Research Highlight: State Report Says Summers to be Hotter, Seas to be Higher this Century

July 2012 was the hottest month in the continental United States on record, but scenarios investigated by Scripps Institution of Oceanography, UC San Diego researchers indicate that such extremely hot Julys could be the norm in California by 2060.

The assessment of rising temperatures was one of several studies contributing to a report released July 31 by the California Energy Commission and the California Natural Resources Agency. Another analysis by Scripps researchers contains scenarios in which sea level along the California coast reaches three to four feet higher than it was in 2000.   A third Scripps study concluded that if sea level rises to this degree, “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.”

Contributors to “Our Changing Climate 2012, Vulnerability and Adaptation to the Increasing Risks from Climate Change in California,” and the report’s users said that the ongoing research into California’s climate future is an investment that could protect billions of dollars in averted damage if extreme weather events become more common.

A roughly $60 million annual budget raised from fees collected in utility bills has supported research and development of new energy technologies. Energy studies administered by the CEC’s Public Interest Energy Research (PIER) program has already been credited for the creation of energy efficiency standards in buildings and appliances that save energy users in California as much as $1 billion per year.

“We know that climate change will significantly affect the state’s energy supply and demand,” said Energy Commission Chair Robert B. Weisenmiller. “This groundbreaking research gives us the data and analytical tools we need to better plan, forecast and prepare to meet the state’s energy needs as we face climate challenges.”

About $1.5 million of PIER’s annual budget for R&D funded studies on climate impacts and adaptation measures to the energy sector and other related sectors. Current PIER-supported research is helping municipalities and resource managers create strategies to deal with scenarios ranging from coastal flooding that makes residential areas inaccessible to first responders to increased nighttime heat wave episodes prodding high energy demand 24 hours a day in summer. Other PIER studies are helping California’s $30-billion-a-year agricultural sector adapt to climate-related stresses.

“California has, more than other regions in the United States, undertaken a comprehensive, repeated evaluation of climate change impacts and adaptation options,” Dan Cayan, a climate researcher with dual appointments at Scripps and the U.S. Geological Survey.  “The need for regional assessment here is underscored by the State’s semi-arid climate and the proclivity for large variations, its remarkable physical structure, overlain by our diverse human environment.”

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 winters 50 years from now that are comparably cold to today’s winters, summers get much hotter.

“What today would be considered an exceptional, record-breaking July will by 2060 be considered to be moderately cool,” he said.

Cayan 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. Sea level rise scenarios vary quite widely, but most project upward trends in global and regional sea level along the California coast that are considerably faster than the 1.8-centimeter (0.7-inch)-per-decade rate observed over much of the last century.

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.  Thus, the number of hours per year in which sea levels exceed high historical thresholds is expected to increase. Under this mid-range scenario, storm-forced high-sea-level events that, on average, occur only one hour per year now would be far more common, occurring over 50 hours per year toward the end of the century.

The most extreme sea level episodes during the next several decades will follow historical patterns in which the highest storm-forced sea level extremes will occur during high tides, often during El Niño years, but these extreme sea levels will be amplified as mean sea level rises.

“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. Because the strength of storms or the frequency of large wave events are not projected to increase over the 21^st century, the researchers determined that relative sea level along the West Coast, which is distinct from global mean sea level, is a more important factor influencing increased flooding potential.

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 shorter period climate patterns, but these could possibly shift in the next decade or so.

“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 the magnitude of regional sea-level rise will determine how much the frequency and severity of coastal flooding events increase” said Bromirski.

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.

– Robert Monroe

Related Image Gallery: State Report Says Summers to be Hotter, Seas to be Higher this Century