Tuesday, July 31, 2012
More Hot Julys, Rises in Sea Level Three Feet or More Forecast in State Report
Scripps Oceanography researchers contribute to latest report on climate vulnerability and adaptation
Scripps Institution of Oceanography / University of California, San DiegoAt the end of a July that broke heat records across the country, a new report released today by two state agencies projects that summer months of extreme heat will be the norm by 2060.
The assessment of rising July temperatures was one of several studies supporting and contributing to the report made by researchers at Scripps Institution of Oceanography at UC San Diego. Another analysis by Scripps researchers contains scenarios that sea level along the California coast would reach three to four feet higher than it was in 2000. A third Scripps study concluded that if the most extreme global sea level estimates are realized, "at the end of the twenty-first century coastal managers can anticipate that coastal flooding events of much greater magnitude than those during the 1982-83 El Niño will occur annually."
The report, titled "Our Changing Climate 2012, Vulnerability and Adaptation to the Increasing Risks from Climate Change in California," is the third in an ongoing series of assessments commissioned by the California Energy Commission and the California Natural Resources Agency to help it plan for the state's climate future. Researchers affiliated with Scripps led four of the studies included in the report.
"Significant increases in wildfires, floods, severe storms, drought and heat waves are clear evidence that climate change is happening now. California is stepping up to lead the way in preparing for - and adapting to - this change," said Secretary for Natural Resources John Laird. "These reports use cutting-edge science to provide an analytical roadmap, pointing the way for taking concrete steps to protect our natural resources and all Californians."
Scripps climate researcher David Pierce led a study supporting the new report, estimating climate changes anticipated in the 2060s. Pierce said it is one of the most comprehensive simulations to date using statistical and dynamical downscaling, a method of computer modeling that extrapolates climate phenomena from coarse-resolution global models to California's rugged landscape. He added that while his team's projections show a surprising number of Januaries 50 years from now that are comparably cold to today's Januaries, summers get much hotter.
Computer model estimates of temperature change (°C) from years 1985-94 to 2060-2069
"What today would be considered an exceptional, record-breaking July will by 2060 be considered to be moderately cool," he said.
Dan Cayan, a climate researcher with dual appointments at Scripps and the U.S. Geological Survey, led two reports. One dealt with climate change implications for the San Francisco Bay area and the other with sea-level rise projections.
In the sea-level rise analysis, Cayan and colleagues report that their computer models suggest an increasing tendency for heightened sea level events. The number of hours per year in which sea levels exceed high historical thresholds is expected to increase. By 2100, a mid-range scenario of sea level rise for the central and southern California coast is three feet higher than present-day sea level, and by mid-21st Century the number of exceedances over historical extremes of only one hour per year will likely climb to 75 hours per year. The most extreme sea level episodes during the next several decades will follow historical patterns wherein large storms coincide with high tides, often during El Niño years, but will be amplified as mean sea level rises.
Sea-level rise projections for San Francisco
"Sea-level rise is a challenge to California because of vulnerable real estate and infrastructure along its long open coast as well as in the San Francisco Bay/Delta estuary," Cayan said.
Scripps oceanographer Peter Bromirski led a team that analyzed future risks of coastal flooding. The researchers determined that relative sea level off the West Coast, which is distinct from global sea level, is the key factor influencing increased flooding potential. Other variables such as the strength of storms or the frequency of large wave events are not expected to increase significantly in this century, they added.
Bromirski had reported in a previous study that the West Coast has not experienced the sea-level rise that most other areas of the world have over the past 30 years because of prevailing climate conditions.
"Critical infrastructure, such as roads, railroads, and power generation and transmission systems, are located in coastal zones that will be impacted by flooding and coastal erosion. This study demonstrates that increases in the frequency and severity of coastal flooding events are directly linked to the magnitude of sea level rise," said Bromirski.
Konstantine Georgakakos, an adjunct professor at Scripps and director of the Hydrological Research Center in San Diego, and colleagues reviewed water resources management, primarily the operation of Northern California dams, in the context of climate change. The team concluded that current management policy, which relies heavily on long-term historical norms, will likely be insufficient to cope with the increasing variability brought about by climate change, but forecast-informed management would offer better results. The authors - from the Hydrological Resource Center, the Georgia Water Resources Institute at Georgia Tech, Scripps Oceanography and Taiwan's National Central University - found that adaptive management, which relies more on improved forecasting methods and greater inclusion of uncertainty information, stands a better chance of avoiding crises in water delivery in coming decades.
"The effects that climate change and water demand increase are projected to have on reservoir water management in California makes timely the effort to adjust policy and institutional frameworks now to allow water managers to make adaptive water release and allocation decisions based on the use of quantitative science-based forecasts," said Georgakakos.
Other studies included in the California Energy Commission report addressed several key sectors ranging from the potential influence of climate change on freshwater fishes to its effects on agriculture and electricity demand.
This assessment follows up on discussions and topics presented at the Governor's Conference on Extreme Climate Risks and California's Future, held last December in San Francisco and at an accompanying science meeting
hosted by Scripps Oceanography prior to the conference. The new studies will provide a foundation for the 2012 Climate Adaptation Strategy, with completion expected in December 2012.
"The Governor is committed to rigorous climate science and understanding the impacts of climate change on California so that we can respond, adapt, and continue to prosper," said Ken Alex, Senior Policy Advisor to Governor Edmund G. "Jerry" Brown, and Director of the Office of Planning and Research. "Wise investment in our State's future depends on the science, and is key to strengthening California's economy and protecting the health of our citizens."
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