the Region
Located on the north-central coast of California, the San Francisco Bay Area is the largest estuary on the west coat of the United States. The coastal Mediterranean climate is generally characterized with a wet winter season and dry summer and fall.
The region has a wide diversity of topographical features, from coastal mountains and smaller bays to inland valleys. This variety of geography creates “micro climates” within the region, ranging from cooler coastal to warmer inland areas.
The confluence of the Sacramento and San Joaquin rivers comprise the Sacramento-San Joaquin Delta that drains into the northern edge of San Francisco Bay. The delta is an important source of many ecosystem services for both the bay region and the entire state, providing tidal marsh, biological diversity and habit for many species and a vital source of water for agriculture and urban water supply. Water from the Delta is also diverted through an extensive canal system to southern California and the dry Los Angeles basin.
The immediate Bay Area is divided into nine administrative counties with a total population of more than seven million people, making it one of the largest urban areas on the North American west coast and the fifth most populous metropolitan area in theUnited States.
The wide diversity of the region and its unique topography of land and sea make it one of the most biologically diverse areas in the world close to large urban development.
The combination of natural diversity and human development within the region presenta number of potential impacts and vulnerabilities to climate change, principal among these is the ongoing threat of sea level rise from thermal expansion and melting land-based ice.
The Golden Gate tidal gauge, the oldest continuously operating tidal gauge in the United States, has recorded an 8 inch (20.3 cm) rise in sea level in San Francisco Bay over the last century. A 2008 paper entitled Climate change projections of sea level extremes along the California Coast by Dr. Daniel Cayan et.al describes a 20-fold increase in extreme tides since 1915.
Using a semi-empirical climate model described in Climate Change and Sea Level Rise Scenarios for California Vulnerability and Adaptation Assessment (California Energy Commission) (Cayan et.al. 2012) future projections indicate an accelerating rate of sealevel rise over historical trends. By mid-century a rise of 11 to 19 inches over 2000 is possible and by 2100 reaching from between 30 and 55 inches.
The affects of this observed sea level rise include coastal erosion, flooding and storm surges and the consequent property damage.
As sea level rise continues into the 21st century, increasing salt water intrusion into the delta system will impact local marine and land-based habitats and water supply throughthe state. Local infrastructure including bridges, high tech campuses and two international airports are especially vulnerable. Storm surges will increase both inintensity and frequency (Cayan et. al. 2012).
Featured image credit: Eric Wagner, courtesy flickr