U.S. Transport Systems Vulnerable to Climate Change

The report identifies five climate changes of particular importance to U.S. transportation - increases in very hot days and heat waves; increases in Arctic temperatures; rising sea levels; increases in intense precipitation events; and increases in hurricane intensity.

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 major changes in the planning, design, construction, operation, and maintenance of transportation systems, the committee concludes.

Evacuation of New Orleans flooded by Hurricane Katrina. September 1, 2005 (Photo by Michael Rieger courtesy FEMA)

"The time has come for transportation professionals to acknowledge and confront the challenges posed by climate change, and to incorporate the most current scientific knowledge into the planning of transportation systems," said Henry Schwartz Jr., past president and chairman of the engineering firmSverdrup/Jacobs Civil Inc., and chair of the committee that wrote the report.

"Rising temperatures may trigger weather extremes and surprises, such as more rapid melting of the Arctic sea ice than projected," Schwartz said. "The highways that currently serve as evacuation routes and endure periodic flooding could be compromised with strong hurricanes and more intense precipitation, making some of these routes impassable."

Transportation providers will need to focus on evacuation planning and work more closely with weather forecasters and emergency planners, the said the committe, which includes meteorologists, climate scientists and planners as well as transportation officials from Massachusetts, New York, Texas and California.

"It is now possible to project climate changes for large subcontinental regions, such as the Eastern United States, a scale better suited for considering regional and local transportation infrastructure," Schwartz said.

The U.S. transportation system was designed and built for local weather and climate conditions, predicated on historical temperature and precipitation data, but the report finds that climate predictions used by transportation planners and engineers may no longer be reliable for forecast 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.

U.S. Highway 90 bridge in Biloxi, Mississippi was destroyed by Hurricane Katrina in 2005. (Photo by Mark Wolfe courtesy FEMA)

In addition to climate changes, other vulnerabilities will affect coastal-area transportation systems, the committee notes.

Population is projected to grow in coastal areas, which will boost demand for transportation infrastructure and increase the number of people and businesses potentially in harm's way.

Erosion and loss of wetlands have removed crucial buffer zones that once protected infrastructure, and an estimated 60,000 miles of coastal highways are already exposed to periodic storm flooding.

Infrastructure vulnerabilities will extend inland as the climate continues to change, the committee says.

In the Midwest, increased intense precipitation could augment the severity of flooding, as occurred in 1993 when farmland, towns, and transportation routes were severely damaged from flooding along 500 miles of the Mississippi and Missouri river systems.

On the other hand, drier conditions are likely to prevail in the watersheds supplying the St. Lawrence Seaway and the Great Lakes as well as the Upper Midwest river system.

Lower water levels would reduce vessel shipping capacity, impairing freight movements in the region, such as occurred during the drought of 1988, which stranded barge traffic on the Mississippi River.

And in California, heat waves may increase wildfires that can destroy transportation infrastructure.

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, the report notes. 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.

"Preparing for projected climate changes will be costly," the committee warns.

Response measures range from rehabilitating and retrofitting infrastructure to making major additions to constructing entirely new infrastructure. Roads, rail lines, and airport runways in low-lying coastal areas may become casualties of sea-level rise, requiring relocations or expensive protective measures, such as sea walls and levees.

The report calls for the federal government to perform such services as creation of a clearinghouse for information on transportation and climate change.

Sand pushed inland by the storm surge of Hurricane Jeanne covers a road in Vero Beach, Florida. (Photo by Mark Wolfe courtesy FEMA)

The federal government should establish a research program to re-evaluate existing design standards and develop new standards for addressing climate change, the committee recommends, and should also create an interagency working group on adaptation.

Changes in federal regulations regarding long-range planning guidelines and infrastructure rehabilitation requirements may be necessary.

And the National Flood Insurance Program will need to be re-evaluated and flood insurance rate maps updated with climate change in mind, the committee suggests.

But many recommendations need not wait for federal action, and focusing on the challenges now could help avoid costly transportation investments and disruptions to operations in the future, the committee advises.

Local governments and private infrastructure providers can begin to identify critical infrastructure that is particularly vulnerable to climate change.

Professional organizations can single out examples of best practices, and transportation planners and climate scientists can begin collaboration on the development of regional scenarios for likely climate changes and the data needed to analyze their impacts.

This report is a collaboration between the Transportation Research Board and the Division on Earth and Life Studies of the National Research Council. It was sponsored by six federal government agencies.

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