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Rising seasLatest science on sea level rise projections: In support of California policy guidance

Published 18 April 2017

An estimated 75 percent of California’s population lives in coastal counties. Sea-level rise, already underway, threatens hundreds of miles of roads and railways, harbors, airports, power plants, wastewater treatment plants, coastal wetlands, beaches, dunes, bluffs, and thousands of businesses and homes. In a comprehensive analysis of the factors that affect how much the ocean will rise along California’s coast in coming decades, a seven-member team of experts has provided the state with a report on the best-available sea-level rise science — including recent scientific advances on the role of polar ice loss.

In a comprehensive analysis of the factors that affect how much the ocean will rise along California’s coast in coming decades, a seven-member team of experts has provided the state with a report on the best-available sea-level rise science — including recent scientific advances on the role of polar ice loss.

The report includes new information on the expected sea level changes that will occur based on different greenhouse gas emission scenarios. For example, with very successful mitigation efforts, the report states that there is a 67 percent probability that the Bay Area will experience sea level rise between 1.0 foot and 2.4 feet by 2100. However, if no significant mitigation efforts are taken, that range increases to 1.6 to 3.4 feet.

CNRA says that the report also emphasizes the importance of preparing for extreme but uncertain scenarios involving the rapid loss of the Antarctic ice sheet, which would have an enormous impact on coastal regions. In one such scenario, sea levels along California’s coastline could rise up to 10 feet by 2100 – about 30-40 times faster than sea-level rise experienced over the last century. 

“Although our scientific understanding is rapidly increasing, waiting for scientific certainty about the rate or ultimate amount of sea-level rise is neither a safe nor prudent option” said Dr. Gary Griggs, Chair of the science team and professor at University of California Santa Cruz. “The sea-level rise projections presented in this report provide the scientific foundation for taking action today, preparing our coastal communities and mitigating hazards, and preventing much greater losses than will occur without action now.”

An estimated 75 percent of California’s population lives in coastal counties. Sea-level rise, already underway, threatens hundreds of miles of roads and railways, harbors, airports, power plants, wastewater treatment plants, coastal wetlands, beaches, dunes, bluffs, and thousands of businesses and homes.

The new science report was requested by the California Ocean Protection Council and the California Natural Resources Agency, in collaboration with the Governor’s Office of Planning and Research, the California Energy Commission, and the California Ocean Science

Trust.  Expertise on the scientific team includes risk assessment, climatic change, ice sheet behavior, and statistical modeling.

The science report will be presented on April 26 at a meeting in Sacramento of the OceanProtection Council. The report provides the scientific basis for updating statewide policy, which guides state and local decisions along California shorelines.