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Flash Forward 100 Years: Climate Change Scenarios in California's Bay-Delta

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U.S. Geological Survey (USGS) scientists and academic colleagues investigated how California’s interconnected San Francisco Bay and Sacramento-San Joaquin Delta (the Bay-Delta system) is expected to change from 2010 to 2099 in response to both fast and moderate climate-warming scenarios. Their results, published September 2011 in the journal PLoS ONE (, indicate that this area will be affected by global climate change in the 21st century, with shifts in its biological communities, rising sea level, and modified water supplies.

“The protection of California’s Bay-Delta system will continue to be a top priority for maintaining the state’s agricultural economy, water security for tens of millions of users, and habitat essential to a valuable ecosystem,” said USGS Director Marcia McNutt. “This new USGS research complements ongoing initiatives to conserve the Bay-Delta by providing sound scientific understanding for managing this valuable system such that it continues to provide the services we need in the face of climate uncertainty.”

study area
Above: Landsat Thematic Mapper (TM) satellite imagery of study area (red rectangle in index map) draped over digital elevation models. Modified from [larger version]

This study provides the first integrated assessment of how the Bay-Delta system will respond to climate change. Results show that the combined effects of increasing water temperature and salinity could reduce habitat quality for native species, such as the endangered Delta smelt and winter-run Chinook salmon, and intensify the challenge of sustaining their populations. The study indicates that water-resource planners will need to develop adaptation strategies to address potentially longer dry seasons, diminishing snowpacks, and earlier snowmelt leaving less water for runoff in the summer. The study also describes risk from flooding as sea-level rise accelerates and extreme water levels become increasingly common. Increased intensity and frequency of winter flooding could also occur as results of earlier snowmelt and a shift from snow to rain.

A small slough in Suisun Bay, California.
Above: A small slough in Suisun Bay, California. Photograph by Francis Parchaso, USGS. [larger version]

The Delta provides drinking water to 25 million people and irrigation water to farmland producing crops valued at $36 billion per year. Intensive efforts are underway among the USGS, the Bureau of Reclamation, the Fish and Wildlife Service, the National Oceanic and Atmospheric Administration (NOAA), and the state of California to address what will be increasingly difficult decisions regarding allocations of water for human consumption and biological needs. The report’s findings provide new information that can inform planning of next steps in collaborative initiatives, such as the Bay Delta Conservation Plan, and contribute to the scientific foundation underlying the Delta Stewardship Council’s Delta Plan.

“As we plan for the future, it is important to consider more than just global warming,” said USGS scientist and the study’s lead author James Cloern. “We also have to consider other drivers, such as land-use changes and population growth. A comprehensive assessment of the future looks at responses to global warming in the context of all factors that will change the resources we value.”

In addition to providing future visions of the Bay-Delta system, this research provides general lessons to guide development of adaptation strategies for coping with climate change in other coastal landscapes. Anticipation, flexibility, and adaptability will be the keys to the success of those strategies.

The article about this study, titled “Projected Evolution of California’s San Francisco Bay-Delta-River System in a Century of Climate Change,” is posted at


Related Web Sites
Projected Evolution of California's San Francisco Bay-Delta-River System in a Century of Climate Change
Bay Delta Conservation Plan
collaborative initiative
Delta Plan
Delta Stewardship Council

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Arctic Expedition Reaches 88.5 Degrees North Latitude

Collaborative Seafloor-Mapping Program Completes Final Surveys

Seafloor-Sampling Survey off Massachusetts

Coral Reef Disease Hits Kāne'ohe Bay, Hawai'i

Climate Change Scenarios in California's Bay-Delta

"Hurricane" Movie and TV Series to Feature USGS Scientists

Public Forum On Seafloor Mapping at the Ocean Explorium

Working Sessions on Use Cases for Semantic-Web Development

Workshop on Fledermaus Software

Video Podcast Series Wins 2011 USGS Shoemaker Award

Staff Sedimentologist Arnold H. Bouma Passes Away

Publications Views of South San Francisco Bay Before Salt-Pond Restoration

Using Mangrove Peat to Study Ancient Coastal Environments and Sea-Level Rise

Jan. / Feb. 2012 Publications

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