The impacts from sea level rise and storm surge, extreme weather events, higher temperatures and heat waves, precipitation changes, Arctic warming, and other climatic conditions are affecting the reliability and capacity of the U.S. transportation system in many ways.

This finding is from chapter 5 of Climate Change Impacts in the United States: The Third National Climate Assessment.

Process for developing key messages: In developing key messages, the chapter author team engaged, via teleconference, in multiple technical discussions from January through May 2012 as they reviewed numerous peer reviewed publications. Technical input reports (21) on a wide range of topics were also received and reviewed as part of the Federal Register Notice solicitation for public input. The author team’s review included a foundational Technical Input Report for the National Climate Assessment, “Climate Impacts and U.S. Transportation.”6b4d3283-49dc-4b8d-830b-aa554e37279f Other published literature and professional judgment were also considered as the chapter key messages were developed. The chapter author team met in St. Louis, MO, in April 2012 for expert deliberation and finalization of key messages.

Description of evidence base: Climate impacts in the form of sea level rise, changing frequency of extreme weather events, heat waves, precipitation changes, Arctic warming, and other climatic conditions are documented in Ch. 2: Our Changing Climate of this report. Climate can be described as the frequency distribution of weather over time. Existing weather conditions, flooding, and storm surge demonstrably affect U.S. transportation systems. By changing the frequency of these weather conditions, climate change will inevitably affect the reliability and capacity of U.S. transportations systems. This view is supported by multiple studies of the impacts of weather and climate change on particular transportation systems or particular regions. An aggregate summary of impacts of climate change on U.S. transportation can be found in NRC 2008.351fbf4f-480e-450e-9cc3-9cecd429f564 A paper commissioned for NRC 2008 considers specific impacts of various forms of climate change on infrastructure, for example, possible future constraints on infrastructure.8aa9da42-0886-4d5a-8206-758e5e422fb0 The effects of climate on transit systems are summarized in Hodges 2011.c41596dd-67b3-460a-8e7c-5b9e5c2a986a The impact of heat and other climate effects on rail systems are described by Hodges 2011 and Rossetti 2002.c41596dd-67b3-460a-8e7c-5b9e5c2a986a 91adc650-70a1-4503-bbdb-ddf5a7c54e36 Future impacts of sea level rise and other climatic effects on transportation systems in the Gulf Coast were examined by CCSP 2008.8dbd70c4-cd8c-4dce-b27c-bfb412901e58 The impacts of climate change on New York State, including its transportation system, were undertaken by Rosenzweig et al. 2011.78fbf40c-2639-480a-8410-5be748750f2b Impacts of sea level rise on transportation infrastructure for the mid-Atlantic were also discussed in CCSP 2009 SAP 4.1, Ch. 7.1bc74f07-688c-482c-a923-483f5d3de8b5 Weather impacts on road systems are discussed in “Climate Impacts and U.S. Transportation”6b4d3283-49dc-4b8d-830b-aa554e37279f and numerous other sources. Weather impacts on aviation operations are discussed in Kulesa 2003e45eaccb-5458-4b53-8b7d-83965b25c618 and numerous other sources. In addition, the key message and supporting text summarize extensive evidence documented in “Climate Impacts and U.S. Transportation.”6b4d3283-49dc-4b8d-830b-aa554e37279f Additional peer-reviewed publications discuss the fact that Arctic warming is affecting existing Alaskan transportation infrastructure today, and is projected to allow the seasonal opening of the Northwest Passage to freight shipment.be475fb9-807d-4a7b-8ae7-418ef91e5a20

New information and remaining uncertainties: Recent changes in global sea level rise estimates documented in this report (Ch.2: Our Changing Climate, Key Message 10) have not been incorporated into existing regional studies of coastal areas. In addition, recent research by USGS on the interaction between sea level rise, wave action, and local geology have been incorporated in only a few studies.5ddaab38-f315-487d-8b7a-bb322bb9b60c Specific estimates of climate change impacts on transportation are acutely sensitive to regional projections of climate change and, in particular, to the scale, timing, and type of predicted precipitation. New (CMIP5-based) regional climate projections will therefore affect most existing specific estimates of climate change impacts on transportation. Transportation planning in the face of uncertainties about regional-scale climate impacts presents particular challenges. Impacts of climate on transportation system operations, including safety and congestion, both on road systems and in aviation, have been little studied to date. Future characteristics of society, such as land-use patterns, demographics, and the use of information technology to alter transportation patterns, and possible changes to the very nature of future transportation systems themselves all create uncertainty in evaluating climate impacts on the nation’s transportation networks. These societal changes will probably occur gradually, however, allowing the transportation systems to adapt. Adaptation can significantly ameliorate impacts on the transportation sector; however, evaluation of adaptation costs and strategies for the transportation sector is at a relatively early stage.

Assessment of confidence based on evidence: Confidence is high that transportation systems will be affected by climate change, given current climate projections, particularly regarding sea level rise and extreme weather events.

References :

• The Potential Impacts of Climate Change on Transportation, Summary and Discussion Papers, Federal Research Partnership Workshop, October 1-2, 2002 (e45eaccb)
• Coastal Sensitivity to Sea Level Rise: A Focus on the Mid-Atlantic Region. A report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research (1bc74f07)
• Developing coastal adaptation to climate change in the New York City infrastructure-shed: process, approach, tools, and strategies (78fbf40c)
• The Potential Impacts of Climate Change on Transportation, Summary and Discussion Papers, Federal Research Partnership Workshop, October 1-2, 2002 (91adc650)
• Climate Impacts and U.S. Transportation: Technical Input Report for the National Climate Assessment. DOT OST/P-33 (6b4d3283)
• Flooded Bus Barns and Buckled Rails: Public Transportation and Climate Change Adaptation. FTA Report No. 0001 (c41596dd)
• Arctic Marine Shipping Assessment Report 2009 (be475fb9)
• Design Standards for US Transportation Infrastructure: The Implications of Climate Change (8aa9da42)
• Potential Impacts of Climate Change on U.S. Transportation. Special Report 290 (351fbf4f)
• SAP 4.7. Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study (8dbd70c4)
• A Bayesian network to predict coastal vulnerability to sea level rise (5ddaab38)