Global warming threatens Delta smelt, salmon, says report
November 3, 2011
• USGS prognosticates on potential impact on Sacramento-San Joaquin Delta
• ‘As we plan for the future, it is important to consider more than just global warming’
The combined impact on the Sacramento-San Joaquin Delta of increasing water temperature and salinity brought on by global warming 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, says a new study by the U.S. Geological Survey.
The study indicates that water-resource planners will need to develop adaptation strategies to address potentially longer dry seasons, diminishing snow packs and earlier snowmelt leaving less water for runoff in the summer.
It also describes risks 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 a result of earlier snowmelt and a shift from snow to rain, it says.
The USGS says its study provides the first integrated assessment of how the Bay-Delta system will respond to climate change from 2010 to 2099 in response to both fast and moderate climate warming scenarios.
Results indicate that this area will feel impacts of global climate change in the next 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 to tens of millions of users, and essential habitat to a valuable ecosystem," says 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."
The Delta provides drinking water to 25 million people and irrigation water to farmland producing crops valued at $36 billion per year.
Efforts are underway among the USGS, the Bureau of Reclamation, the Fish and Wildlife Service, NOAA, and the state of California to address what the USGS says will be increasingly difficult decisions regarding allocations of water for human consumption and biological needs.
The USGS says 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 science 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," says 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."