Every mode of transportation in the United States will be affected as the climate warms, with the greatest impact expected to be 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, says a new report from the National Research Council.

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.

"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 firm Sverdrup/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.

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.