Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present and Future

This study provides the first comprehensive regional projections of the changes in sea level expected in California, Oregon, and Washington - posing serious risks to the infrastructure, development, and wetlands along this 1,600 mile shoreline. California Executive Order S-13-08 directed state agencies to plan for sea-level rise and coastal impacts, and asked the National Research Council (NRC) of the National Academies to establish a committee to assess sea-level rise. Oregon, Washington, and several federal agencies joined California to sponsor the study. The report estimates sea-level rise both globally and for those three states for the years 2030, 2050, and 2100. 

Global sea-level rise and the contributing factors are described in scientific detail, and the NRC's findings are compared to the UN's Intergovernmental Panel on Climate Change's (IPCC) 4th Assessment estimates. Sea-level variability and change for the region is evaluated - based on the current contributions of ocean circulation, short-term climate patterns and storms, modern land ice changes, and vertical land motion to sea-level rise in each state. The methods for projecting global and regional sea-level are detailed, along with the specific state and local projections quantified for the west coast. Existing information is summarized on the susceptibility and responses of coastal habitats to sea-level rise and storms, as well as the role of coastal habitats and restored tidal wetlands in providing protection from future inundation. Details of the data analysis process are provided at length in the appendices.  

The report projects that global sea level will rise 8 to 23 centimeters by 2030, relative to the 2000 level, 18 to 48 centimeters by 2050, and 50 to 140 centimeters by 2100.  The 2100 estimate is substantially higher than the IPCC's projection made in 2007 of 18 to 59 centimeters with a possible additional 17 centimeters if rapid changes in ice flow are included. The projections show a sharp distinction at Cape Mendocino in northern California. South of that point, sea-level rise is expected to be very close to global projections; north of that point, sea-level rise is projected to be less than global projections because seismic strain is pushing the land upward.

The study was sponsored by the states of California, Washington, and Oregon; National Oceanic and Atmospheric Administration; U.S. Geological Survey; and U.S. Army Corps of Engineers.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. 

Publication Date: June 2012

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