Berkeley Lab Climate Researcher Contributes to Two National Reports on Impacts of Climate Change on Transportation

WASHINGTON — According to a report issued this week by the National Research Council, climate change will affect every mode of transportation in the U.S. The greatest impact is 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 results were published in one of the two reports that contained research by Michael Wehner, climate modeling researcher in Berkeley Lab’s Computational Research Division.

The first 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.l Wehner co-authored one of the papers used to produce the report.

Climate model future projections of surface air temperature (in degrees Centigrade) and their associated uncertainties for a business-as-usual future scenario with little reduction of human-produced greenhouse gas emissions.

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, Andrew H. Horvitz of NOAA’s National Weather Service, and Wehner.

The second report, “Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study, Phase I,” provides an assessment of the vulnerabilities of transportation systems in the region to potential changes in weather patterns and related impacts, as well as the effect of natural land subsidence and other environmental factors in the region. The area examined by the study, issued by the U.S. Department of Transportation, includes 48 contiguous counties in four states, running from Galveston, TX to Mobile, AL.

Throughout the country, transportation planners and engineers use historical temperature and precipitation data to help them design transportation systems that can withstand local weather and climate conditions. Both reports find that those climate predictions may no longer be reliable, however, in the face of new weather and climate extremes. Roads, transit systems and airports that were built based on older data could fail as a result.

The first report focuses on the entire U.S. and its territories and finds that California airports in San Francisco, Santa Barbara, and Oakland 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. Not all climate changes will be negative, however. Marine transportation could benefit from more open seas in the Arctic, creating new and shorter shipping routes and reducing transport time and costs. In cold regions, rising temperatures could reduce the costs of snow and ice control and would make travel conditions safer for passenger vehicles and freight.

The second report focuses solely on the U.S. Central Gulf Coast and finds that changes in climate could disrupt transportation services in the region. Twenty-seven percent of major roads, 9 percent of rail lines, and 72 percent of area ports could be vulnerable to flooding due to future sea level rise.

For both reports, Wehner and his co-authors first analyzed observed climate data (daily temperature and precipitation) from 1950 to 2005. Then they used the large collection of climate model data, archived at the Program for Climate Model Diagnosis and Intercomparison (PCMDI) at Lawrence Livermore National Laboratory, to validate the models against observations and to create plausible projections of future climate change relevant to transportation analysts. They considered future scenarios ranging from very aggressive reduction of human-produced greenhouse gas emissions to none at all.

The simulation data, based on 25 climate models, reflect the climate research community’s collective efforts to predict the global climate of the future. The simulations took into account different factors based on economical, technological, and sociological conditions and assumptions. Researchers from the U.S., Norway, Canada, France, Australia, Russia, Germany, Korea, China, Japan and the United Kingdom contributed to the collection at PCMDI. The Intergovernmental Panel on Climate Change (IPCC) used these data for its Fourth Assessment Report released last year, a comprehensive document that won the IPCC a share of the 2007 Nobel Peace Prize.