Displaced segments on I-10 – U.S. 90 ramp in Mobile Bay.
Washington— Every mode of transportation in the United States will be affected by climate change, and planning to keep things running must begin now, says a new report to the government. The greatest potential impact will be flooding of roads, railways, transit systems, and airport runways in coastal areas, due to rising sea levels and surges brought on by more intense storms. Transport on rivers and roads in the nation’s center also are at risk, says the report, issued this week by the National Research Council. A committee of authors warns that climate shifts will require significant changes in design, construction, operation and maintenance of transportation systems.
Transportation systems have been designed and built based on historical temperature and precipitation data, but the panel points out that this data may no longer be reliable 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.
"Katrina was a preview of what is coming in many other places," said coauthor Klaus Jacob, an expert in coastal hazards at Lamont-Doherty Earth Observatory, part of Columbia University’s Earth Institute. "Transportation infrastructure is our Achilles’ heel. If that goes, we can’t walk." Jacob pointed out that much infrastructure in New York City alone, including the subways, airport runways, and vehicle and rail tunnels, are already near, or below, sea level. Nationwide, some 60,000 miles of coastal highways are already subject to periodic flooding, said Henry G. Schwartz, chairman of the panel.
"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 planning," said Schwartz, past president of the consulting firm Svedrup/Jacobs Civil Inc. "It is now possible to project climate changes for large regions such as the eastern United States, on a scale suited for considering regional infrastructure."
The committee identified five changes important to transport:
In addition to climate change, other factors will likely make coastal systems more vulnerable. For one, population is projected to grow in coastal areas; this will boost demand for infrastructure and increase the number of people and businesses potentially in harm's way. Also, continued erosion and loss of wetlands are removing crucial buffer zones that once protected infrastructure.
"Rising temperatures may trigger weather extremes and surprises, such as more rapid melting of the Arctic sea ice than projected," Schwartz added. "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."
Vulnerabilities will extend far beyond coastal areas, said the panel. In the Midwest, increased intense precipitation could augment the severity of flooding, as 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 systems. Lower water levels would reduce vessel shipping capacity, seriously impairing freight movements in the region; this occurred during the drought of 1988, which stranded barge traffic on the Mississippi River. In California, heat waves may increase wildfires that can destroy transportation infrastructure.
Not all changes will be negative. For instance, marine transportation could benefit from more open seas in the Arctic, which could create new and shorter shipping routes and reduce transport time and costs, said the report. In cold regions, rising temperatures could reduce the costs of snow and ice control and make travel conditions safer for passenger vehicles and freight.
Preparing for projected climate changes will be costly, says the report. Needed measures range from retrofitting infrastructure to making major additions, to constructing entirely new infrastructure. The committee noted a need for trading off “the costs of making the infrastructure more robust against the economic costs of failure." Some areas may need drastic measures. With rising sea level, roads, rail lines and airport runways in low-lying coastal areas may have to protected with expensive sea walls or levees; some facilities may require total relocation.
The report calls for the federal government to take a strong role in implementing some recommendations. These include creation of a clearinghouse for information on transportation and climate change; establishment of a research program to re-evaluate existing design standards; and updating flood insurance maps with climate change in mind.
Many recommendations need not wait for federal action, said the committee. In an interview, Jacob called for entities like the Port Authority of New York/New Jersey to start thinking now about how to keep water out of traffic and rail tunnels using gates, berms or other structures. “This kind of planning is already long overdue,” he said. “It is going to cost many billions of dollars, but it has to be done.”
The report was a collaboration between the Transportation Research Board and the Division on Earth and Life Studies of the National Research Council. Copies of the report, “Potential Impacts of Climate Change on US Transportation,” are available at www.trb.org.