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CRD's Michael Wehner Contributes to National Report on Impacts of Climate Change on Transportation

March 12, 2008

WASHINGTON, D.C. – According to a report issued this week by the National Research Council, every mode of transportation in the U.S. will be affected as the climate changes, with the greatest impact expected to result from flooding of roads, railways, transit systems, and airport runways in coastal areas because of rising sea levels and surges brought on by more intense storms. Though the impacts of climate change will vary by region, it is certain they will be widespread and costly in human and economic terms, and will require significant changes in the planning, design, construction, operation, and maintenance of transportation systems.

The report, “The Potential Impacts of Climate Change on U.S. Transportation,” draws upon five papers commissioned by the Transportation Research Board, which like the National Research Council, is part of the National Academies. Michael Wehner, a climate modeling researcher in Berkeley Lab’s Computational Research Division, is a co-author of one of the papers used to produce the report.

The paper, “Climate Variability and Change with Implications for Transportation,” was co-authored by Thomas C. Peterson, Marjorie McGuirk and Tamara G. Houston of the National Oceanographic and Atmospheric Administration’s (NOAA) National Climatic Data Center and Andrew H. Horvitz of NOAA’s National Weather Service, and Wehner.

According to their paper, in coastal California, where El Niño associated sea-level rise is roughly 12 inches, maximum sea-level variation due to tides or storm surge (2 to 10 feet) is large compared to anticipated climate-change local sea-level rise (8 inches). California airports in San Francisco, Santa Barbara, and Oakland, with field elevations 11, 10 and 6 feet respectively, could be inundated under conditions of extreme high tides coupled with flood conditions and exacerbated by local sea-level rise. In the Bay Area, major highways and railroads near sea level could also be threatened by rises in sea level.

The U.S. transportation system was designed and built for local weather and climate conditions, predicated on historical temperature and precipitation data.  The report finds that climate predictions used by transportation planners and engineers may no longer be reliable, however, in the face of new weather and climate extremes.  Infrastructure pushed beyond the range for which it was designed can become stressed and fail, as seen with loss of the U.S. 90 Bridge in New Orleans after Hurricane Katrina.

To generate their climate projections, Wehner and his co-authors first analyzed 55 years of climate data (daily maximum and minimum temperature and precipitation) from 1950 to 2005. To project the future, they used the World Climate Research Programme’s CMIP3 database of climate model simulations of realistic scenarios of future greenhouse gas emissions. The models used as the basis of the report were integrated for the Intergovernmental Panel on Climate Change’s Fourth Assessment Report, a comprehensive international document which was released last year and awarded the 2007 Nobel Peace Prize.

The simulation data, from over 25 climate models, was collected and archived by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) at the Lawrence Livermore National Laboratory. Climate researchers in the U.S., Norway, Canada, France, Australia, Russia, Germany, Korea, China, Japan and the United Kingdom contributed model output used in the report. From this data, three specific scenarios of the future were analyzed for their predicted impacts on the U.S. transportation sector.

For more information:
Visit the Transportation Research Board’s announcement at, with links to the report and a news release.

Read the Climate Variability and Change with Implications for Transportation paper at

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