Consensus Report

The Potential Impacts of Climate Change on U.S. Transportation (2008)

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This report explores the consequences of climate change for U.S. transportation infrastructure and operations. The report provides an overview of the scientific consensus on the current and future climate changes of particular relevance to U.S. transportation, including the limits of present scientific understanding as to their precise timing, magnitude, and geographic location; identifies potential impacts on U.S. transportation and adaptation options; and offers recommendations for both research and actions that can be taken to prepare for climate change. The report also summarizes previous work on strategies for reducing transportation-related emissions of carbon dioxide -- the primary greenhouse gas -- that contribute to climate change.

Key Messages

  • Better decision support tools are also needed to assist transportation decision makers.
  • Climate change will affect transportation primarily through increases in several types of weather and climate extremes, such as very hot days; intense precipitation events; intense hurricanes; drought; and rising sea levels, coupled with storm surges and land subsidence. The impacts will vary by mode of transportation and region of the country, but they will be widespread and costly in both human and economic terms and will require significant changes in the planning, design, construction, operation, and maintenance of transportation systems.
  • Current institutional arrangements for transportation planning and operations were not organized to address climate change and may not be adequate for the purpose.
  • Federal agencies have not focused generally on adaptation in addressing climate change.
  • Greater use of technology would enable infrastructure providers to monitor climate changes and receive advance warning of potential failures due to water levels and currents, wave action, winds, and temperatures exceeding what the infrastructure was designed to withstand.
  • Locally controlled land use planning, which is typical throughout the country, has too limited a perspective to account for the broadly shared risks of climate change.
  • Projected increases in extreme weather and climate underscore the importance of emergency response plans in vulnerable locations and require that transportation providers work more closely with weather forecasters and emergency planners and assume a greater role in evacuation planning and emergency response.
  • Public authorities and officials at various governmental levels and executives of private companies are continually making short- and long-term investment decisions that have implications for how the transportation system will respond to climate change in the near and long terms.
  • Reevaluating, developing, and regularly updating design standards for transportation infrastructure to address the impacts of climate change will require a broad-based research and testing program and a substantial implementation effort.
  • The National Flood Insurance Program and the FIRMs used to determine program eligibility do not take climate change into account.
  • The geographic extent of the United States from Alaska to Florida and from Maine to Hawaii and its diversity of weather and climate conditions can provide a laboratory for identifying best practices and sharing information as the climate changes.
  • The greatest impact of climate change for North America's transportation systems will be flooding of coastal roads, railways, transit systems, and runways because of global rising sea levels, coupled with storm surges and exacerbated in some locations by land subsidence.
  • The significant costs of redesigning and retrofitting transportation infrastructure to adapt to potential impacts of climate change suggest the need for more strategic, risk-based approaches to investment decisions.
  • Transportation planners are not currently required to consider climate change impacts and their effects on infrastructure investments, particularly in vulnerable locations.
  • Transportation professionals often lack sufficiently detailed information about expected climate changes and their timing to take appropriate action.
  • (in terms of magnitude and frequency) of weather and climate extremes, such as record rainfall and record heat waves, not experienced in modern times as human-induced changes are superimposed on the climate's natural variability.